CVE-2025-21967 (GCVE-0-2025-21967)

Vulnerability from cvelistv5 – Published: 2025-04-01 15:47 – Updated: 2026-08-05 11:55
VLAI
Title
ksmbd: fix use-after-free in ksmbd_free_work_struct
Summary
In the Linux kernel, the following vulnerability has been resolved: ksmbd: fix use-after-free in ksmbd_free_work_struct ->interim_entry of ksmbd_work could be deleted after oplock is freed. We don't need to manage it with linked list. The interim request could be immediately sent whenever a oplock break wait is needed.
Severity
8.8 (High)
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
7.8 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
SSVC
Exploitation: none Automatable: no Technical Impact: total
CISA Coordinator (v2.0.3)
CWE
Assigner
References
Impacted products
Vendor Product Version
Linux Linux Affected: 0626e6641f6b467447c81dd7678a69c66f7746cf , < fb776765bfc21d5e4ed03bb3d4406c2b86ff1ac3 (git)
Affected: 0626e6641f6b467447c81dd7678a69c66f7746cf , < 62746ae3f5414244a96293e3b017be637b641280 (git)
Affected: 0626e6641f6b467447c81dd7678a69c66f7746cf , < eb51f6f59d19b92f6fe84d3873f958495ab32f0a (git)
Affected: 0626e6641f6b467447c81dd7678a69c66f7746cf , < bb39ed47065455604729404729d9116868638d31 (git)
Create a notification for this product.
Linux Linux Affected: 5.15
Unaffected: 0 , < 5.15 (semver)
Unaffected: 6.6.84 , ≤ 6.6.* (semver)
Unaffected: 6.12.20 , ≤ 6.12.* (semver)
Unaffected: 6.13.8 , ≤ 6.13.* (semver)
Unaffected: 6.14 , ≤ * (original_commit_for_fix)
Create a notification for this product.
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    "redhat_vex": {
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      "current_release_date": "2026-06-29T20:39:57+00:00",
      "cve": "CVE-2025-21967",
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      "product_status:known_not_affected": "274",
      "source": "Red Hat CSAF VEX",
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      "title": "kernel: ksmbd: fix use-after-free in ksmbd_free_work_struct",
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      "title": "SUSE CVE CVE-2025-21967",
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      "version": "13"
    },
    "vulnrichment": {
      "containers": "{\"adp\": [{\"title\": \"CISA ADP Vulnrichment\", \"metrics\": [{\"cvssV3_1\": {\"scope\": \"UNCHANGED\", \"version\": \"3.1\", \"baseScore\": 7.8, \"attackVector\": \"LOCAL\", \"baseSeverity\": \"HIGH\", \"vectorString\": \"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H\", \"integrityImpact\": \"HIGH\", \"userInteraction\": \"NONE\", \"attackComplexity\": \"LOW\", \"availabilityImpact\": \"HIGH\", \"privilegesRequired\": \"LOW\", \"confidentialityImpact\": \"HIGH\"}}, {\"other\": {\"type\": \"ssvc\", \"content\": {\"id\": \"CVE-2025-21967\", \"role\": \"CISA Coordinator\", \"options\": [{\"Exploitation\": \"none\"}, {\"Automatable\": \"no\"}, {\"Technical Impact\": \"total\"}], \"version\": \"2.0.3\", \"timestamp\": \"2025-04-16T13:14:51.011092Z\"}}}], \"problemTypes\": [{\"descriptions\": [{\"lang\": \"en\", \"type\": \"CWE\", \"cweId\": \"CWE-416\", \"description\": \"CWE-416 Use After Free\"}]}], \"providerMetadata\": {\"orgId\": \"134c704f-9b21-4f2e-91b3-4a467353bcc0\", \"shortName\": \"CISA-ADP\", \"dateUpdated\": \"2025-04-16T13:14:52.575Z\"}}], \"cna\": {\"title\": \"ksmbd: fix use-after-free in ksmbd_free_work_struct\", \"metrics\": [{\"cvssV3_1\": {\"version\": \"3.1\", \"baseScore\": 8.8, \"baseSeverity\": \"HIGH\", \"vectorString\": \"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H\"}, \"scenarios\": [{\"lang\": \"en\", \"value\": \"AV:N - ksmbd is the in-kernel SMB server listening on TCP/445, and the entire trigger sequence (a CREATE requesting a batch oplock/write lease on one connection, a conflicting overwrite CREATE plus a close/disconnect on a second) is driven purely by remote SMB2 protocol traffic. No local access to the target is required.\\nAC:L - The double `list_add` of the same `work-\u003einterim_entry` in `smb2_open()` is deterministic, not racy, and the attacker owns both connections so it chooses exactly when the peer\u0027s `oplock_info` is released relative to `ksmbd_free_work_struct()`, and can loop the sequence indefinitely. Per guidance, an attacker-created ordering and a use-after-free are Low.\\nPR:L - Reaching `smb_grant_oplock()`/`smb_break_all_oplock()` requires a completed SESSION_SETUP, TREE_CONNECT and SMB2 CREATE, so an authenticated but otherwise unprivileged share account (including a mapped guest) is needed. This matches the scoring of the sibling post-authentication ksmbd oplock UAFs.\\nUI:N - The attacker drives every step from its own two SMB sessions \\u2014 take the oplock, issue the conflicting overwrite CREATE, then close or drop the first connection. No administrator or other client has to do anything.\\nS:U - The list corruption and its consequences stay entirely within the kernel\u0027s own security authority; no VM, IOMMU, or sandbox boundary is crossed.