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CVE-2026-31636

Critical Vulnerability: CVE-2026-31636 — linux — linux_kernel

In the Linux kernel, the following vulnerability has been resolved: rxrpc: fix RESPONSE authenticator parser OOB read rxgk_verify_authenticator() copies auth_len bytes into a temporary buffer and then passes p + auth_len as the parser limit to rxgk_do_verify_authenticator(). Since p is a __be32 *, that inflates the parser end pointer by a factor of four and lets malformed RESPONSE authenticators read past the kmalloc() buffer. Decoded from the original latest-net reproduction logs with script

Thursday, May 14, 2026linuxVulnios Threat Intelligence
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Vulnerability Snapshot

CVE-2026-31636 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:

rxrpc: fix RESPONSE authenticator parser OOB read

rxgk_verify_authenticator() copies auth_len bytes into a temporary

buffer and then passes p + auth_len as the parser limit to

rxgk_do_verify_authenticator(). Since p is a __be32 *, that inflates the

parser end pointer by a factor of four and lets malformed RESPONSE

authenticators read past the kmalloc() buffer.

Decoded from the original latest-net reproduction logs with

scripts/decode_stacktrace.sh:

BUG: KASAN: slab-out-of-bounds in rxgk_verify_response()

Call Trace:

dump_stack_lvl() [lib/dump_stack.c:123]

print_report() [mm/kasan/report.c:379 mm/kasan/report.c:482]

kasan_report() [mm/kasan/report.c:597]

rxgk_verify_response()

[net/rxrpc/rxgk.c:1103 net/rxrpc/rxgk.c:1167

net/rxrpc/rxgk.c:1274]

rxrpc_process_connection()

[net/rxrpc/conn_event.c:266 net/rxrpc/conn_event.c:364

net/rxrpc/conn_event.c:386]

process_one_work() [kernel/workqueue.c:3281]

Why It Matters

CVE-2026-31636 is rated CRITICAL severity, requiring immediate attention from security teams.

CVSS Base Score: 9.1/10

Affected Technologies

Vendors: linux

Products: linux_kernel

🛡️What Defenders Should Check

  • Check if you are affected — Review your asset inventory for products listed in CVE-2026-31636.
  • Apply available patches — Visit vendor advisories for the latest security updates.
  • Monitor for exploitation — Check your SIEM/IDS logs for related indicators.

    • Use Vulnios to continuously monitor your exposure to CVE-2026-31636 and similar vulnerabilities.

    References & Sources

  • https://git.kernel.org/stable/c/20a188775a9a9982d1987e12660d9b44b40a6c99
  • https://git.kernel.org/stable/c/3e3138007887504ee9206d0bfb5acb062c600025
  • https://git.kernel.org/stable/c/7875f3d9777bd4e9892c4db830571ab8ac2044c0

    • 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.

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    Affected Products

    linux_kernel

    Sources

    Related Threat Alerts

    Frequently Asked Questions

    What is CVE-2026-31636?

    CVE-2026-31636 is a critical-severity vulnerability tracked under the Common Vulnerabilities and Exposures program. In the Linux kernel, the following vulnerability has been resolved:

    rxrpc: fix RESPONSE authenticator parser OOB read

    rxgk_verify_authenticator() copies auth_len bytes into a temporary

    buffer and th

    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-2026-31636. 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.

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