CVE-2026-43331

Description

In the Linux kernel, the following vulnerability has been resolved: x86/kexec: Disable KCOV instrumentation after load_segments() The load_segments() function changes segment registers, invalidating GS base (which KCOV relies on for per-cpu data). When CONFIG_KCOV is enabled, any subsequent instrumented C code call (e.g. native_gdt_invalidate()) begins crashing the kernel in an endless loop. To reproduce the problem, it's sufficient to do kexec on a KCOV-instrumented kernel: $ kexec -l /boot/otherKernel $ kexec -e The real-world context for this problem is enabling crash dump collection in syzkaller. For this, the tool loads a panic kernel before fuzzing and then calls makedumpfile after the panic. This workflow requires both CONFIG_KEXEC and CONFIG_KCOV to be enabled simultaneously. Adding safeguards directly to the KCOV fast-path (__sanitizer_cov_trace_pc()) is also undesirable as it would introduce an extra performance overhead. Disabling instrumentation for the individual functions would be too fragile, so disable KCOV instrumentation for the entire machine_kexec_64.c and physaddr.c. If coverage-guided fuzzing ever needs these components in the future, other approaches should be considered. The problem is not relevant for 32 bit kernels as CONFIG_KCOV is not supported there. [ bp: Space out comment for better readability. ]

Gravité et risque d'exploitation

CVE-2026-43331 obtient un score CVSS de 0.0/10, soit une gravité non évaluée. Selon le modèle EPSS, la probabilité qu'elle soit exploitée dans les 30 prochains jours est de 0.12 %, ce qui la place devant 1.8 % des CVE référencées.

Que faire ?

• Vérifiez si Linux (versions <=6.12.*, <de05c66fab8847237a9ca216934e56d3ee837f08, 6.12.93, 0, 7.0, 0d345996e4cb573f8cc81d49b3ee9a7fd2035bef, <593d67032544b9271094fc9b43e437e017cb2b2f, <6.6, <=6.6.*, <=6.19.*, <1e3e98596c2769721ade0418434852fb3af4849a, 6.6, <=6.18.*, <0e96cd314c0d819c1635d68125a4d77852c2162e, <917e3ad3321e75ca0223d5ccf26ceda116aa51e1, <=*, 6.6.143, 6.18.22, 6.19.12) est présent sur votre parc.
• Appliquez le correctif ou la version corrigée indiqués dans les références de l'éditeur.
• À défaut de correctif, limitez l'exposition (filtrage réseau, désactivation du composant).
• Automatisez la détection : les agents CVE Heimdall (gratuits, open source) corrèlent l'inventaire de vos serveurs avec la base CVE.

Références

• https://git.kernel.org/stable/c/0e96cd314c0d819c1635d68125a4d77852c2162e
• https://git.kernel.org/stable/c/593d67032544b9271094fc9b43e437e017cb2b2f
• https://git.kernel.org/stable/c/1e3e98596c2769721ade0418434852fb3af4849a
• https://git.kernel.org/stable/c/de05c66fab8847237a9ca216934e56d3ee837f08
• https://git.kernel.org/stable/c/917e3ad3321e75ca0223d5ccf26ceda116aa51e1