Bug 2441495 (CVE-2026-27026)

Summary: CVE-2026-27026 pypdf: pypdf: Denial of Service via malformed PDF /FlateDecode stream
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: anpicker, bbrownin, bparees, hasun, jfula, jkoehler, jowilson, jwong, lphiri, nyancey, omaciel, ometelka, ptisnovs, syedriko, teagle, ttakamiy, xdharmai
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in pypdf, a pure-python PDF library. A remote attacker can exploit this vulnerability by crafting a malicious PDF file containing a malformed /FlateDecode stream. This stream, which is used for data compression within the PDF, can cause excessively long processing times when decompressed byte-by-byte. This leads to a Denial of Service (DoS), making the affected system or application unresponsive.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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Description OSIDB Bzimport 2026-02-20 22:02:01 UTC
pypdf is a free and open-source pure-python PDF library. Prior to 6.7.1, an attacker who uses this vulnerability can craft a PDF which leads to long runtimes. This requires a malformed /FlateDecode stream, where the byte-by-byte decompression is used. This vulnerability is fixed in 6.7.1.