CVE-2026-22691: Pdfly · pypdf has possible long runtimes for malformed startxref
Affects pdflySource GCVE Database
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
- 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:UExploitation evidence
Disclosed: evidence found.
CVE published 10 Jan 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: 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 26 Oct 2026.
What to do
Upgrade pdfly to 0.5.1_5.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
Homebrewpdflypkg:brew/pdflyOther threats | Affected
| Fixed in
|
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
- github.com/py-pdf/pypdf/security/advisories/GHSA-4f6g-68pf-7vhv (opens in a new tab)
- nvd.nist.gov/vuln/detail/CVE-2026-22691 (opens in a new tab)
- github.com/py-pdf/pypdf/pull/3594 (opens in a new tab)
- github.com/py-pdf/pypdf/commit/294165726b646bb7799be1cc787f593f2fdbcf45 (opens in a new tab)
- github.com/py-pdf/pypdf (opens in a new tab)
- github.com/py-pdf/pypdf/releases/tag/6.6.0 (opens in a new tab)