Vulnerability in Linux

[ Description ]Official description

In the Linux kernel, the following vulnerability has been resolved: KVM: arm64: Apply the fine-grained UNDEFs without FEAT_FGT FGUs don't actually require hardware support, so don't gate fgt trap config insertion on FGT. This is the only action required to allow FGUs always, as kvm_calculate_traps() already computes the FGU bits with or without FEAT_FGT. This also fixes a spurious WARN when a TLBI OS is run on a guest in vEL1 without FEAT_TLBIOS on non FEAT_FGT hardware. In this configuration the course-grained HCR_EL2.TTLBOS trap reaches the handler handle_tlbi_el1(), which expects an EL1 TLBI only from vEL2. With FGUs enabled the UNDEF will be injected without needing the specific handler. [oliver: Take Wei-Lin's suggested changelog]

[ Fixes ]Fixes and patches

No fix or interim patch is linked from our sources yet. Check the vendor references below and limit exposure of affected systems until a fix is available.

[ Advisories ]Government CERT advisories

• BSI CERT-Bund18 Oct 2026WID-SEC-2026-4019

  Linux Kernel: Multiple vulnerabilities Translated from German

  CVE-2026-98866CVE-2026-98624CVE-2026-98745+326 more CVEs

[ References ]References

• git.kernel.org/stable/c/1113374a17d7f7d16b02ee0bbd9b1e7a60cbb087
• git.kernel.org/stable/c/2f4a15c52a552c5244ec27f4ca8bda855594f918
• git.kernel.org/stable/c/4bdd2b3a708c1feb701cb8b62feb8ad2fd77bb07
• git.kernel.org/stable/c/af3300b3a6bace925a496f3520e171c07b999c72