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VulnerabilityPublished Updated

CVE-2026-22691: Pdfly · pypdf has possible long runtimes for malformed startxref

Affects pdflySource GCVE Database

0
Authoritative record:CVE-2026-22691· Low 2.7

Not known to be exploited · CVSS 2.7 Low : upgrade to 0.5.1_5 when convenient.

Data as of 26 Oct 2026, 18:58 UTC

CVSS 4.0 base score
2.7Low
How severe the flaw is on the 0–10 CVSS scale.
Patch
Available – fixed in 0.5.1_5
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:U

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 10 Jan 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: 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 26 Oct 2026.

What to do

Upgrade pdfly to 0.5.1_5.

Affected software

ProductAffectedFixed in
Homebrewpdflypkg:brew/pdflyOther threatsAffected
  • >=0.4.0 <0.5.1_5
Fixed in
  • 0.5.1_5

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

Description

### Impact An attacker who exploits this vulnerability can craft a PDF which leads to possibly long runtimes for invalid `startxref` entries. When rebuilding the cross-reference table, PDF files with lots of whitespace characters become problematic. Only the non-strict reading mode is affected. ### Patches This has been fixed in [pypdf==6.6.0](https://github.com/py-pdf/pypdf/releases/tag/6.6.0). ### Workarounds ```python from pypdf import PdfReader, PdfWriter # Instead of reader = PdfReader("file.pdf") # use the strict mode: reader = PdfReader("file.pdf", strict=True) # Instead of writer = PdfWriter(clone_from="file.pdf") # use an explicit strict reader: writer = PdfWriter(clone_from=PdfReader("file.pdf", strict=True)) ``` ### Resources This issue has been fixed in #3594.

References

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