CVE-2026-27024: py-pdf pypdf · Infinite Loop
Affects py-pdf pypdfSource CVE Database V5
Not known to be exploited · CVSS 6.9 Medium : upgrade to 6.7.1 when convenient.
Data as of 29 Oct 2026, 19:04 UTC
- EPSS
- 0.1% chance of exploitation in 30 days – higher than 8% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 6.7.1
CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:NExploitation evidence
Disclosed: evidence found.
CVE published 20 Feb 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 29 Oct 2026.
What to do
Upgrade py-pdf pypdf to 6.7.1.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| py-pdfpypdf | Affected
| Fixed in
|
AI-suggested
To mitigate CVE-2026-27024, organizations should immediately upgrade all instances of the pypdf library to version 6.7.1 or later, where the infinite loop vulnerability is fixed. For environments where immediate upgrading is not feasible, implement input validation and filtering to block or quarantine suspicious or untrusted PDF files before processing. Employ resource limits and timeouts on PDF parsing operations to prevent infinite loops from causing prolonged service disruption. Monitor CPU and memory usage of PDF processing services to detect anomalous behavior indicative of exploitation attempts. Additionally, consider sandboxing PDF processing components to isolate potential denial of service impacts. Regularly review and update third-party dependencies to incorporate security patches promptly. Finally, maintain awareness of any emerging exploits or related vulnerabilities in PDF libraries to adapt defenses accordingly.
Description
### Impact An attacker who uses this vulnerability can craft a PDF which leads to an infinite loop. This requires accessing the children of a `TreeObject`, for example as part of outlines. ### Patches This has been fixed in [pypdf==6.7.1](https://github.com/py-pdf/pypdf/releases/tag/6.7.1). ### Workarounds If you cannot upgrade yet, consider applying the changes from PR [#3645](https://github.com/py-pdf/pypdf/pull/3645).