pypdf: Manipulated FlateDecode XFA streams can exhaust RAM
### Impact An attacker who uses this vulnerability can craft a PDF which leads to the RAM being exhausted. This requires accessing the `xfa` property of a reader or writer and the corresponding stream being compressed using `/FlateDecode`. ### Patches This has been fixed in [pypdf==6.7.3](https://github.com/py-pdf/pypdf/releases/tag/6.7.3). ### Workarounds If projects cannot upgrade yet, consider applying the changes from PR [#3658](https://github.com/py-pdf/pypdf/pull/3658).
describes (1)
Related CVEs.
| ID | severity | exploitable | ||
|---|---|---|---|---|
| CVE-2026-27888US | high7.5 | — | ||
pypdf is a free and open-source pure-python PDF library. Prior to 6.7.3, an attacker who uses this vulnerability can craft a PDF which leads to the RAM being exhausted. This requir… | ||||
references
External citations — patches, advisories, analysis.
- https://github.com/advisories/GHSA-x7hp-r3qg-r3cjADVISORY
- https://github.com/py-pdf/pypdfPACKAGE
- https://github.com/py-pdf/pypdf/commit/7a4c8246ed48d9d328fb596942271da47b6d109cWEB
- https://github.com/py-pdf/pypdf/pull/3658WEB
- https://github.com/py-pdf/pypdf/releases/tag/6.7.3WEB
- https://github.com/py-pdf/pypdf/security/advisories/GHSA-x7hp-r3qg-r3cjWEB
- https://nvd.nist.gov/vuln/detail/CVE-2026-27888ADVISORY
- https://pypi.org/project/pypdfPACKAGE
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