\\nC:H - The stale `interim_list` head lets `smb2_lease_break_noti()` treat reclaimed heap memory as a `struct ksmbd_work`, dereferencing its `conn`, `sess`, and `request_buf` fields, and `smb2_send_interim_resp()` then transmits data derived from that object back to the attacker \\u2014 an arbitrary kernel memory disclosure primitive after a heap spray.\\nI:H - `list_del()` in `ksmbd_free_work_struct()` writes two attacker-influenced kernel heap pointers at a fixed offset into a freed kmalloc-256 slot that the attacker can reclaim with a chosen object, and the fake-`ksmbd_work` path yields further controlled pointer writes and indirect calls, giving control-flow hijack.\\nA:H - Even unweaponized, the `list_del` on freed memory trips `CONFIG_DEBUG_LIST`/`BUG()` or silently corrupts the slab, and walking the dangling `interim_list` oopses the ksmbd worker; the attacker can repeat it at will to keep the file server down.\"}]}], \"affected\": [{\"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\", \"vendor\": \"Linux\", \"product\": \"Linux\", \"versions\": [{\"status\": \"affected\", \"version\": \"0626e6641f6b467447c81dd7678a69c66f7746cf\", \"lessThan\": \"fb776765bfc21d5e4ed03bb3d4406c2b86ff1ac3\", \"versionType\": \"git\"}, {\"status\": \"affected\", \"version\": \"0626e6641f6b467447c81dd7678a69c66f7746cf\", \"lessThan\": \"62746ae3f5414244a96293e3b017be637b641280\", \"versionType\": \"git\"}, {\"status\": \"affected\", \"version\": \"0626e6641f6b467447c81dd7678a69c66f7746cf\", \"lessThan\": \"eb51f6f59d19b92f6fe84d3873f958495ab32f0a\", \"versionType\": \"git\"}, {\"status\": \"affected\", \"version\": \"0626e6641f6b467447c81dd7678a69c66f7746cf\", \"lessThan\": \"bb39ed47065455604729404729d9116868638d31\", \"versionType\": \"git\"}], \"programFiles\": [\"fs/smb/server/ksmbd_work.c\", \"fs/smb/server/ksmbd_work.h\", \"fs/smb/server/oplock.c\", \"fs/smb/server/oplock.h\"], \"defaultStatus\": \"unaffected\"}, {\"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\", \"vendor\": \"Linux\", \"product\": \"Linux\", \"versions\": [{\"status\": \"affected\", \"version\": \"5.15\"}, {\"status\": \"unaffected\", \"version\": \"0\", \"lessThan\": \"5.15\", \"versionType\": \"semver\"}, {\"status\": \"unaffected\", \"version\": \"6.6.84\", \"versionType\": \"semver\", \"lessThanOrEqual\": \"6.6.*\"}, {\"status\": \"unaffected\", \"version\": \"6.12.20\", \"versionType\": \"semver\", \"lessThanOrEqual\": \"6.12.*\"}, {\"status\": \"unaffected\", \"version\": \"6.13.8\", \"versionType\": \"semver\", \"lessThanOrEqual\": \"6.13.*\"}, {\"status\": \"unaffected\", \"version\": \"6.14\", \"versionType\": \"original_commit_for_fix\", \"lessThanOrEqual\": \"*\"}], \"programFiles\": [\"fs/smb/server/ksmbd_work.c\", \"fs/smb/server/ksmbd_work.h\", \"fs/smb/server/oplock.c\", \"fs/smb/server/oplock.h\"], \"defaultStatus\": \"affected\"}], \"references\": [{\"url\": \"https://git.kernel.org/stable/c/fb776765bfc21d5e4ed03bb3d4406c2b86ff1ac3\"}, {\"url\": \"https://git.kernel.org/stable/c/62746ae3f5414244a96293e3b017be637b641280\"}, {\"url\": \"https://git.kernel.org/stable/c/eb51f6f59d19b92f6fe84d3873f958495ab32f0a\"}, {\"url\": \"https://git.kernel.org/stable/c/bb39ed47065455604729404729d9116868638d31\"}], \"x_generator\": {\"engine\": \"bippy-1.2.0\"}, \"descriptions\": [{\"lang\": \"en\", \"value\": \"In the Linux kernel, the following vulnerability has been resolved:\\n\\nksmbd: fix use-after-free in ksmbd_free_work_struct\\n\\n-\u003einterim_entry of ksmbd_work could be deleted after oplock is freed.\\nWe don\u0027t need to manage it with linked list. The interim request could be\\nimmediately sent whenever a oplock break wait is needed.\"}], \"cpeApplicability\": [{\"nodes\": [{\"negate\": false, \"cpeMatch\": [{\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"6.6.84\", \"versionStartIncluding\": \"5.15\"}, {\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"6.12.20\", \"versionStartIncluding\": \"5.15\"}, {\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"6.13.8\", \"versionStartIncluding\": \"5.15\"}, {\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"6.14\", \"versionStartIncluding\": \"5.15\"}], \"operator\": \"OR\"}]}], \"providerMetadata\": {\"orgId\": \"416baaa9-dc9f-4396-8d5f-8c081fb06d67\", \"shortName\": \"Linux\", \"dateUpdated\": \"2026-08-05T11:55:43.302Z\"}}}",
      "cveMetadata": "{\"cveId\": \"CVE-2025-21967\", \"state\": \"PUBLISHED\", \"dateUpdated\": \"2026-08-05T11:55:43.302Z\", \"dateReserved\": \"2024-12-29T08:45:45.796Z\", \"assignerOrgId\": \"416baaa9-dc9f-4396-8d5f-8c081fb06d67\", \"datePublished\": \"2025-04-01T15:47:02.364Z\", \"assignerShortName\": \"Linux\"}",
      "dataType": "CVE_RECORD",
      "dataVersion": "5.2"
    }
  }
}



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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

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.