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VulnerabilityPublished Updated

CVE-2026-64046: Linux kernel · net: tls: prevent chain-after-chain in plain text SG

Affects Linux kernelSource CVE Database V5

0

Not known to be exploited · CVSS 9.8 Critical · fixed in ff26a0e8377dec07e4a7230db7675bed1b9a6d03 : patch Linux kernel as a priority.

Data as of 26 Oct 2026, 13:47 UTC

CVSS 3.1 base score
9.8Critical
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.5% chance of exploitation in 30 days – higher than 43% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CISA SSVC
Exploitation
No evidence of active exploitation and no public proof of concept
Automatable
Attackers can reliably automate steps 1–4 of the kill chain
Technical impact
Total control over the software or total information disclosure

CISA SSVC assessment, 2026-10-16.

Patch
Available – fixed in ff26a0e8377dec07e4a7230db7675bed1b9a6d03, b9c015ef1a7bf1e8dc67f21c6381f36deb2c3a36, af855f4c966afafef74faf8390c7b86568c0d46d +6
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 19 Jul 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

What to do

Upgrade to a fixed release listed under Affected software.

Affected software

ProductAffectedFixed in
LinuxLinuxAffected
  • >=5.4.14 <5.5
Fixed in
  • ff26a0e8377dec07e4a7230db7675bed1b9a6d03
  • b9c015ef1a7bf1e8dc67f21c6381f36deb2c3a36
  • af855f4c966afafef74faf8390c7b86568c0d46d
  • acdc12b71c9aa4be5dcd2c8062753c6d2033e235
  • 410351158dfef2d67fea6603680b3a6013c6ed9d
  • 91359966e247c0244c66d50bbb8e74aefa4321c3
  • 929b1548e63ac72e104c07d8ee8cbbeeba2fa89a
  • 49a5faaa471ddcd37b6893970c9916eb836e7c31
  • 5.5
LinuxLinuxAffected
  • =5.5
Fixed in–

Description

In the Linux kernel, the following vulnerability has been resolved: net: tls: prevent chain-after-chain in plain text SG Sashiko points out that if end = 0 (start != 0) the current code will create a chain link to content type right after the wrap link: This would create a chain where the wrap link points directly to another chain link. The scatterlist API sg_next iterator does not recursively resolve consecutive chain links. meaning this is illegal input to crypto. The wrapping link is unnecessary if end = 0. end is the entry after the last one used so end = 0 means there's nothing pushed after the wrap: end start i v v v [ ]...[ ][ d ][ d ][ d ][ d ][rsv for wrap] Skip the wrapping in this case. TLS 1.3 can use the "wrapping slot" for it's chaining if end = 0. This avoids the chain-after-chain. Move the wrap chaining before marking END and chaining off content type, that feels like more logical ordering to me, but should not matter from functional perspective.

References

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