Researchers Demonstrate OpenBSD Root Exploit Chaining 37-Year-Old Shared-Memory Bug
A local privilege escalation exploit published today gains root on OpenBSD 7.9 by chaining a roughly 37-year-old integer overflow with a separate kernel flaw, bypassing OpenBSD's KARL kernel-address randomization and its SMAP and SMEP hardware protections. Security firm Calif, which found and reported the flaws, published a detailed writeup and full proof-of-concept code after OpenBSD shipped patches for both issues in September. The integer overflow in the shmat(4) attach function was fixed in errata 018 , shipped September 14 as a reliability fix. The reference-counting use-after-free that completes the chain was fixed separately in errata 026, shipped September 30 as a security fix. Both are available through syspatch and cover all architectures. OpenBSD 7.8 also received the integer-overflow fix. The integer overflow, the entry point for the full chain, is classified as a reliability fix, not a security fix. No CVE has been assigned for either flaw as of publication...
Oct 16, 2026