CVE-2026-89536

Kernel memory corruption via TLS callback race

Published Sep 11, 2026 · Updated Sep 11, 2026

A use-after-free in Linux 6.5 SUNRPC client TLS handling allows attackers to corrupt memory during a handshake timeout or signal. xs_tls_handshake_sync drops the callback-owned lower-transport reference after tls_handshake_cancel loses to a completed request, while xs_tls_handshake_done can still store xprt_err and release that transport. The race requires a timeout or signal to overlap the completion callback; upstream material establishes freed-transport access but no remote control or specific crash or privilege outcome.

CVSS severityUnavailable
Unscored
EPSS probability0.63%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

A use-after-free in Linux 6.5 SUNRPC client TLS handling allows attackers to corrupt memory during a handshake timeout or signal. xs_tls_handshake_sync drops the callback-owned lower-transport reference after tls_handshake_cancel loses to a completed request, while xs_tls_handshake_done can still store xprt_err and release that transport. The race requires a timeout or signal to overlap the completion callback; upstream material establishes freed-transport access but no remote control or specific crash or privilege outcome.

The record

CVE
CVE-2026-89536
Published
Sep 11, 2026
Updated
Sep 11, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
Unavailable
Attack vector
Unavailable
Privileges
Unavailable

Timeline

How it unfolded

  1. Sep 11, 2026CVE publishedPublication date reported by the CVE source.
  2. Sep 11, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=6.5
  2. Affected versionversion=75eb6af7acdf566c68d61e98e67ee2f235201c02 <15431820f448e09f8029b670d5c82aa5917d4625
  3. Affected versionversion=75eb6af7acdf566c68d61e98e67ee2f235201c02 <1de391e8b94e31b45c19c16dbf315e294810c7de
  4. Affected versionversion=75eb6af7acdf566c68d61e98e67ee2f235201c02 <7fbb6d2ab0391eb8d1f1a68e6bc263ef02cea61b
  5. Affected versionversion=75eb6af7acdf566c68d61e98e67ee2f235201c02 <a89dd597458848b463d284b15e42a8078beeb046

What conditions does exploitation require?

Attack vectorUnavailable in this record.
Required privilegesUnavailable in this record.

What is affected?

The Linux Kernel Organization · Linuxversion=6.5; version=75eb6af7acdf566c68d61e98e67ee2f235201c02 <15431820f448e09f8029b670d5c82aa5917d4625; version=75eb6af7acdf566c68d61e98e67ee2f235201c02 <1de391e8b94e31b45c19c16dbf315e294810c7de; version=75eb6af7acdf566c68d61e98e67ee2f235201c02 <7fbb6d2ab0391eb8d1f1a68e6bc263ef02cea61b; version=75eb6af7acdf566c68d61e98e67ee2f235201c02 <a89dd597458848b463d284b15e42a8078beeb046

Published CVSS scores

No CVSS assessment is available in this record.

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
VectorUnavailable
PrivilegesUnavailable
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

No sourced classifications are available.

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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