How severe is CVE-2026-22691?

CVE-2026-22691 has a CVSS 3.x base score of 5.3, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability low.

Is CVE-2026-22691 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (31st percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-22691?

CVE-2026-22691 affects Pypdf Project Pypdf. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-22691?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

Does CVE-2026-22691 have an EU (EUVD) identifier?

Yes. CVE-2026-22691 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-1691.

When was CVE-2026-22691 published?

CVE-2026-22691 was published on 2026-01-10 and last updated on 2026-06-17.

CVE-2026-22691

CVE-2026-22691 is a medium-severity vulnerability in Pypdf Project Pypdf with a CVSS 3.x base score of 5.3. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-400.

Key facts

Severity: Medium (CVSS 3.x base score 5.3)
CVSS v4: 2.7
EPSS exploit prediction: 0% (31st percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-1691
Weakness: CWE-400
Affected product: Pypdf Project Pypdf
Published: 2026-01-10
Last modified: 2026-06-17

Description

pypdf is a free and open-source pure-python PDF library. Prior to version 6.6.0, pypdf has possible long runtimes for malformed startxref. An attacker who uses this vulnerability can craft a PDF which leads to possibly long runtimes for invalid startxref entries. When rebuilding the cross-reference table, PDF files with lots of whitespace characters become problematic. Only the non-strict reading mode is affected. Only the non-strict reading mode is affected. This issue has been patched in version 6.6.0.

Frequently asked questions

What is CVE-2026-22691?: pypdf is a free and open-source pure-python PDF library. Prior to version 6.6.0, pypdf has possible long runtimes for malformed startxref. An attacker who uses this vulnerability can craft a PDF which leads to possibly long runtimes for invalid startxref entries. When rebuilding the cross-reference table, PDF files with lots of whitespace characters become problematic. Only the non-strict reading mode is affected. Only the non-strict reading mode is affected. This issue has been patched in version 6.6.0.
How severe is CVE-2026-22691?: CVE-2026-22691 has a CVSS 3.x base score of 5.3, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability low.
Is CVE-2026-22691 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (31st percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-22691?: CVE-2026-22691 affects Pypdf Project Pypdf. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-22691?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2026-22691 have an EU (EUVD) identifier?: Yes. CVE-2026-22691 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-1691.
When was CVE-2026-22691 published?: CVE-2026-22691 was published on 2026-01-10 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:pypdf_project:pypdf:*:*:*:*:*:*:*:*

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