Pillow has an OOB Write with Invalid PSD Tile Extents (Integer Overflow)
### Impact Processing a malicious PSD file could lead to memory corruption, potentially resulting in a crash or arbitrary code execution. ### Patches Patched version: 12.2.0 Pillow 12.1.1 addressed CVE-2026-25990 by adding checks for tile extents in PSD image decoding/encoding to prevent an out-of-bounds write. However, the bounds checks computed tile extent sums using types susceptible to integer overflow, meaning a PSD image with carefully chosen tile dimensions could produce values that wrap around and bypass the checks, still triggering an out-of-bounds write in src/decode.c and src/encode.c. The fix avoids adding extents together before comparison. ### Workarounds Use any version but affected versions: >= 10.3.0, < 12.2.0 ### Resources - Fix: https://github.com/python-pillow/Pillow/pull/9520 - Original issue: CVE-2026-25990 (Pillow 12.1.1)
02 / AFFECTED SOFTWARE
Affected packages
9 explicit affected versions
9 explicit affected versions
8 explicit affected versions
03 / CONNECTIONS
Connected vulnerabilities
04 / EVIDENCE
Source records
Pillow is a Python imaging library. From version 10.3.0 to before version 12.2.0, processing a malicious PSD file could lead to memory corruption, potentially resulting in a crash or arbitrary code execution. This issue has been patched in version 12.2.0.
Pillow is a Python imaging library. From version 10.3.0 to before version 12.2.0, processing a malicious PSD file could lead to memory corruption, potentially resulting in a crash or arbitrary code execution. This issue has been patched in version 12.2.0.
Pillow is a Python imaging library. From version 10.3.0 to before version 12.2.0, processing a malicious PSD file could lead to memory corruption, potentially resulting in a crash or arbitrary code execution. This issue has been patched in version 12.2.0.
### Impact Processing a malicious PSD file could lead to memory corruption, potentially resulting in a crash or arbitrary code execution. ### Patches Patched version: 12.2.0 Pillow 12.1.1 addressed CVE-2026-25990 by adding checks for tile extents in PSD image decoding/encoding to prevent an out-of-bounds write. However, the bounds checks computed tile extent sums using types susceptible to integer overflow, meaning a PSD image with carefully chosen tile dimensions could produce values that wrap around and bypass the checks, still triggering an out-of-bounds write in src/decode.c and src/encode.c. The fix avoids adding extents together before comparison. ### Workarounds Use any version but affected versions: >= 10.3.0, < 12.2.0 ### Resources - Fix: https://github.com/python-pillow/Pillow/pull/9520 - Original issue: CVE-2026-25990 (Pillow 12.1.1)
05 / REFERENCES
Further evidence
- https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/42xxx/CVE-2026-42311.json
- https://github.com/python-pillow/Pillow/commit/58f9a1d166dcb0c274807d4423522d205b0c35ea
- https://github.com/python-pillow/Pillow/pull/9520
- https://github.com/python-pillow/Pillow/releases/tag/12.2.0
- https://github.com/python-pillow/Pillow/security/advisories/GHSA-pwv6-vv43-88gr
- https://nvd.nist.gov/vuln/detail/CVE-2026-42311
- https://github.com/python-pillow/Pillow
- https://github.com/python-pillow/Pillow/security/advisories/GHSA-cfh3-3jmp-rvhc