CVE-2020-11721Public exploitNetwork attack vector

Application crash via uninitialized PNG rows pointer

Published Apr 12, 2020 · Updated Aug 4, 2024

An invalid free in libsixel 1.8.6 allows attackers to crash applications that process a crafted PNG image with the load_png decoder. The rows pointer in loader.c is left uninitialized, and cleanup passes its indeterminate value to free after PNG decoding fails. Exploitation requires an application using the vulnerable library to process attacker-supplied PNG data; the demonstrated consequence is process termination.

CVSS severity6.5
Medium
EPSS probability0.94%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

An invalid free in libsixel 1.8.6 allows attackers to crash applications that process a crafted PNG image with the load_png decoder. The rows pointer in loader.c is left uninitialized, and cleanup passes its indeterminate value to free after PNG decoding fails. Exploitation requires an application using the vulnerable library to process attacker-supplied PNG data; the demonstrated consequence is process termination.

The record

CVE
CVE-2020-11721
Published
Apr 12, 2020
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-824, T1499.004, T1204.002
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 12, 2020CVE 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

6.5NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
4.3NVDAV: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)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-824Access of Uninitialized Pointer
T1499.004Application or System Exploitation
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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