Bug 2468057 (CVE-2026-43336)

Summary: CVE-2026-43336 kernel: lib/crypto: chacha: Zeroize permuted_state before it leaves scope
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
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Version: unspecifiedCC: rhel-process-autobot, watson-tool-maintainers
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Hardware: All   
OS: Linux   
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A flaw was found in the Linux kernel's ChaCha cryptographic algorithm implementation. The `permuted_state` local variable, which is sufficient to compute the original cryptographic key, was not properly zeroized before leaving its scope. This oversight could allow an attacker to recover the cryptographic key, leading to information disclosure.
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Description OSIDB Bzimport 2026-05-08 14:02:19 UTC 
In the Linux kernel, the following vulnerability has been resolved:

lib/crypto: chacha: Zeroize permuted_state before it leaves scope

Since the ChaCha permutation is invertible, the local variable
'permuted_state' is sufficient to compute the original 'state', and thus
the key, even after the permutation has been done.

While the kernel is quite inconsistent about zeroizing secrets on the
stack (and some prominent userspace crypto libraries don't bother at all
since it's not guaranteed to work anyway), the kernel does try to do it
as a best practice, especially in cases involving the RNG.

Thus, explicitly zeroize 'permuted_state' before it goes out of scope.
Comment 1 Alexander B 2026-05-15 11:33:36 UTC 
Upstream advisory:
https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-43336.mbox