CVE-2026-92518 (GCVE-0-2026-92518)

Vulnerability from cvelistv5 – Published: 2026-09-17 16:10 – Updated: 2026-09-18 17:55
VLAI
Title
riscv, bpf: Fix kernel stack corruption in tailcall with CFI
Summary
In the Linux kernel, the following vulnerability has been resolved: riscv, bpf: Fix kernel stack corruption in tailcall with CFI When CONFIG_CFI_CLANG is enabled, prog->bpf_func already skips the kcfi instruction during setup. Including it again in the tailcall jump offset causes it to jump over an extra 4 bytes, skipping the stack pointer adjustment, which will result in kernel stack corruption.
Severity
7.8 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 30a59cc79754fd9ff3f41b7ee2eb21da85988548 , < 34b1bb33a025787e05f966e74de18cd36276f801 (git)
Affected: 30a59cc79754fd9ff3f41b7ee2eb21da85988548 , < a6e11a81da3420fd37f1518d4f238c4d5784086e (git)
Affected: 30a59cc79754fd9ff3f41b7ee2eb21da85988548 , < 52fb1756ea1d2759dfef2d86245be00b05dac3a2 (git)
Affected: fe5b68fdcec0f3d97a32f4c4acfef59cf90718f7 (git)
Affected: 6.11.6 , < 6.12 (semver)
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Linux Linux Affected: 6.12
Unaffected: 0 , < 6.12 (semver)
Unaffected: 6.18.52 , ≤ 6.18.* (semver)
Unaffected: 7.2.6 , ≤ 7.2.* (semver)
Unaffected: 7.3-rc1 , ≤ * (original_commit_for_fix)
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "arch/riscv/net/bpf_jit_comp64.c"
          ],
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          "vendor": "Linux",
          "versions": [
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              "versionType": "git"
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              "versionType": "git"
            },
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              "versionType": "git"
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          "vendor": "Linux",
          "versions": [
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              "version": "0",
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              "version": "6.18.52",
              "versionType": "semver"
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              "version": "7.2.6",
              "versionType": "semver"
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              "versionType": "original_commit_for_fix"
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      "cpeApplicability": [
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          "nodes": [
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                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.52",
                  "versionStartIncluding": "6.12",
                  "vulnerable": true
                },
                {
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                  "vulnerable": true
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              "negate": false,
              "operator": "OR"
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      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nriscv, bpf: Fix kernel stack corruption in tailcall with CFI\n\nWhen CONFIG_CFI_CLANG is enabled, prog-\u003ebpf_func already skips the kcfi\ninstruction during setup. Including it again in the tailcall jump offset\ncauses it to jump over an extra 4 bytes, skipping the stack pointer\nadjustment, which will result in kernel stack corruption."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 7.8,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:L - The attacker-controlled input is a BPF program that uses bpf_tail_call, loaded via bpf(BPF_PROG_LOAD) in __sys_bpf(). emit_bpf_tail_call() then calls __build_epilogue(true), which emits the miscomputed jalr; no remote protocol carries that bytecode.\nAC:L - On CONFIG_CFI, bpf_int_jit_compile() sets prog-\u003ebpf_func to ro_insns+cfi_get_offset() (skipping the kcfi word), while __build_epilogue() still adds RV_KCFI_NINSNS to the jalr immediate, so every tail call lands past the prologue addi-to-SP. The attacker loads the caller/callee and runs them; no race or uninfluenced layout is required.\nPR:L - bpf_prog_load() allows BPF_PROG_TYPE_SOCKET_FILTER without CAP_BPF when unprivileged BPF is enabled, BPF_MAP_TYPE_PROG_ARRAY is created without CAP_BPF, and bpf_base_func_proto() returns bpf_tail_call_proto before the CAP_PERFMON gate. Otherwise only CAP_BPF or a delegated BPF token is required, not init-namespace root.\nUI:N - The attacker loads both programs, updates the PROG_ARRAY, and runs the caller with bpf(BPF_PROG_TEST_RUN) (sk_filter_prog_ops.test_run = bpf_prog_test_run_skb) or setsockopt(SO_ATTACH_BPF) on a socket they own. No other user must mount, open, or click.\nS:U - The skipped stack allocation corrupts the host kernel stack of the thread running the JITed image (bpf_prog_test_run_skb or sk_filter_trim_cap). That is in-kernel memory corruption on the same authority, not a KVM/Xen guest-to-host or IOMMU boundary crossing.\nC:H - After the tailcall jalr skips emit_addi(SP, SP, -stack_adjust), bpf_jit_build_prologue() still does emit_addi(S5, SP, bpf_stack_adjust), so BPF_REG_FP addresses the kernel caller\u0027s frame. FP-relative LDX then reads saved return addresses and locals from that frame.\nI:H - The same missed SP subtract means prologue sd of RA/FP/S1\u2013S6 and BPF STX through S5 write into the kernel frame above SP. The callee epilogue then addi SP, SP, stack_adjust and jalr RA on that smashed frame, enabling a stack pivot and control-flow hijack.\nA:H - Returning from the tail-call target with SP still at the pre-BPF kernel SP, then adding stack_adjust in __build_epilogue(), misaligns the caller of bpf_prog_run so the kernel oopses or panics; any such crash is Availability High."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-09-18T17:55:36.191Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
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          "url": "https://git.kernel.org/stable/c/34b1bb33a025787e05f966e74de18cd36276f801"
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          "url": "https://git.kernel.org/stable/c/a6e11a81da3420fd37f1518d4f238c4d5784086e"
        },
        {
          "url": "https://git.kernel.org/stable/c/52fb1756ea1d2759dfef2d86245be00b05dac3a2"
        }
      ],
      "title": "riscv, bpf: Fix kernel stack corruption in tailcall with CFI",
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-92518",
    "datePublished": "2026-09-17T16:10:26.136Z",
    "dateReserved": "2026-09-16T12:21:13.873Z",
    "dateUpdated": "2026-09-18T17:55:36.191Z",
    "state": "PUBLISHED"
  },
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      "date": "2026-09-29",
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                "programFiles": [
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                ],
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        "descriptions": [
          {
            "lang": "en",
            "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nriscv, bpf: Fix kernel stack corruption in tailcall with CFI\n\nWhen CONFIG_CFI_CLANG is enabled, prog-\u003ebpf_func already skips the kcfi\ninstruction during setup. Including it again in the tailcall jump offset\ncauses it to jump over an extra 4 bytes, skipping the stack pointer\nadjustment, which will result in kernel stack corruption."
          }
        ],
        "id": "CVE-2026-92518",
        "lastModified": "2026-09-18T18:18:13.997",
        "metrics": {
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                "scope": "UNCHANGED",
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        "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "vulnStatus": "Received"
      }
    },
    "suse_vex": {
      "aggregate_severity": "important",
      "current_release_date": "2026-09-22T16:26:19Z",
      "cve": "CVE-2026-92518",
      "id": "CVE-2026-92518",
      "initial_release_date": "2026-09-22T16:26:19Z",
      "product_status:known_affected": "29",
      "product_status:known_not_affected": "318",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2026-92518",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2026-92518.json",
      "version": "2"
    }
  }
}



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  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.



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