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VulnerabilityPublished Updated

CVE-2026-64368: Linux kernel · mm/slab: do not limit zeroing to orig_size when only red zoning is enabled

Affects Linux kernelSource CVE Database V5

0

Not known to be exploited · CVSS 8.1 High · fixed in 6256899c3a34674bba6076884aedbba49fc695e4 : patch Linux kernel soon.

Data as of 26 Oct 2026, 17:30 UTC

CVSS 3.1 base score
8.1High
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.4% chance of exploitation in 30 days – higher than 35% 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 6256899c3a34674bba6076884aedbba49fc695e4, 2382971aaaef5bf85a651234c64906f59580b8be, 648927ceb84021a25a0fbd5673740956f318d534 +2
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 25 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
  • ≥ 9ce67395f5a0cdec6ce152d26bfda13b98b25c01, < 6256899c3a34674bba6076884aedbba49fc695e4
Fixed in
  • 6256899c3a34674bba6076884aedbba49fc695e4
LinuxLinuxAffected
  • ≥ 9ce67395f5a0cdec6ce152d26bfda13b98b25c01, < 2382971aaaef5bf85a651234c64906f59580b8be
Fixed in
  • 2382971aaaef5bf85a651234c64906f59580b8be
LinuxLinuxAffected
  • ≥ 9ce67395f5a0cdec6ce152d26bfda13b98b25c01, < 648927ceb84021a25a0fbd5673740956f318d534
Fixed in
  • 648927ceb84021a25a0fbd5673740956f318d534
LinuxLinuxAffected
  • ≥ 9ce67395f5a0cdec6ce152d26bfda13b98b25c01, < 7e706d50fa119eead6376bf0ef973e8d73a96030
Fixed in
  • 7e706d50fa119eead6376bf0ef973e8d73a96030
LinuxLinuxAffected
  • ≥ 9ce67395f5a0cdec6ce152d26bfda13b98b25c01, < 0d18ccef142f04433dfb2a0c120cf223d2b8a42c
Fixed in
  • 0d18ccef142f04433dfb2a0c120cf223d2b8a42c
LinuxLinuxAffected
  • =6.2
Fixed in–

Description

In the Linux kernel, the following vulnerability has been resolved: mm/slab: do not limit zeroing to orig_size when only red zoning is enabled When init (zeroing) on allocation is requested, for kmalloc() we generally have to zero the full object size even if a smaller size is requested, in order to provide krealloc()'s __GFP_ZERO guarantees. But if we track the requested size, krealloc() uses that information to do the right thing, so we can zero only the requested size. With red zoning also enabled, any extra size became part of the red zone, so it must not be zeroed and thus we must zero only the requested size. However the current check is imprecise, and will trigger also when only SLAB_RED_ZONE is enabled without SLAB_STORE_USER (which enables tracking the requested size). This means enabling red zoning alone can compromise krealloc()'s __GFP_ZERO contract. Fix this by using slub_debug_orig_size() instead, which is the exact check for whether the requested size is tracked. We don't need to care if red zoning is also enabled or not. Also update and expand the comment accordingly.

References

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