CVE-2026-33019
libsixel: Integer overflow leads to Out-of-bounds Read in img2sixel
Description
libsixel is a SIXEL encoder/decoder implementation derived from kmiya's sixel. Versions 1.8.7 and prior contain an integer overflow leading to an out-of-bounds heap read in the --crop option handling of img2sixel, where positive coordinates up to INT_MAX are accepted without overflow-safe bounds checking. In sixel_encoder_do_clip(), the expression clip_w + clip_x overflows to a large negative value when clip_x is INT_MAX, causing the bounds guard to be skipped entirely, and the unclamped coordinate is passed through sixel_frame_clip() to clip(), which computes a source pointer far beyond the image buffer and passes it to memmove(). An attacker supplying a specially crafted crop argument with any valid image can trigger an out-of-bounds read in the heap, resulting in a reliable crash and potential information disclosure. This issue has been fixed in version 1.8.7-r1.
INFO
Published Date :
April 14, 2026, 10:16 p.m.
Last Modified :
April 14, 2026, 10:16 p.m.
Remotely Exploit :
No
Source :
[email protected]
Affected Products
The following products are affected by CVE-2026-33019
vulnerability.
Even if cvefeed.io is aware of the exact versions of the
products
that
are
affected, the information is not represented in the table below.
No affected product recoded yet
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS 3.1 | HIGH | [email protected] | ||||
| CVSS 3.1 | HIGH | MITRE-CVE |
Solution
- Update libsixel to version 1.8.7-r1.
- Avoid using the --crop option with large coordinates.
- Validate user-supplied crop coordinates for bounds.
- Sanitize all input used in memory operations.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-33019.
| URL | Resource |
|---|---|
| https://github.com/saitoha/libsixel/releases/tag/v1.8.7-r1 | |
| https://github.com/saitoha/libsixel/security/advisories/GHSA-c854-ffg9-g72c |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-33019 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-33019
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-33019 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-33019 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
New CVE Received by [email protected]
Apr. 14, 2026
Action Type Old Value New Value Added Description libsixel is a SIXEL encoder/decoder implementation derived from kmiya's sixel. Versions 1.8.7 and prior contain an integer overflow leading to an out-of-bounds heap read in the --crop option handling of img2sixel, where positive coordinates up to INT_MAX are accepted without overflow-safe bounds checking. In sixel_encoder_do_clip(), the expression clip_w + clip_x overflows to a large negative value when clip_x is INT_MAX, causing the bounds guard to be skipped entirely, and the unclamped coordinate is passed through sixel_frame_clip() to clip(), which computes a source pointer far beyond the image buffer and passes it to memmove(). An attacker supplying a specially crafted crop argument with any valid image can trigger an out-of-bounds read in the heap, resulting in a reliable crash and potential information disclosure. This issue has been fixed in version 1.8.7-r1. Added CVSS V3.1 AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:H Added CWE CWE-125 Added CWE CWE-190 Added Reference https://github.com/saitoha/libsixel/releases/tag/v1.8.7-r1 Added Reference https://github.com/saitoha/libsixel/security/advisories/GHSA-c854-ffg9-g72c