Vulnerability in Dao-Ailab Flash-Attention
CVE-2026-62239
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 · last modified .
CVSS v3 metric
CVSS v3 base score 6.6 (Medium). Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:N.
EPSS exploit prediction
EPSS: 0.002 (5.3th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 5th percentile — 5.3% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.002 · newest: 0.002 · change: 0.000
Affected products
- Dao-Ailab Flash-Attention — versions 0, 0816ef12f424c6ec94b057a72c275b14f6e6edb2
Weakness classification (CWE)
References
- github.com/Dao-AILab/flash-attention/issues/2637 (issue-tracking, technical-description, exploit)
- github.com/Dao-AILab/flash-attention/pull/2702 (issue-tracking, patch)
- github.com/Dao-AILab/flash-attention/commit/0816ef12f424c6ec94b057a72c275b14f6e… (patch)
- www.vulncheck.com/advisories/flashattention-symlink-attack-via-tarfile-extracta… (third-party-advisory)
Frequently asked questions
- What is CVE-2026-62239?
- CVE-2026-62239 is a medium-severity vulnerability in Dao-Ailab Flash-Attention, classified under Improper Link Resolution Before File Access. CVSS score: 6.6/10. Published 2026-07-13.
- How severe is CVE-2026-62239?
- Medium severity. CVSS v3 base score is 6.6 out of 10.