pypdf: Possible long runtimes when generating appearance streams
### Impact An attacker who uses this vulnerability can craft a PDF which leads to long runtimes. This requires updating form field values with flattening enabled, which triggers appearance stream generation. ### Patches This has been fixed in [pypdf==6.19.0](https://github.com/py-pdf/pypdf/releases/tag/6.19.0). ### Workarounds If you cannot upgrade yet, consider applying the changes from PR [#4087](https://github.com/py-pdf/pypdf/pull/4087).
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describes (1)
Related CVEs.
| ID | severity | exploitable | ||
|---|---|---|---|---|
| CVE-2026-102998US | high7.5 | — | ||
pypdf is a free and open-source pure-python PDF library. Prior to 6.19.0, a crafted PDF with form field values can cause pypdf/generic/_appearance_stream.py appearance-stream gener… | ||||
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references
External citations — patches, advisories, analysis.
- https://github.com/advisories/GHSA-php9-fj8v-98fjADVISORY
- https://github.com/py-pdf/pypdfPACKAGE
- https://github.com/py-pdf/pypdf/commit/959467a9b95be83e2dc5ae873ece5f371263ede7WEB
- https://github.com/py-pdf/pypdf/pull/4087WEB
- https://github.com/py-pdf/pypdf/releases/tag/6.19.0WEB
- https://github.com/py-pdf/pypdf/security/advisories/GHSA-php9-fj8v-98fjWEB
- https://nvd.nist.gov/vuln/detail/CVE-2026-102998ADVISORY
- https://pypi.org/project/pypdfPACKAGE
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