PYSEC-2026-3019
pypdf: manipulated stream length values can exhaust RAM
Quick fix
PYSEC-2026-3019 — pypdf: upgrade to the fixed version with the command below.
pip install --upgrade 'pypdf>=6.8.0'Details
### Impact
An attacker who uses this vulnerability can craft a PDF which leads to large memory usage. This requires parsing a content stream with a rather large `/Length` value, regardless of the actual data length inside the stream.
### Patches This has been fixed in [pypdf==6.8.0](https://github.com/py-pdf/pypdf/releases/tag/6.8.0).
### Workarounds If you cannot upgrade yet, consider applying the changes from PR [#3675](https://github.com/py-pdf/pypdf/pull/3675).
As far as we are aware, this mostly affects reading from buffers of unknown size, as returned by `open("file.pdf", mode="rb")` for example. Passing a file path or a `BytesIO` buffer to *pypdf* instead does not seem to trigger the vulnerability.
Are you affected?
Enter the version of the package you're using.
Affected packages
References
- https://github.com/py-pdf/pypdf/security/advisories/GHSA-hqmh-ppp3-xvm7[WEB]
- https://nvd.nist.gov/vuln/detail/CVE-2026-31826[ADVISORY]
- https://github.com/py-pdf/pypdf/pull/3675[WEB]
- https://github.com/py-pdf/pypdf/commit/3c550b3196adeba1506a26e57c09c09fac75e9aa[WEB]
- https://github.com/py-pdf/pypdf[PACKAGE]
- https://github.com/py-pdf/pypdf/releases/tag/6.8.0[WEB]
- https://pypi.org/project/pypdf[PACKAGE]
- https://github.com/advisories/GHSA-hqmh-ppp3-xvm7[ADVISORY]