PYSEC-2026-2874
Pillow has a PDF Parsing Trailer Infinite Loop (DoS)
At a glance
- Published
- Updated
- CVE
- CVE-2026-42310
- Aliases
- BIT-pillow-2026-42310, GHSA-r73j-pqj5-w3x7
- CVSS_V3
- CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
- CVSS_V4
- CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N
Description
### Impact An attacker can supply a malicious PDF that causes the process to hang indefinitely, consuming 100% CPU and making the application unresponsive. ### Patches Patched version: 12.2.0. PdfParser (introduced in Pillow 4.2.0) follows Prev pointers in PDF trailers to read cross-reference sections. If a trailer's Prev pointer references an offset that has already been processed — either pointing to itself or forming a longer cycle — the parser enters an infinite loop. Pillow now tracks previously processed trailer offsets and raises an error if a cycle is detected. ### Workarounds Use any version but the affected versions: >= 4.2.0, < 12.2.0 ### Resources - Fix: https://github.com/python-pillow/Pillow/pull/9519
Affected packages
| Package | Versions |
|---|---|
| PyPI · pillow | introduced 4.2.0, fixed 12.2.0 |
References
- https://github.com/python-pillow/Pillow/security/advisories/GHSA-r73j-pqj5-w3x7 WEB
- https://nvd.nist.gov/vuln/detail/CVE-2026-42310 ADVISORY
- https://github.com/python-pillow/Pillow/pull/9519 WEB
- https://github.com/python-pillow/Pillow/commit/3bf614e4b8615d0ce1d5039efaf6db447fe7c468 WEB
- https://github.com/python-pillow/Pillow PACKAGE
- https://github.com/python-pillow/Pillow/releases/tag/12.2.0 WEB
- https://pypi.org/project/pillow PACKAGE
- https://github.com/advisories/GHSA-r73j-pqj5-w3x7 ADVISORY
Sources
| Source | Licence |
|---|---|
| OSV.dev | CC-BY 4.0 — PyPA Advisory Database |