CVE-2026-84309: pypdf · Possible infinite loop for TreeObject.insert_child
Affects pdflySource GCVE Database
Not known to be exploited · CVSS 6.9 Medium : upgrade to 0.5.1_25 when convenient.
Data as of 26 Oct 2026, 14:05 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 0.5.1_25
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 1 Sep 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_25.
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 uses this vulnerability can craft a PDF which leads to an infinite loop. This requires a (usually writing) code path where `TreeObject.insert_child` is involved. ### Patches This has been fixed in [pypdf==6.16.0](https://github.com/py-pdf/pypdf/releases/tag/6.16.0). ### Workarounds If you cannot upgrade yet, consider applying the changes from PR [#3964](https://github.com/py-pdf/pypdf/pull/3964).
References
- github.com/py-pdf/pypdf/security/advisories/GHSA-jp53-mhqp-8xcg (opens in a new tab)
- github.com/py-pdf/pypdf/pull/3964 (opens in a new tab)
- github.com/py-pdf/pypdf/commit/c9ba557d565d57c53a0b3a0be06c0a4c29b0559b (opens in a new tab)
- github.com/py-pdf/pypdf (opens in a new tab)
- github.com/py-pdf/pypdf/releases/tag/6.16.0 (opens in a new tab)