CVE-2026-33020

Published: Apr 15, 2026 Last Modified: Apr 15, 2026

ExploitDB:

Other exploit source:

Google Dorks:

HIGH 7,1

Source: [email protected]

Attack Vector: local

Attack Complexity: low

Privileges Required: none

User Interaction: required

Scope: unchanged

Confidentiality: none

Integrity: high

Availability: high

Description

AI Translation Available

libsixel is a SIXEL encoder/decoder implementation derived from kmiya's sixel. Versions 1.8.7 and prior contain an integer overflow which leads to a heap buffer overflow via sixel_frame_convert_to_rgb888() in frame.c, where allocation size and pointer offset computations for palettised images (PAL1, PAL2, PAL4) are performed using int arithmetic before casting to size_t. For images whose pixel count exceeds INT_MAX / 4, the overflow produces an undersized heap allocation for the conversion buffer and a negative pointer offset for the normalization sub-buffer, after which sixel_helper_normalize_pixelformat() writes the full image data starting from the invalid pointer, causing massive heap corruption confirmed by ASAN. An attacker providing a specially crafted large palettised PNG can corrupt the heap of the victim process, resulting in a reliable crash and potential arbitrary code execution.
This issue has been fixed in version 1.8.7-r1.

EPSS (Exploit Prediction Scoring System)

Trend Analysis

EPSS (Exploit Prediction Scoring System)

Prevede la probabilità di sfruttamento basata su intelligence sulle minacce e sulle caratteristiche della vulnerabilità.

EPSS Score

0,0002

Percentile

0,0th

Updated

EPSS Score Trend (Last 2 Days)

122

Heap-based Buffer Overflow

Draft

Abstraction: Variant Structure: Simple

Common Consequences

Security Scopes Affected:

Availability Integrity Confidentiality Access Control Other

Potential Impacts:

Dos: Crash, Exit, Or Restart Dos: Resource Consumption (Cpu) Dos: Resource Consumption (Memory) Execute Unauthorized Code Or Commands Bypass Protection Mechanism Modify Memory Other

Applicable Platforms

Languages: C, C++, Memory-Unsafe

Likelihood of Exploit: High

View CWE Details

190

Integer Overflow or Wraparound

Stable

Abstraction: Base Structure: Simple

Common Consequences

Security Scopes Affected:

Availability Integrity Confidentiality Access Control Other

Potential Impacts:

Dos: Crash, Exit, Or Restart Dos: Resource Consumption (Memory) Dos: Instability Modify Memory Execute Unauthorized Code Or Commands Bypass Protection Mechanism Alter Execution Logic Dos: Resource Consumption (Cpu)