CVE-2026-31402: In the Linux kernel, the following vulnerability has been resolved: nfsd: fix heap overflow in NFSv4.0 LOCK r

Q: How do I fix CVE-2026-31402?

linux kernel: upgrade to 5.10.253, 6.1.167, 6.6.130, 6.12.78, 6.18.20, 6.19.10. Exact commands for each OS are on this page.

Q: Is CVE-2026-31402 being exploited?

CVE-2026-31402 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2026-31402 affect?

CVE-2026-31402 affects linux kernel. Severity is critical (CVSS 9.8). 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

Q: How urgent is CVE-2026-31402?

Priority 64/100. Critical severity; CISA SSVC: automatable with total technical impact; Remotely exploitable, no login, no user action; On your watchlist

This week

CRITICAL 9.8REMOTEWATCHLISTUPGRADE

CVE-2026-31402 is a critical-severity flaw (CVSS 9.8) affecting linux kernel. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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_LIM

Why this priority

Critical severity
CISA SSVC: automatable with total technical impact
Remotely exploitable, no login, no user action
On your watchlist

A fixed release or distro patch exists.

Risk facts

CVSS score	9.8 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	1.2% (top 32%)
CISA exploited list	No
Weakness	CWE-787, CWE-122
Published	2026-04-03
Last modified	2026-10-19

Publisher (CNA): kernel.org · Vendor: linux

Last updated 2026-10-19 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-04-03 16:16 UTCPublished CVE record published
2026-10-19 19:17 UTCUpdated Record last modified

linux linux kernel UPGRADE

Affected: >= 2.6.12.1 and < 5.10.253 · >= 5.11 and < 6.1.167 · >= 6.2 and < 6.6.130 · >= 6.7 and < 6.12.78 · >= 6.13 and < 6.18.20 · >= 6.19 and < 6.19.10 · 2.6.12 · 2.6.12 rc2

Fixed in: 5.10.253, 6.1.167, 6.6.130, 6.12.78, 6.18.20, 6.19.10

Safe to downgrade to: no unaffected older release

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

Exact fixes by distribution

Fedora 46 · python-googleapis-common-protos · FIXED · 1.75.5-1.fc46~bootstrap · FEDORA-2026-d911c4c4e6 · source

sudo dnf upgrade --advisory=FEDORA-2026-d911c4c4e6

Fedora ELN · see advisory · FIXED · FEDORA-2026-e3987c278f · source

sudo dnf upgrade --advisory=FEDORA-2026-e3987c278f

Debian 12 · linux · FIXED · 6.1.170-1

sudo apt update && sudo apt install --only-upgrade linux dpkg --compare-versions "$(dpkg-query -W -f='${Version}' linux)" ge "6.1.170-1" && echo PATCHED || echo STILL-VULNERABLE

Debian 13 · linux · FIXED · 6.12.85-1

sudo apt update && sudo apt install --only-upgrade linux dpkg --compare-versions "$(dpkg-query -W -f='${Version}' linux)" ge "6.12.85-1" && echo PATCHED || echo STILL-VULNERABLE

RHEL 10 · kernel · FIXED · kernel-6.12.0-124.55.1.el10_1

sudo dnf upgrade --advisory=RHSA-2026:13566 rpm -q kernel

RHEL 10.0 Extended Update Support · kernel · FIXED · kernel-6.12.0-55.72.1.el10_0

sudo dnf upgrade --advisory=RHSA-2026:15883 rpm -q kernel

RHEL 6 Extended Lifecycle Support - EXTENSION · kernel · FIXED · kernel-2.6.32-754.60.1.el6

sudo dnf upgrade --advisory=RHSA-2026:14823 rpm -q kernel

RHEL 7 Extended Lifecycle Support · kernel-rt · FIXED · kernel-rt-3.10.0-1160.149.1.rt56.1301.el7

sudo dnf upgrade --advisory=RHSA-2026:14869 rpm -q kernel-rt

RHEL 7 Extended Lifecycle Support · kernel · FIXED · kernel-3.10.0-1160.149.1.el7

sudo dnf upgrade --advisory=RHSA-2026:14925 rpm -q kernel

Amazon Linux 2023 · see advisory · FIXED · ALAS2023-2026-1681 · source

sudo dnf update --advisory=ALAS2023-2026-1681

Public exploits and detection

Public code exists for this CVE. Treat unpatched systems as at risk, and only run PoCs in a lab.

GitHub PoC: 0xBlackash/CVE-2026-31402 (0 stars)
Write-up: cert-portal.siemens.com/productcert/html/ssa-019113.html
Write-up: cert-portal.siemens.com/productcert/html/ssa-082556.html
Write-up: cert-portal.siemens.com/productcert/html/ssa-457936.html

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-31402?

linux kernel: upgrade to 5.10.253, 6.1.167, 6.6.130, 6.12.78, 6.18.20, 6.19.10. Exact commands for each OS are on this page.

Is CVE-2026-31402 being exploited?

CVE-2026-31402 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-31402 affect?

CVE-2026-31402 affects linux kernel. Severity is critical (CVSS 9.8). 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

How urgent is CVE-2026-31402?

Priority 64/100. Critical severity; CISA SSVC: automatable with total technical impact; Remotely exploitable, no login, no user action; On your watchlist

Software pages

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References

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