CyberSecBulletin
CVE-2026-64046NVD status: Modified

In the Linux kernel, the following vulnerability has been resolved: net: tls: prevent…

Published Updated By the CyberSecBulletin desk

CVE-2026-64046 is a critical-severity improper input validation vulnerability in Linux, with a CVSS 3.1 base score of 9.8 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. The record lists versions 49a5faaa471ddcd37b6893970c9916eb836e7c31, 91359966e247c0244c66d50bbb8e74aefa4321c3, 410351158dfef2d67fea6603680b3a6013c6ed9d as the first without the flaw, so updating Linux to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.51% chance of exploitation within 30 days, which is low compared with other CVEs.

Patch this week

Critical severity: a successful attack would have severe impact.

What to do

  1. Update Linux to 49a5faaa471ddcd37b6893970c9916eb836e7c31 or 91359966e247c0244c66d50bbb8e74aefa4321c3 or 410351158dfef2d67fea6603680b3a6013c6ed9d or acdc12b71c9aa4be5dcd2c8062753c6d2033e235, whichever matches your release line, or a later version.
  2. Update Linux Kernel to 5.5 or 5.10.258 or 5.15.209 or 6.1.175, whichever matches your release line, or a later version.
  3. Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.

Affected products and versions

VendorProductAffected versionsFixed in
LinuxLinux9aaaa56845a06aeabdd597cbe19492dc01f281ec up to, but not including, 49a5faaa471ddcd37b6893970c9916eb836e7c31; 9aaaa56845a06aeabdd597cbe19492dc01f281ec up to, but not including, 91359966e247c0244c66d50bbb8e74aefa4321c3; 9aaaa56845a06aeabdd597cbe19492dc01f281ec up to, but not including, 410351158dfef2d67fea6603680b3a6013c6ed9d; 9aaaa56845a06aeabdd597cbe19492dc01f281ec up to, but not including, acdc12b71c9aa4be5dcd2c8062753c6d2033e235; 9aaaa56845a06aeabdd597cbe19492dc01f281ec up to, but not including, 929b1548e63ac72e104c07d8ee8cbbeeba2fa89a; 9aaaa56845a06aeabdd597cbe19492dc01f281ec up to, but not including, af855f4c966afafef74faf8390c7b86568c0d46d; 9aaaa56845a06aeabdd597cbe19492dc01f281ec up to, but not including, b9c015ef1a7bf1e8dc67f21c6381f36deb2c3a36; 9aaaa56845a06aeabdd597cbe19492dc01f281ec up to, but not including, ff26a0e8377dec07e4a7230db7675bed1b9a6d03; and 3 more ranges49a5faaa471ddcd37b6893970c9916eb836e7c31, 91359966e247c0244c66d50bbb8e74aefa4321c3, 410351158dfef2d67fea6603680b3a6013c6ed9d, acdc12b71c9aa4be5dcd2c8062753c6d2033e235, 929b1548e63ac72e104c07d8ee8cbbeeba2fa89a, af855f4c966afafef74faf8390c7b86568c0d46d
LinuxLinux Kernel5.4.14 up to, but not including, 5.5; 5.5.1 up to, but not including, 5.10.258; 5.11 up to, but not including, 5.15.209; 5.16 up to, but not including, 6.1.175; 6.2 up to, but not including, 6.6.142; 6.7 up to, but not including, 6.12.92; 6.13 up to, but not including, 6.18.34; 6.19 up to, but not including, 7.0.11; and 2 more ranges5.5, 5.10.258, 5.15.209, 6.1.175, 6.6.142, 6.12.92

Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.

How the severity score breaks down

Attack vector
NetworkCan be exploited remotely over a network, including the internet.
Attack complexity
LowNo special conditions are needed; the attack works reliably.
Privileges required
NoneNo account or login is needed.
User interaction
NoneNo action by a victim is required.
Scope
UnchangedImpact stays within the vulnerable component.
Confidentiality
HighAll data handled by the component can be read.
Integrity
HighData or code can be modified at will.
Availability
HighThe component can be taken down completely.

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H. Scored by CNA.

Official 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.

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: Improper Input Validation

The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.

How developers prevent this class of flaw

  • Consider using language-theoretic security (LangSec) techniques that characterize inputs using a formal language and build recognizers for that language. This effectively requires parsing to be a distinct layer that effectively enforces a boundary between raw input and internal data representations, instead of allowing parser code to be scattered throughout the program, where it could be subject to errors or inconsistencies that create weaknesses.
  • Use an input validation framework such as Struts or the OWASP ESAPI Validation API. Note that using a framework does not automatically address all input validation problems; be mindful of weaknesses that could arise from misusing the framework itself (CWE-1173).
  • Understand all the potential areas where untrusted inputs can enter the product, including but not limited to: parameters or arguments, cookies, anything read from the network, environment variables, reverse DNS lookups, query results, request headers, URL components, e-mail, files, filenames, databases, and any external systems that provide data to the application. Remember that such inputs may be obtained indirectly through API calls.

More Improper Input Validation vulnerabilities (CWE-20)

Timeline

  1. CVE record published.
  2. CISA published its SSVC assessment (exploitation: none, automatable: yes, technical impact: total).
  3. Record last changed materially (score, affected products, status or references).

References

Recent Improper Input Validation vulnerabilities

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