Vulnerability-Lookup

CVE-2026-80557 (GCVE-0-2026-80557)

Vulnerability from cvelistv5 – Published: 2026-08-26 14:37 – Updated: 2026-08-27 12:40

Title

libceph: fix OOB read in decode_watchers() via missing bounds check

Summary

In the Linux kernel, the following vulnerability has been resolved: libceph: fix OOB read in decode_watchers() via missing bounds check ceph_start_decoding() validates that struct_len bytes remain in the buffer after the encoding header, but accepts struct_len=0 as valid: ceph_decode_need(p, end, 0, bad) always passes. When a malicious or compromised OSD sends an obj_list_watch_response_t reply with struct_len=0, ceph_start_decoding() returns success with p == end, leaving zero bytes guaranteed for subsequent reads. The immediately following ceph_decode_32(p) in decode_watchers() has no preceding bounds check. With p == end this is a 4-byte read past the validated buffer boundary. The garbage value is then passed directly to kzalloc_objs() as the watcher count. The sibling function decode_watcher() already uses the safe variants (ceph_decode_copy_safe, ceph_decode_64_safe, ceph_decode_skip_32) after its own ceph_start_decoding() call. decode_watchers() is the only site that uses the bare variant, confirming an oversight. Fix by replacing ceph_decode_32(p) with ceph_decode_32_safe(p, end, *num_watchers, bad), consistent with the established pattern. Attacker model: a malicious or compromised OSD in a multi-tenant Ceph deployment (e.g. cloud) can trigger this against any kernel client that calls CEPH_OSD_OP_LIST_WATCHERS, without any further privileges beyond OSD session establishment. [ idryomov: trim changelog ]

Severity

9.8 (Critical)


                        
                          CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Assigner

Linux mitre root

References

8 references

URL	Tags
https://git.kernel.org/stable/c/85479b7d65b4ebcb0…
https://git.kernel.org/stable/c/1c824e7c75bb4adf1…
https://git.kernel.org/stable/c/f161be39201eb5f9b…
https://git.kernel.org/stable/c/eab3eeb68bfc639d7…
https://git.kernel.org/stable/c/c59219a6b62d74936…
https://git.kernel.org/stable/c/cb8246e5846dbbe34…
https://git.kernel.org/stable/c/7130d94846dadbb97…
https://git.kernel.org/stable/c/00ead17c7de137a69…

Impacted products

2 products

Vendor	Product	Version	CPE status
Linux	Linux	Affected: a4ed38d7a180f184a6e7aedd09db9ca4b1e6a71c , < 85479b7d65b4ebcb07fbbe57230976793974ab4a (git) Affected: a4ed38d7a180f184a6e7aedd09db9ca4b1e6a71c , < 1c824e7c75bb4adf19553dd4ea944a5d83096be8 (git) Affected: a4ed38d7a180f184a6e7aedd09db9ca4b1e6a71c , < f161be39201eb5f9b1f58fb8f90b8a9cd3931eb6 (git) Affected: a4ed38d7a180f184a6e7aedd09db9ca4b1e6a71c , < eab3eeb68bfc639d74f27256f05546af5c4f787d (git) Affected: a4ed38d7a180f184a6e7aedd09db9ca4b1e6a71c , < c59219a6b62d74936963983e5815524c3de8dd79 (git) Affected: a4ed38d7a180f184a6e7aedd09db9ca4b1e6a71c , < cb8246e5846dbbe34930903a90c7a90dd8e5910b (git) Affected: a4ed38d7a180f184a6e7aedd09db9ca4b1e6a71c , < 7130d94846dadbb97b6b7f4d78a3a7bba6e3daa1 (git) Affected: a4ed38d7a180f184a6e7aedd09db9ca4b1e6a71c , < 00ead17c7de137a692edee59f2772e6af687e8eb (git)	guessed
Linux	Linux	Affected: 4.9 Unaffected: 0 , < 4.9 (semver) Unaffected: 5.10.267 , ≤ 5.10.* (semver) Unaffected: 5.15.218 , ≤ 5.15.* (semver) Unaffected: 6.1.185 , ≤ 6.1.* (semver) Unaffected: 6.6.154 , ≤ 6.6.* (semver) Unaffected: 6.12.106 , ≤ 6.12.* (semver) Unaffected: 6.18.47 , ≤ 6.18.* (semver) Unaffected: 7.1.10 , ≤ 7.1.* (semver) Unaffected: 7.2 , ≤ * (original_commit_for_fix)	guessed

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              "status": "unaffected",
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              "status": "unaffected",
              "version": "6.1.185",
              "versionType": "semver"
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              "version": "6.6.154",
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              "status": "unaffected",
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              "status": "unaffected",
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          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nlibceph: fix OOB read in decode_watchers() via missing bounds check\n\nceph_start_decoding() validates that struct_len bytes remain in the\nbuffer after the encoding header, but accepts struct_len=0 as valid:\nceph_decode_need(p, end, 0, bad) always passes. When a malicious or\ncompromised OSD sends an obj_list_watch_response_t reply with\nstruct_len=0, ceph_start_decoding() returns success with p == end,\nleaving zero bytes guaranteed for subsequent reads.\n\nThe immediately following ceph_decode_32(p) in decode_watchers() has\nno preceding bounds check. With p == end this is a 4-byte read past\nthe validated buffer boundary. The garbage value is then passed\ndirectly to kzalloc_objs() as the watcher count.\n\nThe sibling function decode_watcher() already uses the safe variants\n(ceph_decode_copy_safe, ceph_decode_64_safe, ceph_decode_skip_32)\nafter its own ceph_start_decoding() call. decode_watchers() is the\nonly site that uses the bare variant, confirming an oversight.\n\nFix by replacing ceph_decode_32(p) with ceph_decode_32_safe(p, end,\n*num_watchers, bad), consistent with the established pattern.\n\nAttacker model: a malicious or compromised OSD in a multi-tenant Ceph\ndeployment (e.g. cloud) can trigger this against any kernel client\nthat calls CEPH_OSD_OP_LIST_WATCHERS, without any further privileges\nbeyond OSD session establishment.\n\n[ idryomov: trim changelog ]"
        }
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              "value": "AV:N - The bug is triggered when libceph decodes a crafted MOSDOpReply for CEPH_OSD_OP_LIST_WATCHERS received over the Ceph messenger TCP session from a compromised or malicious OSD; exploitation requires no local syscall, ioctl, or device access on the victim.\nAC:L - A malicious OSD fully controls the reply encoding and can set struct_len=0 with a chosen outdata_len so ceph_start_decoding() leaves p at end and the following ceph_decode_32() deterministically reads attacker-chosen bytes as num_watchers without races or victim-specific memory layout.\nPR:N - The attacker acts as the remote Ceph OSD peer and needs no account, capabilities, or privileges on the victim Linux host; any kernel RBD client connected to a multi-tenant or attacker-controlled cluster is exposed when exclusive-lock recovery issues LIST_WATCHERS.\nUI:N - Once an RBD image with exclusive-lock is mapped, ceph_osdc_list_watchers() is invoked automatically during rbd_try_lock() lock-contention recovery; no additional victim user or administrator action is required at exploit time beyond the existing client session.\nS:U - The out-of-bounds read, attacker-sized heap allocation, and any resulting kernel memory corruption all occur within the victim host kernel Ceph client; the flaw does not cross VM, container, or IOMMU security boundaries.\nC:H - The missing bounds check causes a 4-byte out-of-bounds kernel memory read via ceph_decode_32() when p equals end; per kernel guidance any out-of-bounds read is rated High, and the attacker can place controlled bytes immediately past the validated boundary via outdata_len.\nI:H - The out-of-bounds or attacker-supplied num_watchers value is passed directly to kzalloc_objs(), giving the remote peer control over kernel heap allocation size and subsequent decode_watchers() processing of watcher structures in the RBD exclusive-lock path.\nA:H - The slab out-of-bounds read can trigger KASAN faults or kernel oops on instrumented builds, and a large attacker-chosen num_watchers can cause ENOMEM/OOM or stall the RBD lock worker during repeated decode_watcher() attempts, producing severe repeatable availability loss."
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        {
          "url": "https://git.kernel.org/stable/c/00ead17c7de137a692edee59f2772e6af687e8eb"
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    "cveId": "CVE-2026-80557",
    "datePublished": "2026-08-26T14:37:24.178Z",
    "dateReserved": "2026-08-26T14:34:25.767Z",
    "dateUpdated": "2026-08-27T12:40:16.573Z",
    "state": "PUBLISHED"
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      "date": "2026-08-30",
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With p == end this is a 4-byte read past\\nthe validated buffer boundary. The garbage value is then passed\\ndirectly to kzalloc_objs() as the watcher count.\\n\\nThe sibling function decode_watcher() already uses the safe variants\\n(ceph_decode_copy_safe, ceph_decode_64_safe, ceph_decode_skip_32)\\nafter its own ceph_start_decoding() call. decode_watchers() is the\\nonly site that uses the bare variant, confirming an oversight.\\n\\nFix by replacing ceph_decode_32(p) with ceph_decode_32_safe(p, end,\\n*num_watchers, bad), consistent with the established pattern.\\n\\nAttacker model: a malicious or compromised OSD in a multi-tenant Ceph\\ndeployment (e.g. cloud) can trigger this against any kernel client\\nthat calls CEPH_OSD_OP_LIST_WATCHERS, without any further privileges\\nbeyond OSD session establishment.\\n\\n[ idryomov: trim changelog ]\"}],\"affected\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"affectedData\":[{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"unaffected\",\"programFiles\":[\"net/ceph/osd_client.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"a4ed38d7a180f184a6e7aedd09db9ca4b1e6a71c\",\"lessThan\":\"85479b7d65b4ebcb07fbbe57230976793974ab4a\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"a4ed38d7a180f184a6e7aedd09db9ca4b1e6a71c\",\"lessThan\":\"1c824e7c75bb4adf19553dd4ea944a5d83096be8\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"a4ed38d7a180f184a6e7aedd09db9ca4b1e6a71c\",\"lessThan\":\"f161be39201eb5f9b1f58fb8f90b8a9cd3931eb6\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"a4ed38d7a180f184a6e7aedd09db9ca4b1e6a71c\",\"lessThan\":\"eab3eeb68bfc639d74f27256f05546af5c4f787d\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"a4ed38d7a180f184a6e7aedd09db9ca4b1e6a71c\",\"lessThan\":\"c59219a6b62d74936963983e5815524c3de8dd79\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"a4ed38d7a180f184a6e7aedd09db9ca4b1e6a71c\",\"lessThan\":\"cb8246e5846dbbe34930903a90c7a90dd8e5910b\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"a4ed38d7a180f184a6e7aedd09db9ca4b1e6a71c\",\"lessThan\":\"7130d94846dadbb97b6b7f4d78a3a7bba6e3daa1\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"a4ed38d7a180f184a6e7aedd09db9ca4b1e6a71c\",\"lessThan\":\"00ead17c7de137a692edee59f2772e6af687e8eb\",\"versionType\":\"git\",\"status\":\"affected\"}]},{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"affected\",\"programFiles\":[\"net/ceph/osd_client.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"4.9\",\"status\":\"affected\"},{\"version\":\"0\",\"lessThan\":\"4.9\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"5.10.267\",\"lessThanOrEqual\":\"5.10.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"5.15.218\",\"lessThanOrEqual\":\"5.15.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.1.185\",\"lessThanOrEqual\":\"6.1.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.6.154\",\"lessThanOrEqual\":\"6.6.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.12.106\",\"lessThanOrEqual\":\"6.12.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.18.47\",\"lessThanOrEqual\":\"6.18.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"7.1.10\",\"lessThanOrEqual\":\"7.1.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"7.2\",\"lessThanOrEqual\":\"*\",\"versionType\":\"original_commit_for_fix\",\"status\":\"unaffected\"}]}]}],\"metrics\":{\"cvssMetricV31\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"type\":\"Secondary\",\"cvssData\":{\"version\":\"3.1\",\"vectorString\":\"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H\",\"baseScore\":9.8,\"baseSeverity\":\"CRITICAL\",\"attackVector\":\"NETWORK\",\"attackComplexity\":\"LOW\",\"privilegesRequired\":\"NONE\",\"userInteraction\":\"NONE\",\"scope\":\"UNCHANGED\",\"confidentialityImpact\":\"HIGH\",\"integrityImpact\":\"HIGH\",\"availabilityImpact\":\"HIGH\"},\"exploitabilityScore\":3.9,\"impactScore\":5.9}]},\"references\":[{\"url\":\"https://git.kernel.org/stable/c/00ead17c7de137a692edee59f2772e6af687e8eb\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/1c824e7c75bb4adf19553dd4ea944a5d83096be8\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/7130d94846dadbb97b6b7f4d78a3a7bba6e3daa1\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/85479b7d65b4ebcb07fbbe57230976793974ab4a\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/c59219a6b62d74936963983e5815524c3de8dd79\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/cb8246e5846dbbe34930903a90c7a90dd8e5910b\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/eab3eeb68bfc639d74f27256f05546af5c4f787d\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/f161be39201eb5f9b1f58fb8f90b8a9cd3931eb6\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"}]}}",
    "redhat_vex": {
      "aggregate_severity": "Moderate",
      "current_release_date": "2026-08-27T07:15:31+00:00",
      "cve": "CVE-2026-80557",
      "id": "CVE-2026-80557",
      "initial_release_date": "2026-08-26T00:00:00+00:00",
      "product_status:known_affected": "260",
      "product_status:known_not_affected": "14",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: libceph: fix OOB read in decode_watchers() via missing bounds check",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-80557.json",
      "version": "3"
    }
  }
}

