CVE-2026-58098: freebsd Out-of-bounds Write

Vulnerability summary

CVE-2026-58098 is a high (CVSS 8.4) Out-of-bounds Write vulnerability in freebsd. EPSS estimates a 0.17% chance of exploitation in the next 30 days, higher than 5.6% of scored vulnerabilities.

Timeline

1. 15-10-2026
   PublishedVulnerability first disclosed.
2. 16-10-2026
   Last modifiedVulnerability information updated.

Description

When semop(2) blocks waiting for a semaphore condition, it releases the per-set lock and sleeps. Upon waking, it checks the sequence number embedded in the semaphore set's IPC identifier to detect whether the set was removed while the caller was asleep. This sequence number is only 15 bits wide. If enough semaphore sets are created and destroyed in the same table slot while a caller is blocked, the counter wraps around, and semop(2) may falsely conclude that the original set still exists. The subsequent access to a semaphore within the set may then be out of bounds. An unprivileged local user can trigger an out-of-bounds access on kernel heap memory, potentially leading to privilege escalation.

• CWE-787Out-of-bounds WriteThe product writes data past the end, or before the beginning, of the intended buffer.