CVE-2026-27025
Denial of Service via Resource Exhaustion in pypdf /ToUnicode Parsing
Publication date: 2026-02-20
Last updated on: 2026-02-24
Assigner: GitHub, Inc.
Description
Description
CVSS Scores
EPSS Scores
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Meta Information
Affected Vendors & Products
| Vendor | Product | Version / Range |
|---|---|---|
| pypdf_project | pypdf | to 6.7.1 (exc) |
Helpful Resources
Exploitability
| CWE ID | Description |
|---|---|
| CWE-834 | The product performs an iteration or loop without sufficiently limiting the number of times that the loop is executed. |
Attack-Flow Graph
AI Powered Q&A
Can you explain this vulnerability to me?
This vulnerability exists in the pypdf library, a pure-python PDF library. Before version 6.7.1, an attacker could craft a specially designed PDF file that exploits the parsing of the /ToUnicode entry of a font with unusually large values. When such a PDF is processed, it can cause the library to consume excessive memory and run for a very long time.
How can this vulnerability impact me? :
The impact of this vulnerability is that processing a maliciously crafted PDF can lead to long runtimes and large memory consumption. This can degrade system performance, potentially causing denial of service conditions or resource exhaustion on systems that use the vulnerable pypdf versions.
How does this vulnerability affect compliance with common standards and regulations (like GDPR, HIPAA)?:
I don't know
How can this vulnerability be detected on my network or system? Can you suggest some commands?
I don't know
What immediate steps should I take to mitigate this vulnerability?
To mitigate this vulnerability, you should upgrade the pypdf library to version 6.7.1 or later, where the issue has been fixed.