CVE-2023-36807Public exploit

Process hang via invalid object token parsing

Published Jun 30, 2023 · Updated Nov 6, 2024

Infinite loop in PyPDF2 2.10.5 allows attackers to hang the current process by supplying a malformed PDF during metadata extraction. The read_object dispatcher treats every unrecognized token as a number or indirect reference instead of rejecting it, so dictionary parsing can revisit the same stream position. Processing the crafted file, including reading its metadata, consumes one CPU core and leaves the calling process hung.

CVSS severity6.2
Medium
EPSS probability0.57%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Infinite loop in PyPDF2 2.10.5 allows attackers to hang the current process by supplying a malformed PDF during metadata extraction. The read_object dispatcher treats every unrecognized token as a number or indirect reference instead of rejecting it, so dictionary parsing can revisit the same stream position. Processing the crafted file, including reading its metadata, consumes one CPU core and leaves the calling process hung.

The record

CVE
CVE-2023-36807
Published
Jun 30, 2023
Updated
Nov 6, 2024
Vendor
py-pdf
Product
pypdf
Classifications
CWE-835, T1499.004
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jun 30, 2023CVE publishedPublication date reported by the CVE source.
  2. Nov 6, 2024Record 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=2.10.5

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

py-pdf · pypdfversion=2.10.5

Published CVSS scores

6.2GitHubCVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

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

Weakness, pattern, technique

CWE-835Loop with Unreachable Exit Condition ('Infinite Loop')
T1499.004Application or System Exploitation

Public exploit references

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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