Researcher weaponizes libheif 1-day into full RCE via UAF and tcache poisoning

dyn___ · x · 2026-09-23

After Hacktron's libheif-based pwn of OpenAI, researcher kmkzsecurity found an undocumented remote primitive in libheif 1.23.x behind an image API: attacker-controlled iref/dimg reference graphs produce repeatable malloc(16) allocations in glibc's 0x20 class, enabling remote heap grooming.

When a fresh libheif 1-day with no public PoC dropped, he built a full chain from the source diff: TAI use-after-free → reclaim → stale free → safe-linked tcache poison → ZdlPvm GOT hijack → system() → RCE.

The underlying bug is GHSA-qwpf-5wf7-r996: a shallow-copied mtaitimestamp raw pointer causes use-after-free and double free, affecting libheif 1.21.0–1.23.4, patched in 1.23.5, found by Tencent's Yunding Lab. No PoC was published.

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