pypdf: Possible infinite loop when processing threads/articles in writer
Priority LOW 30CWE-835Published · Updated
Key facts
- Attack vector
- Local
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Attack requirements
- None
- Impact type
- Denial of service
- Confidentiality · integrity · availability
- None · None · High
- Fix status
- Partial Red Hat: 6 without a fix
Attack profile from CVSS 4.0 · CNA. Fix status from CNA, GitHub and Red Hat. Impact type from CWE-835.
Summary
pypdf is a free and open-source pure-python PDF library. Prior to 6.13.1, an attacker who uses this vulnerability can craft a PDF which leads to an infinite loop. This requires merging a file with threads/articles into a writer. This vulnerability is fixed in 6.13.1.
Why it matters now
Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00158 5th percentileScored 2026-11-07
Fix Partial pypdf (py-pdf): 6.13.1pypdf (PyPI): 6.13.1Red Hat: 6 without a fix
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- No
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| py-pdf | pypdf | before 6.13.1 | 6.13.1 | Patch available | CNA |
| — | pypdf (PyPI) | before 6.13.1 | 6.13.1 | Patch available | GHSA-g9xf-7f8q-9mcj |
- pypdf Vendorpy-pdf Affected before 6.13.1 Fixed in 6.13.1 Patch available CNA
- pypdf (PyPI) Vendor— Affected before 6.13.1 Fixed in 6.13.1 Patch available GHSA-g9xf-7f8q-9mcj
Remediation
- Fix · CNA pypdf (py-pdf) Fixed in 6.13.1
- Fix · GHSA-g9xf-7f8q-9mcj pypdf (PyPI) Fixed in 6.13.1 Advisory →
Vendor assessments
Red Hat
Red Hat rating: Moderate. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| Exploit Intelligence | Affected | No fix yet: Fix deferred |
| OpenShift Lightspeed | Affected | No fix yet: Fix deferred |
| Red Hat Ansible Automation Platform 2 | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux AI (RHEL AI) 3 | Affected | No fix yet: Fix deferred |
| Red Hat OpenShift AI (RHOAI) | Affected | No fix yet: Fix deferred |
| Red Hat Quay 3 | Affected | No fix yet: Fix deferred |
Timeline
- 2026-10-02 Threatist record created from CVE-2026-54651
- 2026-10-03 Alias added: GHSA-g9xf-7f8q-9mcj
References
More py-pdf Pypdf vulnerabilities
- TI-2023-18601 Infinite Loop when reading malformed objects in pypdf CVSS 3.1MEDIUM 6.5
- TI-2023-18305 Infinite Loop when a comment isn't followed by a character in pypdf CVSS 3.1MEDIUM 6.2
- TI-2026-42743 pypdf: Possible infinite loop for not terminated inline images CVSS 4.0HIGH 8.7
- TI-2026-42742 pypdf: Possible infinite loop for not terminated inline images (ASCII85 and ASCIIHex filter) CVSS 4.0HIGH 8.7
- TI-2026-65557 pypdf: Possible large memory usage when retrieving alphabetical page labels CVSS 4.0HIGH 8.7
- TI-2026-65556 pypdf: Possible long runtimes with large amount of embedded files CVSS 4.0HIGH 8.7
Sources
- CVE-2026-54651 · CVE Program
- CVE-2026-54651 · NVD
- FIRST EPSS
- GHSA-g9xf-7f8q-9mcj · GitHub Advisory Database · CC BY 4.0
- CVE-2026-54651 · Red Hat security data · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences