CVE-2026-6386: medium-severity vulnerability in FreeBSD
Missing large page handling in pmap_pkru_update_range()
Published
13Vexday Risk Score
No sign of exploitation. No public exploitation artifact known so far.
ssvc Trackcvss 6.2epss 0.2%
exploitation probability
0.2%top 95% of all CVEs
observed exploitation
nono source reports it
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.
CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
Affected products
FreeBSD · FreeBSDRelated CVEs — FreeBSD
In the same product, most dangerous first.