CVE-2021-4214Public exploit

Utility crash via unchecked bytes-per-pixel indexing

Published Aug 24, 2022 · Updated Aug 3, 2024

Heap buffer overflow in libpng 1.6 allows local users to crash the pngimage utility by supplying a crafted PNG file. The compare_read function assumes its orig and row buffers each contain bpp bytes, then indexes past a one-byte allocation when bpp is two. Exploitation requires a user to run the test utility against the file; Debian notes that this CLI is not shipped in binary packages.

CVSS severity5.5
Medium
EPSS probability0.52%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Heap buffer overflow in libpng 1.6 allows local users to crash the pngimage utility by supplying a crafted PNG file. The compare_read function assumes its orig and row buffers each contain bpp bytes, then indexes past a one-byte allocation when bpp is two. Exploitation requires a user to run the test utility against the file; Debian notes that this CLI is not shipped in binary packages.

The record

CVE
CVE-2021-4214
Published
Aug 24, 2022
Updated
Aug 3, 2024
Vendor
PNG Development Group
Product
libpng
Classifications
CWE-787, CWE-120, T1204.002
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 24, 2022CVE 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

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=libpng v1.6

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

PNG Development Group · libpngversion=libpng v1.6

Published CVSS scores

5.5NIST National Vulnerability DatabaseCVSS: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.

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)
Vectorlocal
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-787Out-of-bounds Write
CWE-120Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')
T1204.002User Execution: Malicious File

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo