CVE-2026-41168Network attack vector

Long runtimes via unchecked PDF stream counts

Published Apr 22, 2026 · Updated Apr 22, 2026

Excessive iteration in pypdf before 6.10.1 allows remote attackers to cause long runtimes by supplying a crafted PDF file. The PDF reader trusts oversized /Size and /N counts in cross-reference and object streams, then iterates according to values that exceed the stream's possible entry count. Exploitation requires an application to parse the attacker-controlled file, consuming processing time without reported data disclosure or modification.

CVSS severity6.9
Medium
EPSS probability0.30%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Excessive iteration in pypdf before 6.10.1 allows remote attackers to cause long runtimes by supplying a crafted PDF file. The PDF reader trusts oversized /Size and /N counts in cross-reference and object streams, then iterates according to values that exceed the stream's possible entry count. Exploitation requires an application to parse the attacker-controlled file, consuming processing time without reported data disclosure or modification.

The record

CVE
CVE-2026-41168
Published
Apr 22, 2026
Updated
Apr 22, 2026
Vendor
py-pdf
Product
pypdf
Classifications
CWE-834, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 22, 2026CVE publishedPublication date reported by the CVE source.
  2. Apr 22, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 6.10.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

py-pdf · pypdfversion=< 6.10.1

Published CVSS scores

6.9GitHub, Inc.CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N
5.3NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-834Excessive Iteration
T1499.004Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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