pypdf has possible long runtimes/large memory usage for large /ToUnicode streams
### Impact An attacker who uses this vulnerability can craft a PDF which leads to long runtimes and large memory consumption. This requires parsing the `/ToUnicode` entry of a font with unusually large values, for example during text extraction. ### Patches This has been fixed in [pypdf==6.7.1](https://github.com/py-pdf/pypdf/releases/tag/6.7.1). ### Workarounds If you cannot upgrade yet, consider applying the changes from PR [#3646](https://github.com/py-pdf/pypdf/pull/3646).
describes (1)
Related CVEs.
| ID | severity | exploitable | ||
|---|---|---|---|---|
| CVE-2026-27025US | medium5.5 | — | ||
pypdf is a free and open-source pure-python PDF library. Prior to 6.7.1, an attacker who uses this vulnerability can craft a PDF which leads to long runtimes and large memory consu… | ||||
references
External citations — patches, advisories, analysis.
- https://github.com/py-pdf/pypdfPACKAGE
- https://github.com/py-pdf/pypdf/commit/77d7b8d7cfbe8dd179858dfa42666f73fc6e57a2WEB
- https://github.com/py-pdf/pypdf/pull/3646WEB
- https://github.com/py-pdf/pypdf/releases/tag/6.7.1WEB
- https://github.com/py-pdf/pypdf/security/advisories/GHSA-wgvp-vg3v-2xq3WEB
- https://nvd.nist.gov/vuln/detail/CVE-2026-27025ADVISORY
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