Home

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.

PUBLISHED Reserved 2026-07-13 | Published 2026-07-13 | Updated 2026-07-14 | Assigner VulnCheck




MEDIUM: 5.3CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:P/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N

MEDIUM: 6.6CVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:N

Problem types

Improper Link Resolution Before File Access ('Link Following')

Product status

Default status
unaffected

Any version
affected

0816ef12f424c6ec94b057a72c275b14f6e6edb2 (git)
unaffected

Credits

YU SUN finder

References

github.com/Dao-AILab/flash-attention/issues/2637 exploit

github.com/Dao-AILab/flash-attention/issues/2637 (Researcher Disclosure) technical-description exploit issue-tracking

github.com/Dao-AILab/flash-attention/pull/2702 (Pull Request) issue-tracking patch

github.com/...ommit/0816ef12f424c6ec94b057a72c275b14f6e6edb2 (Patch Commit) patch

www.vulncheck.com/...a-tarfile-extractall-in-hopper-setup-py third-party-advisory

cve.org (CVE-2026-62239)

nvd.nist.gov (CVE-2026-62239)

Download JSON