CVE-2026-71852

Denial of service via unbounded CID width expansion

Published Aug 7, 2026 · Updated Aug 7, 2026

Excessive iteration in pypdf before 6.15.0 allows attackers to cause long runtimes and memory exhaustion with a crafted PDF. Font._collect_cid_character_widths expands every CID in attacker-controlled /W ranges and accumulates width entries without limiting either count. Exploitation requires a user or local process to extract text from the file, consuming CPU and memory until the operation stalls or its host loses availability.

CVSS severity4.8
Medium
EPSS probability0.13%
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 6.15.0 allows attackers to cause long runtimes and memory exhaustion with a crafted PDF. Font._collect_cid_character_widths expands every CID in attacker-controlled /W ranges and accumulates width entries without limiting either count. Exploitation requires a user or local process to extract text from the file, consuming CPU and memory until the operation stalls or its host loses availability.

The record

CVE
CVE-2026-71852
Published
Aug 7, 2026
Updated
Aug 7, 2026
Vendor
py-pdf
Product
pypdf
Classifications
CWE-834, T1204.002
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 7, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 7, 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=< 6.15.0

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

py-pdf · pypdfversion=< 6.15.0

Published CVSS scores

4.8GitHubCVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N

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.

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No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-834Excessive Iteration
T1204.002User Execution: Malicious File

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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