Vulnerability Snapshot
CVE-2026-31402 is rated CRITICAL — exploitation is trivial or already observed in the wild and impact is severe. Patch immediately, not on the next maintenance window.
Affected technology: linux_kernel.
Executive Summary
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
Why It Matters
CVE-2026-31402 is rated CRITICAL severity, requiring immediate attention from security teams.
CVSS Base Score: 9.8/10
EPSS (Exploit Prediction): 0.2% probability of exploitation in the next 30 days.
Affected Technologies
Vendors: linux
Products: linux_kernel
🛡️What Defenders Should Check
Use Vulnios to continuously monitor your exposure to CVE-2026-31402 and similar vulnerabilities.
References & Sources
How Vulnios Detects This
Vulnios scans for this vulnerability using Trivy and Grype for CVE matching against your container images and OS package manifests. Run a scan against your environment to see whether you are exposed; findings are linked back to the original CVE record so triage starts with the patch path already known.
AI Security Advisor
Powered by Gemini
Get AI-powered security recommendations tailored to this specific threat — including risk assessment, detection guidance, MITRE ATT&CK mapping, and actionable remediation steps.
Affected Products
Sources
Related Threat Alerts
- Critical Vulnerability: CVE-2026-43378 — linux — linux_kernel
- Critical Vulnerability: CVE-2026-31405 — linux — linux_kernel
- Critical Vulnerability: CVE-2026-43114 — linux — linux_kernel
- Critical Vulnerability: CVE-2026-43117 — linux — linux_kernel
- Critical Vulnerability: CVE-2026-43186 — linux — linux_kernel
- Critical Vulnerability: CVE-2026-43208 — linux — linux_kernel
Frequently Asked Questions
What is CVE-2026-31402?
CVE-2026-31402 is a critical-severity vulnerability tracked under the Common Vulnerabilities and Exposures program. 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_R
Am I affected?
Check whether your environment runs linux_kernel. If you operate any of those, treat yourself as in scope until you have evidence otherwise. A Vulnios scan will identify the exact assets carrying the affected version.
How urgent is the response?
Critical: do not wait for your normal patch cycle. Verify exposure today, apply the vendor patch immediately, and add detection rules for any post-exploit indicators.
How do I remediate?
Apply the vendor patch listed in the upstream advisory linked under Sources. If the patch is not yet available, follow the vendor-supplied workaround (often a config flag or feature disable) and add detections for the published exploit pattern in your SIEM. Re-scan after the patch lands to confirm the finding clears.
Where can I track exploitation activity?
Watch CISA's Known Exploited Vulnerabilities catalog for CVE-2026-31402. Cross-reference with public exploit databases and your own SIEM/IDS for indicator-of-compromise patterns. Vulnios tracks KEV status automatically and surfaces it on the asset findings view.
How does Vulnios help with this?
Vulnios continuously cross-references your asset inventory against the live CVE feed (NVD, vendor advisories, CISA KEV, and curated OSINT). When a new CVE matches your environment, you get a prioritized finding with the severity, KEV status, exploit-prediction (EPSS), and a direct path to the vendor patch. You can start a free scan from the homepage.
Protect Your Organization
Monitor CVEs, scan for vulnerabilities, and get real-time threat alerts — all in one platform.
Get instant alerts on Telegram
Join our public channel for real-time critical CVE alerts.
Follow @vulnios