pypdf: Possible large memory usage when parsing cross-reference streams
Only affects pypdf versions before 6.21.3 when opening PDFs that contain cross-reference streams, and a crafted file can drive memory use very high. Fixed in 6.21.3.
- Published
- Last modified
- Where the record stands: published, rejected by its publisher, or superseded by another id.What do these mean? →
- published
- Whether CISA lists it in its Known Exploited Vulnerabilities catalog: proof that attackers are using it.What do these mean? →
- Not listed in CISA KEV
- How many real-world setups can hit the bug, from the vendor's advisory and CISA data. It does not know your setup.What do these mean? →
- Specific setups only
- Fix
- Fixed in 6.21.3
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
- Exploitation: none
- Automatable: yes
- Technical impact: partial
Summary
pypdf, a free open-source pure-Python library for working with PDF files, is affected by this vulnerability. A specially crafted PDF can cause the library to use excessive amounts of memory when it is opened, which can slow or crash the program processing the file.
Summarized by anthropic/claude-haiku-5.5. Verify details against the original sources.
Read the original description
pypdf is a free and open-source pure-python PDF library. Prior to 6.21.3, pypdf can consume excessive memory while opening a crafted PDF containing cross-reference streams that declare very large entry counts. Highly compressible streams and /Prev chains can multiply the number of parsed entries across a document, while negative /Index counts can bypass the existing per-stream clamp. This issue is fixed in version 6.21.3.
Timeline
- CVE published
- First seen by cve.now
- CISA SSVC assessment
Exploitation: none · Automatable: yes · Technical impact: partial
- Record last updated
Affected versions
- py-pdf pypdf
fixed in 6.21.3
References 4
GitHub · py-pdf/pypdf
Questions about CVE-2026-119209
What does this mean?
A crafted PDF can make pypdf use a large amount of memory when it parses the file's cross-reference streams. This can lead to a denial of service.Source: github.com
Am I affected, and how do I check?
Affected versions are pypdf releases before 6.21.3, and the issue needs a file with cross-reference streams to be opened. To check a installed version, run pip show pypdf and compare the reported version with 6.21.3.Source: github.com
What should I do about it?
Upgrade pypdf to 6.21.3 or later. If the upgrade cannot be done yet, apply the changes from PR #4269.Source: github.com
Is it being exploited?
It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.Source: cve.now feed data