CVE-2021-3508Public exploit

Process hang via unchecked backward xref search

Published Apr 28, 2021 · Updated Aug 3, 2024

Denial of service in PDFResurrect 0.22b allows local users to hang the application by processing a crafted PDF file. The get_xref_linear_skipped function repeatedly seeks backward while looking for an xref marker and fails to stop when fseek cannot move before the file start. A user must run the command-line utility on the malicious file; the resulting infinite loop consumes processing time and hangs that invocation.

CVSS severity5.5
Medium
EPSS probability0.76%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in PDFResurrect 0.22b allows local users to hang the application by processing a crafted PDF file. The get_xref_linear_skipped function repeatedly seeks backward while looking for an xref marker and fails to stop when fseek cannot move before the file start. A user must run the command-line utility on the malicious file; the resulting infinite loop consumes processing time and hangs that invocation.

The record

CVE
CVE-2021-3508
Published
Apr 28, 2021
Updated
Aug 3, 2024
Vendor
Matt Davis
Product
PDFResurrect
Classifications
CWE-835, T1204.002, T1499.004
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 28, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 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=PDFResurrect 0.23b

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

Matt Davis · PDFResurrectversion=PDFResurrect 0.23b

Published CVSS scores

5.5NIST NVDCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
4.3NIST NVDAV:N/AC:M/Au:N/C:N/I:N/A:P

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')
T1204.002Malicious File
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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