FKIE_CVE-2026-80557

Vulnerability from fkie_nvd - Published: 2026-08-26 15:17 - Updated: 2026-08-27 13:18

Severity

9.8 (Critical) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Summary

References

	URL	Tags
	416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/00ead17c7de137a692edee59f2772e6af687e8eb
	416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/1c824e7c75bb4adf19553dd4ea944a5d83096be8
	416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/7130d94846dadbb97b6b7f4d78a3a7bba6e3daa1
	416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/85479b7d65b4ebcb07fbbe57230976793974ab4a
	416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/c59219a6b62d74936963983e5815524c3de8dd79
	416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/cb8246e5846dbbe34930903a90c7a90dd8e5910b
	416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/eab3eeb68bfc639d74f27256f05546af5c4f787d
	416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/f161be39201eb5f9b1f58fb8f90b8a9cd3931eb6

Impacted products

	Vendor	Product	Version

JSON

To clipboard

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/ceph/osd_client.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "85479b7d65b4ebcb07fbbe57230976793974ab4a",
              "status": "affected",
              "version": "a4ed38d7a180f184a6e7aedd09db9ca4b1e6a71c",
              "versionType": "git"
            },
            {
              "lessThan": "1c824e7c75bb4adf19553dd4ea944a5d83096be8",
              "status": "affected",
              "version": "a4ed38d7a180f184a6e7aedd09db9ca4b1e6a71c",
              "versionType": "git"
            },
            {
              "lessThan": "f161be39201eb5f9b1f58fb8f90b8a9cd3931eb6",
              "status": "affected",
              "version": "a4ed38d7a180f184a6e7aedd09db9ca4b1e6a71c",
              "versionType": "git"
            },
            {
              "lessThan": "eab3eeb68bfc639d74f27256f05546af5c4f787d",
              "status": "affected",
              "version": "a4ed38d7a180f184a6e7aedd09db9ca4b1e6a71c",
              "versionType": "git"
            },
            {
              "lessThan": "c59219a6b62d74936963983e5815524c3de8dd79",
              "status": "affected",
              "version": "a4ed38d7a180f184a6e7aedd09db9ca4b1e6a71c",
              "versionType": "git"
            },
            {
              "lessThan": "cb8246e5846dbbe34930903a90c7a90dd8e5910b",
              "status": "affected",
              "version": "a4ed38d7a180f184a6e7aedd09db9ca4b1e6a71c",
              "versionType": "git"
            },
            {
              "lessThan": "7130d94846dadbb97b6b7f4d78a3a7bba6e3daa1",
              "status": "affected",
              "version": "a4ed38d7a180f184a6e7aedd09db9ca4b1e6a71c",
              "versionType": "git"
            },
            {
              "lessThan": "00ead17c7de137a692edee59f2772e6af687e8eb",
              "status": "affected",
              "version": "a4ed38d7a180f184a6e7aedd09db9ca4b1e6a71c",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "net/ceph/osd_client.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "4.9"
            },
            {
              "lessThan": "4.9",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.10.*",
              "status": "unaffected",
              "version": "5.10.267",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.15.*",
              "status": "unaffected",
              "version": "5.15.218",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.1.*",
              "status": "unaffected",
              "version": "6.1.185",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.154",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.106",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.47",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.1.*",
