CVE-2026-58098 Heap out-of-bounds access in semop(2)
An unprivileged local user can trigger a heap out-of-bounds access in the FreeBSD kernel via semop(2), potentially leading to privilege escalation.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-58098?
CVE-2026-58098 is a high-severity memory corruption vulnerability in Freebsd Freebsd, published on 15 Oct 2026. It can only be exploited from the same machine or local network, with no action from the victim.
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.
Weakness: CWE-787
Which versions are affected by CVE-2026-58098?
It affects 1 product.
Products include Freebsd Freebsd.
How do I fix CVE-2026-58098?
No fix has been published for CVE-2026-58098 yet. Limit exposure of the affected software until one is available.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2026-58098 being exploited?
There is no known exploitation of CVE-2026-58098 in the wild and no public exploit code.