---
id: CVE-2025-55197
aliases:
  - GHSA-7hfw-26vp-jp8m
  - PYSEC-2026-1830
title: PyPDF's Manipulated FlateDecode streams can exhaust RAM
summary: PyPDF's Manipulated FlateDecode streams can exhaust RAM
severity: medium
vendor: pypdf
product: pypdf
ecosystem: pip
affected:
  - pypdf < 6.0.0
patched:
  - pypdf 6.0.0
published: '2025-08-13'
updated: '2026-09-10'
sourceUpdated: '2026-09-10T03:50:26.651449913Z'
source: OSV
sourceUrl: 'https://osv.dev/vulnerability/GHSA-7hfw-26vp-jp8m'
references:
  - url: 'https://github.com/py-pdf/pypdf/security/advisories/GHSA-7hfw-26vp-jp8m'
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2025-55197'
  - url: 'https://github.com/py-pdf/pypdf/issues/3429'
  - url: 'https://github.com/py-pdf/pypdf/pull/3430'
  - url: 'https://github.com/py-pdf/pypdf'
  - url: >-
      https://github.com/py-pdf/pypdf/blob/0dd57738bbdcdb63f0fb43d8a6b3d222b6946595/pypdf/filters.py#L72-L143
  - url: 'https://github.com/py-pdf/pypdf/releases/tag/6.0.0'
tags:
  - osv
  - pip
epss: 0.00459
epssPercentile: 0.37047
ingestedAt: '2026-07-08T18:25:47.010Z'
---

## Overview

### Impact
An attacker who uses this vulnerability can craft a PDF which leads to the RAM being exhausted. This requires just reading the file if a series of FlateDecode filters is used on a malicious cross-reference stream. Other content streams are affected on explicit access.

### Patches
This has been fixed in [pypdf==6.0.0](https://github.com/py-pdf/pypdf/releases/tag/6.0.0).

### Workarounds
If you cannot upgrade yet, you might want to implement the workaround for `pypdf.filters.decompress` yourself: https://github.com/py-pdf/pypdf/blob/0dd57738bbdcdb63f0fb43d8a6b3d222b6946595/pypdf/filters.py#L72-L143

### References
This issue has been reported in #3429 and fixed in #3430.

## Affected packages

- `pypdf < 6.0.0`

## Remediation

Upgrade to a patched release:

- `pypdf 6.0.0`