Bug 2464487 (CVE-2026-43043)

Summary: CVE-2026-43043 kernel: crypto: af-alg - fix NULL pointer dereference in scatterwalk
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
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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 af-alg subsystem. When the AF_ALG interface chains a new af_alg_tsgl structure, it fails to unmark the end of a Scatter/Gather List (SGL). This can lead to a NULL pointer dereference during a subsequent sendmsg() operation, causing a kernel panic and resulting in a Denial of Service (DoS).
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Description OSIDB Bzimport 2026-05-01 15:09:33 UTC 
In the Linux kernel, the following vulnerability has been resolved:

crypto: af-alg - fix NULL pointer dereference in scatterwalk

The AF_ALG interface fails to unmark the end of a Scatter/Gather List (SGL)
when chaining a new af_alg_tsgl structure. If a sendmsg() fills an SGL
exactly to MAX_SGL_ENTS, the last entry is marked as the end. A subsequent
sendmsg() allocates a new SGL and chains it, but fails to clear the end
marker on the previous SGL's last data entry.

This causes the crypto scatterwalk to hit a premature end, returning NULL
on sg_next() and leading to a kernel panic during dereference.

Fix this by explicitly unmarking the end of the previous SGL when
performing sg_chain() in af_alg_alloc_tsgl().
Comment 1 Keith Grant 2026-05-01 18:12:28 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026050104-CVE-2026-43043-6997@gregkh/T