CVE-2026-89775: KVM: arm64: Handle negative S1 walk levels in VNCR TLB size evaluation
- Is it exploited?
Not on CISA's list. CISA has not added it to the Known Exploited Vulnerabilities catalog as of . If CISA adds it, this page shows it as known exploited.
- How likely is exploitation in the next 30 days?
- 0.2%
EPSS score, percentile 14.6 of all scored records. A probability estimated by FIRST, not a report of exploitation.
- How severe?
- 9.3 Critical
CVSS v3.1 base score, given by the CNA
- What should I do?
CISA has set no required action, because the vulnerability is not in KEV.
The CVE record links no vendor advisory, patch or mitigation.
- Which versions are affected?
Affected
- 6.16
Unaffected before 6.16; 6.18.51; 7.2.5; 7.3
Source: CISA KEV 2026.10.29, as of ; FIRST EPSS, as of ; CVE List, as of . About the data.
What to do
Advisories and patches
The CVE record links no vendor advisory, patch or mitigation.
This summary is based on the CVE record as of . Check the vendor's advisory before you act: affected versions and fixes can change.
Affected products and versions
As listed in the CVE record.
| Status | Versions |
|---|---|
| Affected | from 7270cc9157f4 to before be54a70067c7 |
| Affected | from 7270cc9157f4 to before 1c9fca34b962 |
| Affected | from 7270cc9157f4 to before 8053393680d4 |
Versions not listed are: unaffected.
| Status | Versions |
|---|---|
| Affected | 6.16 |
| Unaffected | before 6.16 |
| Unaffected | 6.18.51 |
| Unaffected | 7.2.5 |
| Unaffected | 7.3 |
Versions not listed are: affected.
Versions the record lists as unaffected: 6.18.51, 7.2.5, 7.3.
Source: CVE List, as of . About the data.
About this vulnerability
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…
Summary: CVE record, as of .
- CISA has not added CVE-2026-89775 to its Known Exploited Vulnerabilities (KEV) catalog, as of 29 Oct 2026.
- The CVE record was published on 16 Sep 2026.
- The CVE record carries a CVSS v3.1 base score of 9.3 (Critical), given by its CNA.
- FIRST's EPSS model puts the probability of exploitation in the next 30 days at 0.2% (percentile 14.6), as of 29 Oct 2026. EPSS is a statistical estimate, not a report of exploitation.
Source: CISA KEV 2026.10.29, as of ; CVE List, as of ; FIRST EPSS, as of . About the data.
Description
KVM: arm64: Handle negative S1 walk levels in VNCR TLB size evaluation
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: CVE List, as of . About the data.
Timeline
| Date | Event |
|---|---|
| CVE record published | |
| CVE record last updated |
References
3
Known exploited Linux vulnerabilities
- CVE-2026-46300: Linux Kernel Missing Initialization of a Variable Vulnerability
- CVE-2025-39682: Linux Kernel Improper Check for Unusual or Exceptional Conditions Vulnerability
- CVE-2025-39964: Linux Kernel Race Condition Vulnerability
- CVE-2026-53266: Linux Kernel Out-of-Bounds Write Vulnerability
- CVE-2026-53362: Linux Kernel Unspecified Vulnerability