Summary
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.
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.
Crafted input forces the application to consume excessive CPU, memory, or other resources, degrading or denying service. Typical impact: denial of service.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
Remediation advice
This has been fixed in pypdf==6.0.0.
Frequently Asked Questions
- What is CVE-2025-55197? CVE-2025-55197 is a medium-severity uncontrolled resource consumption vulnerability in pypdf (pip), affecting versions < 6.0.0. It is fixed in 6.0.0. Crafted input forces the application to consume excessive CPU, memory, or other resources, degrading or denying service.
- Which versions of pypdf are affected by CVE-2025-55197? pypdf (pip) versions < 6.0.0 is affected.
- Is there a fix for CVE-2025-55197? Yes. CVE-2025-55197 is fixed in 6.0.0. Upgrade to this version or later.
- Is CVE-2025-55197 exploitable, and should I be worried? Whether CVE-2025-55197 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2025-55197 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2025-55197? Upgrade
pypdfto 6.0.0 or later.