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Global Buffer Overflow (OOB Read) via Negative Pixel Index in UIL and XPM Writer

Moderate
dlemstra published GHSA-vpxv-r9pg-7gpr Feb 23, 2026

Package

ImageMagick (C/C++)

Affected versions

< 7.1.2-15
< 6.9.13-40

Patched versions

7.1.2-15
6.9.13-40

Description

The UIL and XPM image encoder do not validate the pixel index value returned by GetPixelIndex() before using it as an array subscript. In HDRI builds, Quantum is a floating-point type, so pixel index values can be negative. An attacker can craft an image with negative pixel index values to trigger a global buffer overflow read during conversion, leading to information disclosure or a process crash.

READ of size 1 at 0x55a8823a776e thread T0
    #0 0x55a880d01e85 in WriteUILImage coders/uil.c:355

READ of size 1 at 0x55fa1c04c66e thread T0
    #0 0x55fa1a9ee415 in WriteXPMImage coders/xpm.c:1135

Severity

Moderate

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality
Low
Integrity
None
Availability
Low

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:L

CVE ID

CVE-2026-25898

Weaknesses

Out-of-bounds Read

The product reads data past the end, or before the beginning, of the intended buffer. Learn more on MITRE.

Credits