How severe is CVE-2026-84309?

CVE-2026-84309 has a CVSS 3.x base score of 5.5, rated medium severity. It is exploitable over local access with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2026-84309 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (8th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-84309?

CVE-2026-84309 affects Pypdf Project Pypdf. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-84309?

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

When was CVE-2026-84309 published?

CVE-2026-84309 was published on 2026-09-01 and last updated on 2026-10-05.

CVE-2026-84309

CVE-2026-84309 is a medium-severity vulnerability in Pypdf Project Pypdf with a CVSS 3.x base score of 5.5. 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-835.

Key facts

Severity: Medium (CVSS 3.x base score 5.5)
CVSS v4: 6.9
EPSS exploit prediction: 0% (8th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-835
Affected product: Pypdf Project Pypdf
Published: 2026-09-01
Last modified: 2026-10-05

Description

pypdf is a free and open-source pure-python PDF library. Prior to 6.16.0, an attacker can craft a PDF whose cyclic tree structure causes pypdf/generic/_data_structures.py TreeObject.insert_child to follow /Next links indefinitely when a writing code path inserts a child, producing an infinite loop. This issue is fixed in version 6.16.0.

Frequently asked questions

What is CVE-2026-84309?: pypdf is a free and open-source pure-python PDF library. Prior to 6.16.0, an attacker can craft a PDF whose cyclic tree structure causes pypdf/generic/_data_structures.py TreeObject.insert_child to follow /Next links indefinitely when a writing code path inserts a child, producing an infinite loop. This issue is fixed in version 6.16.0.
How severe is CVE-2026-84309?: CVE-2026-84309 has a CVSS 3.x base score of 5.5, rated medium severity. It is exploitable over local access with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2026-84309 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (8th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-84309?: CVE-2026-84309 affects Pypdf Project Pypdf. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-84309?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2026-84309 published?: CVE-2026-84309 was published on 2026-09-01 and last updated on 2026-10-05.

References

Affected products (1)

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

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