py-pdf pypdf up to 6.18.0 ToUnicode Mapping pypdf/_cmap.py parse_bfchar memory allocation

Summaryinfo

A vulnerability categorized as problematic has been discovered in py-pdf pypdf up to 6.18.0. This vulnerability affects the function parse_bfchar of the file pypdf/_cmap.py of the component ToUnicode Mapping. Such manipulation leads to memory allocation. This vulnerability is listed as CVE-2026-102995. The attack may be performed from remote. There is no available exploit. It is advisable to upgrade the affected component.

Detailsinfo

A vulnerability was found in py-pdf pypdf up to 6.18.0 and classified as problematic. Affected by this issue is the function parse_bfchar of the file pypdf/_cmap.py of the component ToUnicode Mapping. The manipulation with an unknown input leads to a memory allocation vulnerability. Using CWE to declare the problem leads to CWE-789. The product allocates memory based on an untrusted, large size value, but it does not ensure that the size is within expected limits, allowing arbitrary amounts of memory to be allocated. Impacted is availability. CVE summarizes:

pypdf is a free and open-source pure-python PDF library. Prior to 6.18.1, a crafted PDF can place unusually large source-code or destination-string tokens in a font /ToUnicode mapping, causing pypdf/_cmap.py parse_bfchar to decode and retain oversized values during operations such as text extraction and consume excessive memory. This is a second follow-up to earlier /ToUnicode resource-consumption fixes and is limited to the remaining token-length path. This issue is fixed in version 6.18.1.

The advisory is shared for download at github.com. This vulnerability is handled as CVE-2026-102995 since 09/29/2026. The exploitation is known to be easy. The attack may be launched remotely. No form of authentication is required for exploitation. Successful exploitation requires user interaction by the victim. There are known technical details, but no exploit is available.

Upgrading to version 6.18.1 eliminates this vulnerability.

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Productinfo

Vendor

• py-pdf

Name

• pypdf

Version

• 6.0
• 6.1
• 6.2
• 6.3
• 6.4
• 6.5
• 6.6
• 6.7
• 6.8
• 6.9
• 6.10
• 6.11
• 6.12
• 6.13
• 6.14
• 6.15
• 6.16
• 6.17
• 6.18.0

Website

• Product: https://github.com/py-pdf/pypdf/

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