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Link Following (Symlink)Weakness · CWE-59

CVE-2026-62239

MEDIUM · 6.6 CVSS v3.1 Published 2026-07-13
Patch available
A vendor patch is available. No clean upgrade release — apply the published patch.
See remediation →
66/100
Remediation priority · Elevated
Patch available 5 weeks old

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
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.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis
How this class of weakness works · CWE-59

A file operation follows a symbolic link without checking where it actually points, so an attacker who can plant or swap a link redirects the operation to a file they should not be able to touch. It is a common local privilege-escalation primitive. Remediation is resolving and validating the real target path, and avoiding operations on attacker-controllable links.

General guidance for the link following (symlink) class — the official description and references above are authoritative for this specific CVE. Want a bespoke review and a reviewed fix? Ask our team →

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Local
Complexity
Low
Privileges
Low
User interaction
Required
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
None

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

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Patch available Apply the vendor patch
Vendor patch github.com →
Recommended fix Moderate confidence

A version newer than 2.8.3.post1 that includes commit 0816ef12f424c6ec94b057a72c275b14f6e6edb2

  1. Clone or navigate to the flash-attention repository
  2. Verify current version is 2.8.3.post1 or earlier using: pip show flash-attention or git log --oneline
  3. Fetch the latest repository changes: git fetch origin
  4. Check available tags to identify version containing fix: git tag | grep -E '^v?[0-9]','Alternatively, directly apply the fix commit: git cherry-pick 0816ef12f424c6ec94b057a72c275b14f6e6edb2
  5. Verify the fix in hopper/setup.py ensures symlink validation is present in download_and_copy() function
  6. Rebuild and reinstall: pip install -e . or python setup.py install
  7. Clear any predictable cache directories used during build to prevent pre-planted symlink attacks

Generated from the published advisory — verify against the referenced sources before acting.

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-62239 in production — separate from our analysis above.

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