Bug 2517024 (CVE-2026-74566)

Summary: CVE-2026-74566 kernel: keys: make keyring key-chunk byte order agree with keyring_diff_objects()
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: rhel-process-autobot, watson-tool-maintainers
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in the Linux kernel's `keys` subsystem. An inconsistency in how key descriptions are processed by the `keyring_get_key_chunk()` and `keyring_diff_objects()` functions could allow a local attacker to create specially crafted key descriptions. These crafted descriptions might collide, potentially leading to unexpected system behavior or a denial of service.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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Description OSIDB Bzimport 2026-08-15 12:45:09 UTC
In the Linux kernel, the following vulnerability has been resolved:

keys: make keyring key-chunk byte order agree with keyring_diff_objects()

keyring_get_key_chunk() loads description bytes into the index chunk low
address first, while keyring_diff_objects() numbers the first differing
bit from the low end and folds the absolute byte index into the level
without removing the inline-prefix offset the level already carries.
The two disagree on byte order and bit position, so the array can be
told two keys first differ at a bit that does not differ in the chunk
the walker uses, letting crafted descriptions collide into one node.

Load the chunk in the order keyring_diff_objects() assumes and drop the
inline-prefix length when folding the byte index into the level.  This
only changes the in-memory ordering used to place keys within a keyring;
add, search and read of non-colliding keys are unaffected.

Comment 1 Mauro Matteo Cascella 2026-08-21 07:46:00 UTC
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026081553-CVE-2026-74566-8e78@gregkh/T