CVE-2026-89775KVM: arm64: Handle negative S1 walk levels in VNCR TLB size evaluation
- 9.3CriticalCVSS base score
- 0.24%Exploitation in 30 daysEPSS · top 85% of all CVEs
- NoKnown exploitednot in CISA's KEV catalog
- NonePublic exploitsnone known yet
Description
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.
Timeline
ID reserved
By Linux
- 5 days later
· 5 days later
Published
- 33 days later
· 33 days later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| LinuxCNA (assigner) | 3.1 | Critical9.3 | CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H |
| NVDNVD · Received | 3.1 | Critical9.3 | CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H |
- EPSS (exploitation in 30 days)
- 0.24% · top 85% of all CVEs (14 Nov 2026)
The list uses the assigner's score when there is one, then CISA's, then NVD's: Critical 9.3.
Affected products
- affected 7270cc9157f474dfc46750a34c9d7defc686b2eb – < be54a70067c7dbe1381157e8a238fa4b16ea9c05
- affected 7270cc9157f474dfc46750a34c9d7defc686b2eb – < 1c9fca34b9625a67a7f1a03c8604f3df760c6c49
- affected 7270cc9157f474dfc46750a34c9d7defc686b2eb – < 8053393680d4fa3eb962667d2be95dd39f0940e5
- affected 6.16
- unaffected < 6.16
- unaffected 6.18.51 – ≤ 6.18.*
- unaffected 7.2.5 – ≤ 7.2.*
- unaffected 7.3 – ≤ *
References
References4
- https://git.kernel.org/stable/c/be54a70067c7dbe1381157e8a238fa4b16ea9c05 (opens in a new tab)
- https://git.kernel.org/stable/c/1c9fca34b9625a67a7f1a03c8604f3df760c6c49 (opens in a new tab)
- https://git.kernel.org/stable/c/8053393680d4fa3eb962667d2be95dd39f0940e5 (opens in a new tab)
- http://www.openwall.com/lists/oss-security/2026/09/16/14 (opens in a new tab)
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- EUVD EUVD-2026-80296 (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://cveledger.app/cve/CVE-2026-89775)Record last updated .