CVE-2021-45908Public exploit

Converter crash via cyclic LZW prefix traversal

Published Dec 28, 2021 · Updated Aug 4, 2024

Stack-based buffer overflow in gif2apng 1.9 allows local users to crash the converter by processing a crafted GIF file. In DecodeLZW, crafted LZW code values can make prefix[code] repeat indefinitely while pstr advances past the 4,097-byte str stack buffer. The target must invoke gif2apng on the crafted file; the published proof of concept causes a segmentation fault, while limited control over written data makes control-flow subversion unlikely.

CVSS severity7.8
High
EPSS probability0.73%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Stack-based buffer overflow in gif2apng 1.9 allows local users to crash the converter by processing a crafted GIF file. In DecodeLZW, crafted LZW code values can make prefix[code] repeat indefinitely while pstr advances past the 4,097-byte str stack buffer. The target must invoke gif2apng on the crafted file; the published proof of concept causes a segmentation fault, while limited control over written data makes control-flow subversion unlikely.

The record

CVE
CVE-2021-45908
Published
Dec 28, 2021
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-787, T1204.002
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. Dec 28, 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?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

7.8NIST NVDCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
6.8NIST NVDAV:N/AC:M/Au:N/C:P/I:P/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 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 exploitPublished

Weakness, pattern, technique

CWE-787Out-of-bounds Write
T1204.002Malicious File

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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