CVE-2025-68259

Description

In the Linux kernel, the following vulnerability has been resolved: KVM: SVM: Don't skip unrelated instruction if INT3/INTO is replaced When re-injecting a soft interrupt from an INT3, INT0, or (select) INTn instruction, discard the exception and retry the instruction if the code stream is changed (e.g. by a different vCPU) between when the CPU executes the instruction and when KVM decodes the instruction to get the next RIP. As effectively predicted by commit 6ef88d6e36c2 ("KVM: SVM: Re-inject INT3/INTO instead of retrying the instruction"), failure to verify that the correct INTn instruction was decoded can effectively clobber guest state due to decoding the wrong instruction and thus specifying the wrong next RIP. The bug most often manifests as "Oops: int3" panics on static branch checks in Linux guests. Enabling or disabling a static branch in Linux uses the kernel's "text poke" code patching mechanism. To modify code while other CPUs may be executing that code, Linux (temporarily) replaces the first byte of the original instruction with an int3 (opcode 0xcc), then patches in the new code stream except for the first byte, and finally replaces the int3 with the first byte of the new code stream. If a CPU hits the int3, i.e. executes the code while it's being modified, then the guest kernel must look up the RIP to determine how to handle the #BP, e.g. by emulating the new instruction. If the RIP is incorrect, then this lookup fails and the guest kernel panics. The bug reproduces almost instantly by hacking the guest kernel to repeatedly check a static branch[1] while running a drgn script[2] on the host to constantly swap out the memory containing the guest's TSS. [1]: https://gist.github.com/osandov/44d17c51c28c0ac998ea0334edf90b5a [2]: https://gist.github.com/osandov/10e45e45afa29b11e0c7209247afc00b

Gravité et risque d'exploitation

CVE-2025-68259 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 0.19 %, ce qui la place devant 8.3 % des CVE référencées.

Que faire ?

• Vérifiez si Linux (versions <=6.1.*, <=6.12.*, 6.18.1, 6.1.160, 0, 6ef88d6e36c2b4b3886ec9967cafabe4424d27d5, 6.6.120, <54bcccc2c7805a00af1d7d2faffd6f424c0133aa, <53903ac9ca1abffa27327e85075ec496fa55ccf3, 6.17.12, <=6.6.*, 6.0, <6.0, <=6.18.*, <152289a51107ef45bbfe9b4aeeaa584a503042b5, 6.12.62, <87cc1622c88a4888959d64fa1fc9ba1e264aa3d4, <=*, <=6.17.*, 6.19, <2e84a018c2895c05abe213eb10db128aa45f6ec6, <4da3768e1820cf15cced390242d8789aed34f54d) 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/2e84a018c2895c05abe213eb10db128aa45f6ec6
• https://git.kernel.org/stable/c/152289a51107ef45bbfe9b4aeeaa584a503042b5
• https://git.kernel.org/stable/c/87cc1622c88a4888959d64fa1fc9ba1e264aa3d4
• https://git.kernel.org/stable/c/54bcccc2c7805a00af1d7d2faffd6f424c0133aa
• https://git.kernel.org/stable/c/53903ac9ca1abffa27327e85075ec496fa55ccf3
• https://git.kernel.org/stable/c/4da3768e1820cf15cced390242d8789aed34f54d