CVE-2026-48156: pypdf — Fix

Description

pypdf is a free and open-source pure-python PDF library. Prior to 6.12.0, an attacker who uses this vulnerability can craft a PDF which leads to long runtimes. This requires cross-reference streams with /W [0 0 0] values and large /Size values. This vulnerability is fixed in 6.12.0.

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CVSS v3.1 Score

3.3

LOW

CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:L

EPSS — Exploit Prediction

0.0012

Probability of exploitation

0.02%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-834 CWE-834

Affected Products

Vendor	Product	Versions
pypdf_project	pypdf	< 6.12.0

References

Advisories & Patches

https://github.com/py-pdf/pypdf/pull/3791 https://github.com/py-pdf/pypdf/security/advisories/GHSA-248m-82v9-q6g6

Other References

https://github.com/py-pdf/pypdf/releases/tag/6.12.0

Frequently Asked Questions

What is CVE-2026-48156? +

pypdf is a free and open-source pure-python PDF library. Prior to 6.12.0, an attacker who uses this vulnerability can craft a PDF which leads to long runtimes. This requires cross-reference streams with /W [0 0 0] values and large /Size values. This vulnerability is fixed in 6.12.0. It has a CVSS v3.1 base score of 3.3 (LOW).

How severe is CVE-2026-48156? +

CVE-2026-48156 has a CVSS v3.1 score of 3.3 out of 10, rated LOW. This is a low-severity vulnerability with limited impact. The EPSS score is 0.0012, placing it in the 0th percentile for exploitation probability.

What products are affected by CVE-2026-48156? +

CVE-2026-48156 affects products from pypdf_project, specifically: pypdf. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2026-48156? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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