CVE-2026-89775

CVE CVE-2026-89775EUVD EUVD-2026-80296Published 2026-09-16T08:39:16.000ZLast changed 2026-09-16T17:07:09.000ZCVSS 9.3

What the advisory describes

In the Linux kernel, the following vulnerability has been resolved: KVM: arm64: Handle negative S1 walk levels in VNCR TLB size evaluation Computing the effects of a TLB invalidation involves looking at the size of the mapping cached by the TLB. For S1 mappings such as VNCR, this is deducted from the combination of the base granule size and the mapping level. However, this implies that the S1 MMU is *on*. When the MMU is off, we indicate this with the level being set to a "creative" value of -127 (S1_MMU_DISABLED). This ends-up being misinterpreted by pgshift_level_to_ttl() as it doesn't handle negative levels at all (the level is immediately cast to a u8 and only the bottom two bits considered), leading to an invalidation size of 0. Not helpful. Tidy-up pgshift_level_to_ttl() to handle these negative levels, and ttl_to_size() to always return SZ_1G when no valid TTL is present. This allows the removal of open-coded checks for similar situations. Note that the check for a negative value not explicitely checking for S1_MMU_DISABLED is deliberate, so that actual negative levels introduced with LVA2 and D128 can take the same path if we ever support them.

Source: EUVD (ENISA), in the words of the advisory.

Products the advisory names

These come from the advisory itself, not from any check we performed.

• Linux — Linux patch: 6.18.51; 7270cc9157f474dfc46750a34c9d7defc686b2eb <be54a70067c7dbe1381157e8a238fa4b16ea9c05; patch: 7.3-rc1; patch: 7.2.5; patch: 0; 6.16; 7270cc9157f474dfc46750a34c9d7defc686b2eb <1c9fca34b9625a67a7f1a03c8604f3df760c6c49; 7270cc9157f474dfc46750a34c9d7defc686b2eb <8053393680d4fa3eb962667d2be95dd39f0940e5

The versions shown are the advisory's own. Patchlage compares no version numbers and derives no judgement from them — which version is installed is something a person has to look up.

Carried in the product catalogue

An estate covering these products can be recorded in Patchlage. An advisory about them appears in the next morning's situation report.

• Linux — Linux

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