pypdf: Possible long runtimes for zero-only width values in cross-reference streamsuntimes for zero-only width values in cross-reference streams
### Impact An attacker who uses this vulnerability can craft a PDF which leads to long runtimes. This requires cross-reference streams with `/W [0 0 0]` values and large `/Size` values. ### Patches This has been fixed in [pypdf==6.12.0](https://github.com/py-pdf/pypdf/releases/tag/6.12.0). ### Workarounds If developers are unable to upgrade their apps immediately, they should consider applying the changes from PR [#3791](https://github.com/py-pdf/pypdf/pull/3791).
describes (1)
Related CVEs.
| ID | severity | exploitable | ||
|---|---|---|---|---|
| CVE-2026-48156US | low3.3 | — | ||
pypdf is a free and open-source pure-python PDF library. Prior to 6.12.0, an attacker who uses this vulnerability can craft a PDF which leads to long runtimes. This requires cross-… | ||||
references
External citations — patches, advisories, analysis.
- https://github.com/py-pdf/pypdfPACKAGE
- https://github.com/py-pdf/pypdf/commit/507d7c9aa6ea83389b954b9c3c0c528fe5d5da70WEB
- https://github.com/py-pdf/pypdf/pull/3791WEB
- https://github.com/py-pdf/pypdf/releases/tag/6.12.0WEB
- https://github.com/py-pdf/pypdf/security/advisories/GHSA-248m-82v9-q6g6WEB
- https://nvd.nist.gov/vuln/detail/CVE-2026-48156ADVISORY
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