CVE-2026-62239
FlashAttention Symlink Attack via tarfile.extractall in hopper/setup.py
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.
Attack profile
How easy it is to exploit
- Attack vector
- Local
- Complexity
- Low
- Privileges needed
- Low
- User interaction
- Passive
What an attacker can affect
- Confidentiality
- High
- Integrity
- High
- Availability
- None
Exploit likelihood
What each source reports
CVE List Score used
5.3
FlashAttention Symlink Attack via tarfile.extractall in hopper/setup.py
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.
- Record
CVE-2026-62239- CVSS 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 - CVSS 3.1
- 6.6 Medium
CVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:N - Weakness
- CWE-59
- Updated
- 2026-11-02
EUVDEUVD-2026-43554
5.3
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.
- Record
EUVD-2026-43554- CVSS 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 - Updated
- 2026-11-02
GitHub AdvisoriesGHSA-w9r7-4gwr-j959
5.3
FlashAttention through 2.8.3.post1, fixed in commit 0816ef1, contains a symlink attack...
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.
- Record
GHSA-w9r7-4gwr-j959- CVSS 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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X - CVSS 3.1
- 6.6 Medium
CVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:N - Weakness
- CWE-59
- Updated
- 2026-11-02
NVD
5.3
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.
- Record
CVE-2026-62239- CVSS 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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X - CVSS 3.1
- 6.6 Medium
CVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:N - Weakness
- CWE-59
- Updated
- 2026-11-02
OSV
5.3
FlashAttention Symlink Attack via tarfile.extractall in hopper/setup.py
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.
- Record
CVE-2026-62239- CVSS 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 - Weakness
- CWE-59
- Updated
- 2026-11-02
Affected products
History
| Recorded | Changed | Sources |
|---|---|---|
| first indexed | CVE List, EUVD, GitHub Advisories, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2026-62239 is a medium vulnerability (CVSS 5.3) in Dao-ailab Flash-attention, published July 13, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.16%, the 5th percentile. No source names a fixed version.
References
github.com/Dao-AILab/flash-attention/issues/2637
github.com/Dao-AILab/flash-attention/pull/2702
github.com/Dao-AILab/flash-attention/commit/0816ef12f424c6ec94b057a72c275b14f6e6edb2
vulncheck.com/advisories/flashattention-symlink-attack-via-tarfile-extractall-in-hopper-setup-py
nvd.nist.gov/vuln/detail/CVE-2026-62239
github.com/advisories/GHSA-w9r7-4gwr-j959
github.com/CVEProject/cvelistV5/tree/main/cves/2026/62xxx/CVE-2026-62239.json
github.com/Dao-AILab/flash-attention