CVE-2026-25646

Description

LIBPNG is a reference library for use in applications that read, create, and manipulate PNG (Portable Network Graphics) raster image files. Prior to 1.6.55, an out-of-bounds read vulnerability exists in the png_set_quantize() API function. When the function is called with no histogram and the number of colors in the palette is more than twice the maximum supported by the user's display, certain palettes will cause the function to enter into an infinite loop that reads past the end of an internal heap-allocated buffer. The images that trigger this vulnerability are valid per the PNG specification. This vulnerability is fixed in 1.6.55.

Status

Show unmaintained releases

Package	Ubuntu Release	Status
libpng	26.10 stonking	Not in release
	26.04 LTS resolute	Not in release
	25.10 questing	Not in release
	24.04 LTS noble	Not in release
	22.04 LTS jammy	Not in release
	16.04 LTS xenial	Fixed in 1.2.54-1ubuntu1.1+esm2
	14.04 LTS trusty	Fixed in 1.2.50-1ubuntu2.14.04.3+esm1
libpng1.6	26.10 stonking	Fixed in 1.6.55-1
	26.04 LTS resolute	Fixed in 1.6.55-1
	25.10 questing	Fixed in 1.6.50-1ubuntu0.4
	24.04 LTS noble	Fixed in 1.6.43-5ubuntu0.5
	22.04 LTS jammy	Fixed in 1.6.37-3ubuntu0.4
	20.04 LTS focal	Fixed in 1.6.37-2ubuntu0.1~esm2
	18.04 LTS bionic	Fixed in 1.6.34-1ubuntu0.18.04.2+esm2
	16.04 LTS xenial	Fixed in 1.6.20-2ubuntu0.1~esm3
firefox	26.10 stonking	Not affected
	26.04 LTS resolute	Not affected
	25.10 questing	Not affected
	24.04 LTS noble	Not affected
	22.04 LTS jammy	Not affected
thunderbird	26.10 stonking	Not affected
	26.04 LTS resolute	Not affected
	25.10 questing	Not affected
	24.04 LTS noble	Not affected
	22.04 LTS jammy	Not affected
chromium-browser	26.10 stonking	Not affected
	26.04 LTS resolute	Not affected
	25.10 questing	Not affected
	24.04 LTS noble	Not affected
	22.04 LTS jammy	Not affected

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Patch details

For informational purposes only. We recommend not to cherry-pick updates. How can I get the fixes?

Package	Patch details
libpng1.6	Upstream: 01d03b8

Severity score breakdown

CVSS version:

Base score 8.3 · High

Base metrics

Parameter	Value
Attack vector	Network
Attack complexity	High
Attack requirements	Present
Privileges required	None
User interaction	None
Vulnerable system - Confidentiality impact	Low
Vulnerable system - Integrity impact	Low
Vulnerable system - Availability impact	High
Subsequent system - Confidentiality impact	None
Subsequent system - Integrity impact	None
Subsequent system - Availability impact	None

Scores

Parameter	Value
Base score	8.3 · High
Base + Threat score	-
Base + Environmental score	-
Base + Threat + Environmental score	-

Vector: CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:L/VI:L/VA:H/SC:N/SI:N/SA:N

Base score 7.0 · High

Base metrics

Parameter	Value
Attack vector	Network
Attack complexity	High
Privileges required	None
User interaction	None
Scope	Unchanged
Confidentiality impact	Low
Integrity impact	Low
Availability impact	High

Scores

Parameter	Value
Base score	7.0 · High
Exploitability score	-
Impact score	-

Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:H

References

Related Ubuntu Security Notices (USN)

USN-8035-1
libpng vulnerabilities
12 February 2026

USN-8039-1
libpng vulnerability
12 February 2026

USN-8081-1
libpng vulnerabilities
11 March 2026