CVE-2026-6386: Missing large page handling in pmap_pkru_update_range()
- 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 10.4 of all scored records. A probability estimated by FIRST, not a report of exploitation.
- How severe?
- 6.2 Medium
CVSS v3.1 base score, from CISA's enrichment of the record
- What should I do?
CISA has set no required action, because the vulnerability is not in KEV.
- Which versions are affected?
Affected
- from 15.0-RELEASE to before p6
- from 14.4-RELEASE to before p2
- from 14.3-RELEASE to before p11
- from 13.5-RELEASE to before p12
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
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 15.0-RELEASE to before p6 |
| Affected | from 14.4-RELEASE to before p2 |
| Affected | from 14.3-RELEASE to before p11 |
| Affected | from 13.5-RELEASE to before p12 |
Versions not listed are: unknown.
Source: CVE List, as of . About the data.
About this vulnerability
In order to apply a particular protection key to an address range, the kernel must update the corresponding page table entries. The subroutine which handled this failed to take into account the presence of 1GB largepage mappings created using the shm_create_largepage(3) interface. In particular, it would always treat a page directory page entry as pointing to another page table page. The bug c…
Summary: CVE record, as of .
- CISA has not added CVE-2026-6386 to its Known Exploited Vulnerabilities (KEV) catalog, as of 29 Oct 2026.
- The CVE record was published on 22 Apr 2026.
- The CVE record carries a CVSS v3.1 base score of 6.2 (Medium), taken from CISA's enrichment of the record.
- FIRST's EPSS model puts the probability of exploitation in the next 30 days at 0.2% (percentile 10.4), as of 29 Oct 2026. EPSS is a statistical estimate, not a report of exploitation.
- CISA's SSVC assessment in the CVE record: exploitation none, automatable no, technical impact partial.
- The credits in the CVE record name Anthropic (Claude) as finder.
Source: CISA KEV 2026.10.29, as of ; CVE List, as of ; FIRST EPSS, as of . About the data.
Description
Missing large page handling in pmap_pkru_update_range()
In order to apply a particular protection key to an address range, the kernel must update the corresponding page table entries. The subroutine which handled this failed to take into account the presence of 1GB largepage mappings created using the shm_create_largepage(3) interface. In particular, it would always treat a page directory page entry as pointing to another page table page. The bug can be abused by an unprivileged user to cause pmap_pkru_update_range() to treat userspace memory as a page table page, and thus overwrite memory to which the application would otherwise not have access.
Source: CVE List, as of . About the data.
Weakness
CWE-269, CWE-732
- CWE-269: Improper Privilege Management
- CWE-732: Incorrect Permission Assignment for Critical Resource
CWE and CAPEC are maintained by MITRE; the entries are those named in the CVE record.
Timeline
| Date | Event |
|---|---|
| CVE record published |