Vulnerability in FreeBSD

[ Description ]Official 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.

[ Fixes ]Fixes and patches

No fix or interim patch is linked from our sources yet. Check the vendor references below and limit exposure of affected systems until a fix is available.

[ Advisories ]Government CERT advisories

• BSI CERT-Bund29 Sep 2026WID-SEC-2026-3664

  FreeBSD Project FreeBSD OS: Multiple vulnerabilities Translated from German

  CVE-2026-84783CVE-2026-101305CVE-2026-101306+7 more CVEs

[ References ]References

• security.freebsd.org/advisories/FreeBSD-SA-26:64.sysvsem.ascVendor Advisory