pypdf manipulated LZWDecode streams can exhaust RAM
Priority LOW 35CWE-400Published · Updated
Key facts
- Attack vector
- Network
- 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: 4 without a fix
Attack profile from CVSS 4.0 · CNA. Fix status from CNA, GitHub and Red Hat. Impact type from CWE-400.
Summary
pypdf is a free and open-source pure-python PDF library. Prior to version 6.4.0, an attacker who uses this vulnerability can craft a PDF which leads to a memory usage of up to 1 GB per stream. This requires parsing the content stream of a page using the LZWDecode filter. This issue has been patched in version 6.4.0.
Why it matters now
Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00387 33rd percentileScored 2026-11-07
Fix Partial pypdf (py-pdf): 6.4.0pypdf (PyPI): 6.4.0Red Hat: 4 without a fix
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- Yes
- 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 6.4.0 | 6.4.0 | Patch available | CNA |
| — | pypdf (PyPI) | before 6.4.0 | 6.4.0 | Patch available | GHSA-m449-cwjh-6pw7 |
- pypdf Vendorpy-pdf Affected before 6.4.0 Fixed in 6.4.0 Patch available CNA
- pypdf (PyPI) Vendor— Affected before 6.4.0 Fixed in 6.4.0 Patch available GHSA-m449-cwjh-6pw7
Remediation
- Fix · CNA pypdf (py-pdf) Fixed in 6.4.0
- Fix · GHSA-m449-cwjh-6pw7 pypdf (PyPI) Fixed in 6.4.0 Advisory →
Vendor assessments
Red Hat
Red Hat rating: Moderate. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| 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 |
Timeline
- 2026-10-02 Threatist record created from CVE-2025-66019
- 2026-10-03 Alias added: GHSA-m449-cwjh-6pw7
References
Other 6
- https://github.com/py-pdf/pypdf/security/advisories/GHSA-m449-cwjh-6pw7
- https://github.com/py-pdf/pypdf/commit/96186725e5e6f237129a58a97cd19204a9ce40b2
- https://github.com/py-pdf/pypdf/releases/tag/6.4.0
- https://github.com/py-pdf/pypdf/security/advisories/GHSA-jfx9-29x2-rv3j
- https://aydinnyunus.github.io/2025/12/20/cve-2025-66019-pypdf-lzw-dos
- https://github.com/py-pdf/pypdf
More py-pdf vulnerabilities
- TI-2026-79334 Exponential SVG use expansion exhausts CPU and memory in fpdf2 CVSS 3.1MEDIUM 6.5
- 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-2022-08670 Manipulated inline images can cause Infinite Loop in PyPDF2 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
Sources
- CVE-2025-66019 · CVE Program
- CVE-2025-66019 · NVD
- FIRST EPSS
- GHSA-m449-cwjh-6pw7 · GitHub Advisory Database · CC BY 4.0
- CVE-2025-66019 · 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