CVE-2026-42500 Panic when reading out of bound palette index in golang.org/x/image/bmp
An attacker can cause a denial of service by providing a malformed BMP file with an out-of-range palette index, crashing the application using the Go image library.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-42500?
CVE-2026-42500 is a medium-severity denial of service vulnerability in golang.org/x/image/bmp, published on 29 May 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
Decoding a paletted BMP file with an out-of-range palette index results in a panic when accessing pixels in the invalid image.
Which versions are affected by CVE-2026-42500?
1 open source package ship an affected version, including golang.org/x/image.
| Package | Affected | Fixed in |
|---|---|---|
golang.org/x/image Go | All versions | 0.41.0 |
How do I fix CVE-2026-42500?
Upgrade golang.org/x/image to 0.41.0 or later.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-42500 being exploited?
There is no known exploitation of CVE-2026-42500 in the wild and no public exploit code.
Sources
Also known as CLEANSTART-2026-FA97173, DEBIAN-CVE-2026-42500, GHSA-m6fh-wvw4-4629, GO-2026-5031, MINI-3w5m-3576-rwgw, MINI-3xjc-h726-h3r4 and 28 more.