FlashAttention Symlink Attack via tarfile.extractall in hopper/setup.py (CVE-2026-62239) | HOL Guard CVE

Medium · CVSS 6.6CVE-2026-62239

FlashAttention Symlink Attack via tarfile.extractall in hopper/setup.py

Answer in brief

CVE-2026-62239 records a Medium severity (CVSS 6.6) vulnerability in FlashAttention Symlink Attack via tarfile.extractall in hopper/setup.py. The current sources do not mark it as known exploited. The current feed maps Dao-AILab/flash-attention (generic). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Jul 13, 2026Updated Sep 17, 2026Source checked Sep 17, 2026First seen by HOL Jul 13, 2026Material review Sep 17, 2026

Upstream Advisory

Key facts

Risk: Medium · CVSS 6.6
Exploitation: Not marked as known exploited
Affected software: 1 mapped package or product
Fix availability: Not reported

Why this deserves its current priority

CVSS is 6.6. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps Dao-AILab/flash-attention (generic). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
Dao-AILab/flash-attentiongeneric	0	Not reported

Recommended response

Check inventory. Check lockfiles and deployed manifests for Dao-AILab/flash-attention.
Review the reported fix. Monitor this advisory for an available fix and review any installs of the affected package.

Evidence timeline and material changes

Published upstream
Jul 13, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Sep 17, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Jul 13, 2026

Sources and claim methodology

Upstream source 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.

Quoted source text, attributed separately from HOL analysis.