pypdf has inefficient decoding of array-based streams
### Impact An attacker who uses this vulnerability can craft a PDF which leads to long runtimes and/or large memory usage. This requires accessing an array-based stream with lots of entries. ### Patches This has been fixed in [pypdf==6.9.1](https://github.com/py-pdf/pypdf/releases/tag/6.9.1). ### Workarounds If you cannot upgrade yet, consider applying the changes from PR [#3686](https://github.com/py-pdf/pypdf/pull/3686).
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describes (1)
Related CVEs.
| ID | severity | exploitable | ||
|---|---|---|---|---|
| CVE-2026-33123US | medium6.5 | — | ||
pypdf is a free and open-source pure-python PDF library. Versions prior to 6.9.1 allow an attacker to craft a malicious PDF which leads to long runtimes and/or large memory usage.… | ||||
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references
External citations — patches, advisories, analysis.
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