              "status": "unaffected",
              "version": "7.1.10",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.2",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nlibceph: fix OOB read in decode_watchers() via missing bounds check\n\nceph_start_decoding() validates that struct_len bytes remain in the\nbuffer after the encoding header, but accepts struct_len=0 as valid:\nceph_decode_need(p, end, 0, bad) always passes. When a malicious or\ncompromised OSD sends an obj_list_watch_response_t reply with\nstruct_len=0, ceph_start_decoding() returns success with p == end,\nleaving zero bytes guaranteed for subsequent reads.\n\nThe immediately following ceph_decode_32(p) in decode_watchers() has\nno preceding bounds check. With p == end this is a 4-byte read past\nthe validated buffer boundary. The garbage value is then passed\ndirectly to kzalloc_objs() as the watcher count.\n\nThe sibling function decode_watcher() already uses the safe variants\n(ceph_decode_copy_safe, ceph_decode_64_safe, ceph_decode_skip_32)\nafter its own ceph_start_decoding() call. decode_watchers() is the\nonly site that uses the bare variant, confirming an oversight.\n\nFix by replacing ceph_decode_32(p) with ceph_decode_32_safe(p, end,\n*num_watchers, bad), consistent with the established pattern.\n\nAttacker model: a malicious or compromised OSD in a multi-tenant Ceph\ndeployment (e.g. cloud) can trigger this against any kernel client\nthat calls CEPH_OSD_OP_LIST_WATCHERS, without any further privileges\nbeyond OSD session establishment.\n\n[ idryomov: trim changelog ]"
    }
  ],
  "id": "CVE-2026-80557",
  "lastModified": "2026-08-27T13:18:40.360",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "NETWORK",
          "availabilityImpact": "HIGH",
          "baseScore": 9.8,
          "baseSeverity": "CRITICAL",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "HIGH",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 3.9,
        "impactScore": 5.9,
        "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "type": "Secondary"
      }
    ]
  },
  "published": "2026-08-26T15:17:10.400",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/00ead17c7de137a692edee59f2772e6af687e8eb"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/1c824e7c75bb4adf19553dd4ea944a5d83096be8"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/7130d94846dadbb97b6b7f4d78a3a7bba6e3daa1"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/85479b7d65b4ebcb07fbbe57230976793974ab4a"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/c59219a6b62d74936963983e5815524c3de8dd79"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/cb8246e5846dbbe34930903a90c7a90dd8e5910b"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/eab3eeb68bfc639d74f27256f05546af5c4f787d"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/f161be39201eb5f9b1f58fb8f90b8a9cd3931eb6"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Received"
}

GHSA-J5WF-CPJP-5VX9

Vulnerability from github – Published: 2026-08-27 06:31 – Updated: 2026-08-27 15:31

Details

In the Linux kernel, the following vulnerability has been resolved:

libceph: fix OOB read in decode_watchers() via missing bounds check

ceph_start_decoding() validates that struct_len bytes remain in the buffer after the encoding header, but accepts struct_len=0 as valid: ceph_decode_need(p, end, 0, bad) always passes. When a malicious or compromised OSD sends an obj_list_watch_response_t reply with struct_len=0, ceph_start_decoding() returns success with p == end, leaving zero bytes guaranteed for subsequent reads.

