CVE-2026-64368: Linux Vulnerability (CVSS 8.1)

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.

Metrics

CVSS 3.1

8.1/10

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS Probability

0.42%

34.5th percentile

Probability of exploitation in the next 30 days. Learn more

Affected Software

Source: CNA advisory (CVE.org). NVD analysis pending.

Vendor	Product	Versions
Linux	Linux	>= 9ce67395f5a0cdec6ce152d26bfda13b98b25c01, < 6256899c3a34674bba6076884aedbba49fc695e4; >= 9ce67395f5a0cdec6ce152d26bfda13b98b25c01, < 7e706d50fa119eead6376bf0ef973e8d73a96030; >= 9ce67395f5a0cdec6ce152d26bfda13b98b25c01, < 2382971aaaef5bf85a651234c64906f59580b8be; >= 9ce67395f5a0cdec6ce152d26bfda13b98b25c01, < 0d18ccef142f04433dfb2a0c120cf223d2b8a42c; >= 9ce67395f5a0cdec6ce152d26bfda13b98b25c01, < 648927ceb84021a25a0fbd5673740956f318d534
Linux	Linux	6.2

References

Timeline

Published: Jul 25, 2026
Last Modified: Aug 11, 2026
Status: Awaiting Analysis

Frequently Asked Questions

What is CVE-2026-64368?

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.

How severe is CVE-2026-64368?

CVE-2026-64368 has a CVSS score of 8.1/10 (HIGH severity). The EPSS model estimates a 0.42% probability of exploitation in the next 30 days.

How do I fix CVE-2026-64368?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

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