LibPNG 1.6.55-Pre: OOB Read in png_set_quantize() w/ no hist leads to infinite loop
CVE-2026-25646 Published on February 10, 2026

LIBPNG has a heap buffer overflow in png_set_quantize
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.

NVD

Vulnerability Analysis

CVE-2026-25646 is exploitable with network access, and does not require authorization privileges or user interaction. This vulnerability is consided to have a high level of attack complexity. Public availability of a proof of concept (POC) exploit exists for CVE-2026-25646. The potential impact of an exploit of this vulnerability is considered to have a small impact on confidentiality and integrity, and a high impact on availability.

Attack Vector:
NETWORK
Attack Complexity:
HIGH
Privileges Required:
NONE
User Interaction:
NONE
Scope:
UNCHANGED
Confidentiality Impact:
LOW
Integrity Impact:
LOW
Availability Impact:
HIGH

Weakness Types

Heap-based Buffer Overflow

A heap overflow condition is a buffer overflow, where the buffer that can be overwritten is allocated in the heap portion of memory, generally meaning that the buffer was allocated using a routine such as malloc().

Buffer Over-read

The software reads from a buffer using buffer access mechanisms such as indexes or pointers that reference memory locations after the targeted buffer. This typically occurs when the pointer or its index is incremented to a position beyond the bounds of the buffer or when pointer arithmetic results in a position outside of the valid memory location to name a few. This may result in exposure of sensitive information or possibly a crash.

Out-of-bounds Read

The software reads data past the end, or before the beginning, of the intended buffer. Typically, this can allow attackers to read sensitive information from other memory locations or cause a crash. A crash can occur when the code reads a variable amount of data and assumes that a sentinel exists to stop the read operation, such as a NUL in a string. The expected sentinel might not be located in the out-of-bounds memory, causing excessive data to be read, leading to a segmentation fault or a buffer overflow. The software may modify an index or perform pointer arithmetic that references a memory location that is outside of the boundaries of the buffer. A subsequent read operation then produces undefined or unexpected results.


Products Associated with CVE-2026-25646

You can be notified by email with stack.watch whenever vulnerabilities like CVE-2026-25646 are published in these products:

Canonical Ubuntu Linux
 
Libpng
 
Oracle
 
Red Hat Rhel Els
 
Red Hat Openjdk Els
 
Red Hat Openshift
 
Red Hat Enterprise Linux Eus
 
Red Hat Enterprise Linux (RHEL)
 
Red Hat Rhel Aus
 
Red Hat Rhel Eus Long Life
 
Red Hat Rhel E4s
 
Red Hat Rhel Tus
 
Red Hat Rhel Eus
 
Red Hat Ai Inference Server
 
Red Hat Openjdk
 
Red Hat Ceph Storage
 
Red Hat Discovery
 
Red Hat Hummingbird
 

Affected Versions

pnggroup libpng: Red Hat Enterprise Linux Server (v. 7 ELS): Red Hat OpenJDK 11 ELS for RHEL 7: Red Hat Enterprise Linux Server Optional (v. 7 ELS): Red Hat OpenJDK 11 ELS for RHEL 8: Red Hat OpenShift Container Platform 4.12: Red Hat OpenJDK 11 ELS for RHEL 9: Red Hat OpenShift Container Platform 4.13: Red Hat OpenShift Container Platform 4.14: Red Hat OpenShift Container Platform 4.15: Red Hat OpenShift Container Platform 4.16: Red Hat OpenShift Container Platform 4.17: Red Hat OpenShift Container Platform 4.18: Red Hat OpenShift Container Platform 4.19: Red Hat Enterprise Linux AppStream EUS (v. 10.0): Red Hat Enterprise Linux AppStream (v. 10): Red Hat Enterprise Linux AppStream (v. 8): Red Hat Enterprise Linux AppStream AUS (v. 8.2): Red Hat Enterprise Linux AppStream AUS (v.8.4): Red Hat Enterprise Linux AppStream EUS EXTENSION (v.8.4): Red Hat Enterprise Linux AppStream AUS (v.8.6): Red Hat Enterprise Linux AppStream E4S (v.8.6): Red Hat Enterprise Linux AppStream TUS (v.8.6): Red Hat Enterprise Linux AppStream E4S (v.8.8): Red Hat Enterprise Linux AppStream TUS (v.8.8): Red Hat Enterprise Linux AppStream E4S (v.9.0): Red Hat Enterprise Linux AppStream E4S (v.9.2): Red Hat Enterprise Linux AppStream EUS (v.9.4): Red Hat Enterprise Linux AppStream EUS (v.9.6): Red Hat Enterprise Linux AppStream (v. 9): Red Hat Enterprise Linux BaseOS EUS (v. 10.0): Red Hat Enterprise Linux BaseOS (v. 10): Red Hat Enterprise Linux BaseOS (v. 8): Red Hat Enterprise Linux BaseOS AUS (v. 8.2): Red Hat Enterprise Linux BaseOS AUS (v.8.4): Red Hat Enterprise Linux BaseOS EUS EXTENSION (v.8.4): Red Hat Enterprise Linux BaseOS AUS (v.8.6): Red Hat Enterprise Linux BaseOS E4S (v.8.6): Red Hat Enterprise Linux BaseOS TUS (v.8.6): Red Hat Enterprise Linux BaseOS E4S (v.8.8): Red Hat Enterprise Linux BaseOS TUS (v.8.8): Red Hat Enterprise Linux BaseOS E4S (v.9.0): Red Hat Enterprise Linux BaseOS E4S (v.9.2): Red Hat Enterprise Linux BaseOS EUS (v.9.4): Red Hat Enterprise Linux BaseOS EUS (v.9.6): Red Hat Enterprise Linux BaseOS (v. 9): Red Hat Enterprise Linux CRB (v. 8): Red Hat CodeReady Linux Builder EUS (v.9.4): Red Hat CodeReady Linux Builder EUS (v.9.6): Red Hat Enterprise Linux CodeReady Linux Builder (v. 9): Red Hat OPENJDK ELS 11.0.31: Red Hat AI Inference Server 3.3: Red Hat Build of OpenJDK 17.0.9: Red Hat Ceph Storage 8: Red Hat Discovery 2: Red Hat Hardened Images: Red Hat build of OpenJDK 1.8: Red Hat build of OpenJDK 21: Red Hat build of OpenJDK 25: Red Hat Enterprise Linux 10: Red Hat Enterprise Linux 6: Red Hat Enterprise Linux 8: Red Hat Enterprise Linux 9: Red Hat Enterprise Linux 7:

Exploit Probability

EPSS
0.91%
Percentile
55.10%

EPSS (Exploit Prediction Scoring System) scores estimate the probability that a vulnerability will be exploited in the wild within the next 30 days. The percentile shows you how this score compares to all other vulnerabilities.