The immediately following ceph_decode_32(p) in decode_watchers() has no preceding bounds check. With p == end this is a 4-byte read past the validated buffer boundary. The garbage value is then passed directly to kzalloc_objs() as the watcher count.

The sibling function decode_watcher() already uses the safe variants (ceph_decode_copy_safe, ceph_decode_64_safe, ceph_decode_skip_32) after its own ceph_start_decoding() call. decode_watchers() is the only site that uses the bare variant, confirming an oversight.

Fix by replacing ceph_decode_32(p) with ceph_decode_32_safe(p, end, *num_watchers, bad), consistent with the established pattern.

Attacker model: a malicious or compromised OSD in a multi-tenant Ceph deployment (e.g. cloud) can trigger this against any kernel client that calls CEPH_OSD_OP_LIST_WATCHERS, without any further privileges beyond OSD session establishment.

[ idryomov: trim changelog ]

Severity

9.8 (Critical)


                  
                    CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Show details on source website

JSON

To clipboard

{
  "affected": [],
  "aliases": [
    "CVE-2026-80557"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-08-26T15:17:10Z",
    "severity": "CRITICAL"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nlibceph: fix OOB read in decode_watchers() via missing bounds check\n\nceph_start_decoding() validates that struct_len bytes remain in the\nbuffer after the encoding header, but accepts struct_len=0 as valid:\nceph_decode_need(p, end, 0, bad) always passes. When a malicious or\ncompromised OSD sends an obj_list_watch_response_t reply with\nstruct_len=0, ceph_start_decoding() returns success with p == end,\nleaving zero bytes guaranteed for subsequent reads.\n\nThe immediately following ceph_decode_32(p) in decode_watchers() has\nno preceding bounds check. With p == end this is a 4-byte read past\nthe validated buffer boundary. The garbage value is then passed\ndirectly to kzalloc_objs() as the watcher count.\n\nThe sibling function decode_watcher() already uses the safe variants\n(ceph_decode_copy_safe, ceph_decode_64_safe, ceph_decode_skip_32)\nafter its own ceph_start_decoding() call. decode_watchers() is the\nonly site that uses the bare variant, confirming an oversight.\n\nFix by replacing ceph_decode_32(p) with ceph_decode_32_safe(p, end,\n*num_watchers, bad), consistent with the established pattern.\n\nAttacker model: a malicious or compromised OSD in a multi-tenant Ceph\ndeployment (e.g. cloud) can trigger this against any kernel client\nthat calls CEPH_OSD_OP_LIST_WATCHERS, without any further privileges\nbeyond OSD session establishment.\n\n[ idryomov: trim changelog ]",
  "id": "GHSA-j5wf-cpjp-5vx9",
  "modified": "2026-08-27T15:31:32Z",
  "published": "2026-08-27T06:31:32Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-80557"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/00ead17c7de137a692edee59f2772e6af687e8eb"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/1c824e7c75bb4adf19553dd4ea944a5d83096be8"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/7130d94846dadbb97b6b7f4d78a3a7bba6e3daa1"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/85479b7d65b4ebcb07fbbe57230976793974ab4a"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/c59219a6b62d74936963983e5815524c3de8dd79"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/cb8246e5846dbbe34930903a90c7a90dd8e5910b"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/eab3eeb68bfc639d74f27256f05546af5c4f787d"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/f161be39201eb5f9b1f58fb8f90b8a9cd3931eb6"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ]
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.

Action not permitted

CVE-2026-80557 (GCVE-0-2026-80557)

FKIE_CVE-2026-80557

GHSA-J5WF-CPJP-5VX9

Tags

Sightings

Nomenclature