6.9

CVSS Score

4.0

-

CVSS Score

Basic Information

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CVE-2026-48735

CVE-2026-48735: pypdf: Manipulated XMP metadata streams can exhaust RAM

pypdf is a free and open-source pure-python PDF library. Prior to 6.12.1, an attacker who uses this vulnerability can craft a PDF which leads to large memory usage. This requires parsing large XMP metadata, possibly with lots of unnecessary elements. This vulnerability is fixed in 6.12.1.

(GitHub Advisory)

Miggo Vulnerability Database

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CVE-2026-48735

CVE-2026-48735:

6.9

CVSS Score

4.0

-

CVSS Score

Basic Information

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Technical Details

SSVC / BOD 26-04 ↗

Exploitation NoneAutomatable NoTech Impact Partial

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Package Name	Ecosystem	Vulnerable Versions	First Patched Version
pypdf	pip	< 6.12.1	6.12.1

Technical Details

Vulnerability Intelligence
Miggo AI

Root Cause Analysis

The vulnerability lies in the parsing of XMP metadata in the pypdf library, where a crafted PDF with a malicious XMP stream can cause excessive memory usage. The root cause is in the pypdf.xmp.XmpInformation.__init__ function, which, before the patch, would read and parse the entire XMP data stream without any limits on its size or the number of XML elements.

The fix, as seen in commit 4f29b462664820df861cfc5e029ef72364d523d9, mitigates this by introducing two key limits:

A check on the input stream's length (XMP_MAX_INPUT_LENGTH) is added in XmpInformation.__init__ before parsing.
A limit on the number of XML elements (XMP_MAX_ELEMENT_COUNT) is enforced by adding a custom start_element_handler to the _XmpBuilder class, which is used for XML parsing.

During exploitation, a runtime profiler would show the XmpInformation.__init__ function being called, which would then lead to uncontrolled memory allocation as it attempts to parse the malicious XMP data. Therefore, this function is the primary indicator of the vulnerability being triggered.

Vulnerable functions

XmpInformation.__init__

pypdf/xmp.py

The `__init__` method of the `XmpInformation` class is responsible for parsing XMP metadata. In vulnerable versions, it reads the entire XMP stream and parses it as XML without validating the size of the stream or the number of XML elements. An attacker could provide a malicious XMP stream that is excessively large or contains a vast number of elements, leading to high memory consumption and a denial-of-service condition. The patch introduces checks to limit both the input stream size and the number of XML elements.

Vulnerability Intelligence
Miggo AI

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WAF Protection Rules

WAF Rule

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Reasoning

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