CVE-2022-27046

What it actually does

The vulnerability is a heap use-after-free in libsixel/src/dither.c at line 388, which can lead to memory corruption when processing specially crafted SIXEL image data.

Why it matters to the business

Applications using this library to handle images may crash or allow remote code execution, potentially compromising systems that process untrusted graphics files across many downstream dependents.

How an attack unfolds

An attacker supplies a malicious SIXEL-encoded image file to an application linked against the vulnerable library. When the dithering function processes it, the use-after-free is triggered, allowing manipulation of freed memory for code execution.

How to fix it

Upgrade to a version of libsixel newer than 1.8.6 when a fix becomes available, or apply any vendor-supplied patches. Disable SIXEL image processing for untrusted inputs until mitigated.

How to confirm the fix worked

Verify the installed library version is not 1.8.6 and test image processing workflows with sample SIXEL files for absence of crashes or memory errors.

Typical attack path

1. Craft malicious SIXEL image exploiting the UAF in dither.c
2. Deliver image to target application via network or file
3. Trigger processing of the image by the vulnerable library
4. Achieve memory corruption and potential code execution

How to detect it

Monitor application logs and crash reports for anomalies during SIXEL image handling; examine memory dumps or sanitizer outputs for use-after-free patterns in dither processing.

What your security team should do

• Prioritize updating libsixel in all affected products due to public exploit availability
• Restrict or sandbox processing of SIXEL files from untrusted sources
• Review and inventory all applications depending on this library given its ecosystem prevalence