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VulnerabilityPublished Updated

CVE-2026-64027: Linux kernel · net: shaper: rework the VALID marking

Affects Linux kernelSource CVE Database V5

0

Not known to be exploited · CVSS 7.8 High · fixed in b8d7519352ba8c6df83259295d4a3bad093cae90 : patch Linux kernel soon.

Data as of 26 Oct 2026, 17:30 UTC

CVSS 3.1 base score
7.8High
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.1% chance of exploitation in 30 days – higher than 2% 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 cannot 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 b8d7519352ba8c6df83259295d4a3bad093cae90, 2417df5e7bb4184b9d3a2988036bf2c46e594545, 96ea960dd40fd55302e0fd755176f26a95e6a50c
CVSS:3.1/AV:L/AC:L/PR:L/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 Linux kernel to b8d7519352ba8c6df83259295d4a3bad093cae90, 2417df5e7bb4184b9d3a2988036bf2c46e594545 or 96ea960dd40fd55302e0fd755176f26a95e6a50c.

Affected software

ProductAffectedFixed in
LinuxLinuxAffected
  • ≥ 93954b40f6a4fc43226c01a15b02732f884500f1, < b8d7519352ba8c6df83259295d4a3bad093cae90
Fixed in
  • b8d7519352ba8c6df83259295d4a3bad093cae90
LinuxLinuxAffected
  • ≥ 93954b40f6a4fc43226c01a15b02732f884500f1, < 2417df5e7bb4184b9d3a2988036bf2c46e594545
Fixed in
  • 2417df5e7bb4184b9d3a2988036bf2c46e594545
LinuxLinuxAffected
  • ≥ 93954b40f6a4fc43226c01a15b02732f884500f1, < 96ea960dd40fd55302e0fd755176f26a95e6a50c
Fixed in
  • 96ea960dd40fd55302e0fd755176f26a95e6a50c
LinuxLinuxAffected
  • =6.13
Fixed in–

Description

In the Linux kernel, the following vulnerability has been resolved: net: shaper: rework the VALID marking (again) Recent commit changed the semantics from NOT_VALID to VALID. I didn't realize that the flags are not stored atomically with the entry in XArray. There's still a race of reader observing a VALID mark for a slot, getting interrupted, writer replacing the entry with a different one, reader continuing, fetching the entry which is now a different pointer than the pointer for which VALID was meant. The biggest consequence of this is that we may see a UAF since net_shaper_rollback() assumed that entries without VALID can be freed without observing RCU. Looks like the XArray marks are buying us nothing at this point. Let's convert the code to an explicit valid field. The smp_load_acquire() / smp_store_release() barriers are marginally cleaner.

References

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