What’s Vulnerable › Vulnerabilities

CVE-2026-62239: FlashAttention Symlink Attack via tarfile.extractall in hopper/setup.py

• Severity: medium (CVSS 6.6 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.2% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-07-13 · updated 2026-10-24
• Weakness: CWE-59

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.

Affected products

• Dao-AILab flash-attention: through 2.8.3.post1

References

• https://github.com/Dao-AILab/flash-attention/commit/0816ef12f424c6ec94b057a72c275b14f6e6edb2
• https://github.com/Dao-AILab/flash-attention/issues/2637
• https://github.com/Dao-AILab/flash-attention/pull/2702
• https://www.vulncheck.com/advisories/flashattention-symlink-attack-via-tarfile-extractall-in-hopper-setup-py
• https://github.com/Dao-AILab/flash-attention/issues/2637

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