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VulnerabilityPublished Updated

CVE-2026-27024: py-pdf pypdf · Infinite Loop

Affects py-pdf pypdfSource CVE Database V5

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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

CVSS 4.0 base score
6.9Medium
How severe the flaw is on the 0–10 CVSS scale.
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:N

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 20 Feb 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq 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

ProductAffectedFixed in
py-pdfpypdfAffected
  • <6.7.1
Fixed in
  • 6.7.1

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).

References

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