CVE-2026-62239 FlashAttention Symlink Attack via tarfile.extractall in hopper/setup.py
A local attacker can exploit symlink handling in FlashAttention's build script to write arbitrary files, potentially leading to code execution or privilege escalation.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- A user has to click or open something
- Fix
- None listed
What is CVE-2026-62239?
CVE-2026-62239 is a medium-severity path traversal vulnerability in Dao-AILab flash-attention, published on 13 Jul 2026. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.
Official description
FlashAttention through 2.8.3.post1, fixed in commit 0816ef1, contains a symlink attack vulnerability in the download_and_copy() function within hopper/setup.py that extracts NVIDIA toolchain archives without validating symlinks or filtering tar members. A local attacker can pre-plant a symlink in the predictable cache directory to redirect extracted binaries to an attacker-chosen location, enabling arbitrary file write with victim privileges during build time.
Weakness: CWE-59
Which versions are affected by CVE-2026-62239?
How do I fix CVE-2026-62239?
No fix has been published for CVE-2026-62239 yet. Limit exposure of the affected software until one is available.
Upgrade, and resolve every user-supplied path against an allowed base folder before opening it. More about Path traversal.
Is CVE-2026-62239 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-62239 exists.
Sources
Also known as GHSA-w9r7-4gwr-j959.