pypdf: Possible long runtimes for repeated malformed cross-reference entries (Follow-up)
pypdf versions before 6.21.2 are affected when parsing PDFs with repeated malformed cross-reference entries. The fix is in pypdf 6.21.2.
- 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- Where the record stands: published, rejected by its publisher, or superseded by another id.What do these mean?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 6.21.2
- 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
Summary
The pypdf Python library, a PDF processing tool, is affected when it parses PDF files with malformed cross-reference data. Processing a specially crafted file can cause it to run for a very long time, which may degrade or stall applications that rely on it.
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 6.21.2, an incomplete remediation for repeated malformed cross-reference entries in GHSA-55h5-xmcq-c37v could still trigger a complete PDF stream reload during each recovery attempt even when a recovery cache was present, causing crafted cross-reference streams to produce long runtimes. This issue is fixed in version 6.21.2.
Timeline
- CVE published
- First seen by cve.now
Affected versions
- py-pdf pypdf
fixed in 6.21.2
- pypdfPyPI
fixed in 6.21.2
References 4
GitHub · py-pdf/pypdf
Questions about CVE-2026-115585
What does this mean?
A crafted PDF with repeated malformed cross-reference entries can make pypdf run for a long time, using up resources. This is a denial of service through resource consumption.Source: github.com
Am I affected, and how do I check?
The affected range starts at version 0 and ends before 6.21.2. The vulnerable setup involves cross-reference streams with repeated malformed entries. To check a installed version, run pip show pypdf or python -c "import pypdf; print(pypdf.__version__)".Source: github.com
What should I do about it?
Upgrade pypdf to 6.21.2 or later, which contains the fix. If that is not possible, the advisory's workaround is to apply the changes from PR #4240.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