CVE-2026-31402

CRITICAL EPSS 46.3%
Published Apr 3, 20262mo ago · Modified Jun 17, 20261w ago
9.8 CVSS 3.1
Critical
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Published Apr 3, 2026 2mo ago
Last Modified Jun 17, 2026 1w ago

Description

In the Linux kernel, the following vulnerability has been resolved: nfsd: fix heap overflow in NFSv4.0 LOCK replay cache The NFSv4.0 replay cache uses a fixed 112-byte inline buffer (rp_ibuf[NFSD4_REPLAY_ISIZE]) to store encoded operation responses. This size was calculated based on OPEN responses and does not account for LOCK denied responses, which include the conflicting lock owner as a variable-length field up to 1024 bytes (NFS4_OPAQUE_LIMIT). When a LOCK operation is denied due to a conflict with an existing lock that has a large owner, nfsd4_encode_operation() copies the full encoded response into the undersized replay buffer via read_bytes_from_xdr_buf() with no bounds check. This results in a slab-out-of-bounds write of up to 944 bytes past the end of the buffer, corrupting adjacent heap memory. This can be triggered remotely by an unauthenticated attacker with two cooperating NFSv4.0 clients: one sets a lock with a large owner string, then the other requests a conflicting lock to provoke the denial. We could fix this by increasing NFSD4_REPLAY_ISIZE to allow for a full opaque, but that would increase the size of every stateowner, when most lockowners are not that large. Instead, fix this by checking the encoded response length against NFSD4_REPLAY_ISIZE before copying into the replay buffer. If the response is too large, set rp_buflen to 0 to skip caching the replay payload. The status is still cached, and the client already received the correct response on the original request.

CVSS Details

Base Score
9.8
Exploitability
3.9
Impact
5.9
Vector string
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Attack Vector Network
Attack Complexity Low
Privileges Required None
User Interaction None
Scope Unchanged
Confidentiality High
Integrity High
Availability High

Threat Intelligence

EPSS Exploit Probability
46.3% percentile
Exploit & Patch Status
No Known Exploit
Patch Available

Weaknesses 1

CWE-787 Out-of-bounds Write Memory Safety

Affected Products 15

VendorProductVersionRange
linuxlinux_kernel*≥2.6.12.1  –  <5.10.253
linuxlinux_kernel*≥5.11  –  <6.1.167
linuxlinux_kernel*≥6.2  –  <6.6.130
linuxlinux_kernel*≥6.7  –  <6.12.78
linuxlinux_kernel*≥6.13  –  <6.18.20
linuxlinux_kernel*≥6.19  –  <6.19.10
linuxlinux_kernel2.6.12any
linuxlinux_kernel2.6.12any
linuxlinux_kernel2.6.12any
linuxlinux_kernel2.6.12any
linuxlinux_kernel2.6.12any
linuxlinux_kernel7.0any
linuxlinux_kernel7.0any
linuxlinux_kernel7.0any
linuxlinux_kernel7.0any

References 7

  • git.kernel.org https://git.kernel.org/stable/c/0f0e2a54a31a7f9ad2915db99156114872317388
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/5133b61aaf437e5f25b1b396b14242a6bb0508e2
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/8afb437ea1f70cacb4bbdf11771fb5c4d720b965
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/ae8498337dfdfda71bdd0b807c9a23a126011d76
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/c9452c0797c95cf2378170df96cf4f4b3bca7eff
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/dad0c3c0a8e5d1d6eb0fc455694ce3e25e6c57d0
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/f9fcb4441f6c02bb20c2eb340101e27dfe23607c
    Patch

Remediation

  • git.kernel.org https://git.kernel.org/stable/c/0f0e2a54a31a7f9ad2915db99156114872317388
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/5133b61aaf437e5f25b1b396b14242a6bb0508e2
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/8afb437ea1f70cacb4bbdf11771fb5c4d720b965
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/ae8498337dfdfda71bdd0b807c9a23a126011d76
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/c9452c0797c95cf2378170df96cf4f4b3bca7eff
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/dad0c3c0a8e5d1d6eb0fc455694ce3e25e6c57d0
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/f9fcb4441f6c02bb20c2eb340101e27dfe23607c
    Patch