Security readout for executives and security teams
Plain-English summary
CVE-2026-22691 affects pypdf, a Python PDF library. Malformed PDFs with invalid startxref entries and excessive whitespace can cause unusually long processing times. The business impact is mainly service slowdown or resource consumption where applications process untrusted PDFs. The issue is low severity and fixed in pypdf 6.6.0.
Executive priority
Treat as a routine but worthwhile dependency update. It is low severity, but PDF-processing services exposed to untrusted uploads should patch promptly to reduce avoidable availability risk. No evidence of active exploitation is provided.
Technical view
pypdf versions before 6.6.0 can experience long runtimes when rebuilding cross-reference tables for malformed startxref entries. The advisory states only non-strict reading mode is affected. The issue maps to uncontrolled resource consumption and inefficient regular expression complexity classes. CVSS v4.0 is 2.7, with low availability impact and no confidentiality or integrity impact.
Likely exposure
Exposure is most relevant for Python services, document workflows, or user-upload features that parse untrusted PDFs using pypdf below 6.6.0 in non-strict mode. Systems that do not use pypdf, do not parse PDFs, or only use unaffected versions are not indicated as affected by the provided sources.
Exploitation context
The sources describe attacker-crafted PDFs causing long runtimes, but do not report active exploitation. The CVE is not listed as KEV in the provided bundle. Practical risk depends on whether attackers can submit PDFs to an affected application and trigger non-strict parsing.
Researcher notes
Key constraints are narrow: pypdf before 6.6.0, malformed startxref handling, cross-reference table rebuilding, lots of whitespace, and non-strict mode only. The public sources identify the patch release, pull request, and commit, but do not provide evidence of exploitation in the wild.
Mitigation direction
- Upgrade pypdf to version 6.6.0 or later.
- Prioritize internet-facing or automated PDF-processing services.
- Review vendor advisory and release notes before production rollout.
- If immediate upgrade is not possible, check vendor guidance for supported workarounds.
Validation and detection
- Inventory applications and containers using pypdf.
- Confirm installed pypdf versions are 6.6.0 or later.
- Identify whether non-strict PDF reading mode is used.
- Review upload and document-processing paths for untrusted PDF input.
- Monitor PDF-processing latency and resource usage for anomalies.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
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CWE-1333: Exact CWE lookup
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Open ATT&CK lookupCWE-400: Exact CWE lookup
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Open ATT&CK lookupCVE-2026-22691 mapping review
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Open ATT&CK lookup- Severity
- Low
- CVSS
- 2.7 (4.0)
- Known Exploited
- No
- Published
Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:U
CNA and ADP enrichment extracted from CVE v5
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CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:U——Primary CVE scoreVulnerability scoring details
Base CVSS 4.0 score
2.7LowVector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:U
Source materials
- CVE List V5 sourceCVE List V5
- https://github.com/py-pdf/pypdf/security/advisories/GHSA-4f6g-68pf-7vhvCVE reference · x_refsource_CONFIRM
- https://github.com/py-pdf/pypdf/pull/3594CVE reference · x_refsource_MISC
- https://github.com/py-pdf/pypdf/commit/294165726b646bb7799be1cc787f593f2fdbcf45CVE reference · x_refsource_MISC
- https://github.com/py-pdf/pypdf/releases/tag/6.6.0CVE reference · x_refsource_MISC
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.