CVE-2021-36531Public exploitNetwork attack vector

Application crash via unchecked GIF buffer read

Published Aug 27, 2021 · Updated Aug 4, 2024

Out-of-bounds read in MiniUPnP ngiflib 0.4 allows context-dependent attackers to crash GIF-processing applications via a crafted GIF. In NGIFLIB_NO_FILE mode, GetByte in ngiflib.c advances through the caller-supplied memory buffer without checking its boundary, producing a one-byte heap read past the allocation. The application must be built with NGIFLIB_NO_FILE and process the crafted file; the public report demonstrates an AddressSanitizer abort, while effects without the sanitizer are not established.

CVSS severity8.8
High
EPSS probability1.06%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Out-of-bounds read in MiniUPnP ngiflib 0.4 allows context-dependent attackers to crash GIF-processing applications via a crafted GIF. In NGIFLIB_NO_FILE mode, GetByte in ngiflib.c advances through the caller-supplied memory buffer without checking its boundary, producing a one-byte heap read past the allocation. The application must be built with NGIFLIB_NO_FILE and process the crafted file; the public report demonstrates an AddressSanitizer abort, while effects without the sanitizer are not established.

The record

CVE
CVE-2021-36531
Published
Aug 27, 2021
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-787, T1204.002
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 27, 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 vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

6.8NIST NVDAV:N/AC:M/Au:N/C:P/I:P/A:P
8.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
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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