CVE-2021-34334

Denial of service via wrapped loop counter

Published Aug 9, 2021 · Updated Aug 4, 2024

Infinite-loop denial of service in Exiv2 0.27.4 and earlier allows attackers to hang metadata parsing with a crafted image file. CrwMap::decodeArray uses a 16-bit unsigned loop counter that wraps when the component size exceeds twice 0xffff, preventing the loop from reaching its exit condition. Exploitation requires a victim to run Exiv2 on the file, and the resulting impact is limited to a hang in that processing invocation.

CVSS severity5.5
Medium
EPSS probability1.11%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Infinite-loop denial of service in Exiv2 0.27.4 and earlier allows attackers to hang metadata parsing with a crafted image file. CrwMap::decodeArray uses a 16-bit unsigned loop counter that wraps when the component size exceeds twice 0xffff, preventing the loop from reaching its exit condition. Exploitation requires a victim to run Exiv2 on the file, and the resulting impact is limited to a hang in that processing invocation.

The record

CVE
CVE-2021-34334
Published
Aug 9, 2021
Updated
Aug 4, 2024
Vendor
Exiv2
Product
Exiv2
Classifications
CWE-835, CWE-190
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 9, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 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=<= 0.27.4

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

Exiv2 · Exiv2version=<= 0.27.4

Published CVSS scores

0.0GitHubCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:N
5.5Canonical UbuntuCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
5.5NIST NVDCVSS:3.1/AV:L/AC:L/PR:N/UI:R/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 exploitUnconfirmed

Weakness, pattern, technique

CWE-835Loop with Unreachable Exit Condition ('Infinite Loop')
CWE-190Integer Overflow or Wraparound

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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