CVE-2026-62239
FlashAttention Symlink Attack via tarfile.extractall in hopper/setup.py
- State
- Published
- Severity
- 5.3 Medium
- Published
- Jul 13, 2026
- Updated
- Sep 17, 2026
- Reserved
- Jul 13, 2026
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.
Scores
| CVSS | Score | Vector | Source |
|---|---|---|---|
| 4.0 | 5.3 Medium | CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:P/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N | VulnCheck |
| 3.1 | 6.6 Medium | CVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:N | VulnCheck |
Weaknesses
- CWE-59 Improper Link Resolution Before File Access ('Link Following')
Affected Products
| Product | Versions |
|---|---|
flash-attentionDao-AILab |
|
References
- Researcher Disclosuretechnical-descriptionexploitissue-tracking
- Pull Requestissue-trackingpatch
- Patch Commitpatch
- https://www.vulncheck.com/advisories/flashattention-symlink-attack-via-tarfile-extractall-in-hopper-setup-pythird-party-advisory
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