Description
MapServer is a system for developing web-based GIS applications. Starting in version 4.2 and prior to version 8.6.1, a heap-buffer-overflow write in MapServer’s SLD (Styled Layer Descriptor) parser lets a remote, unauthenticated attacker crash the MapServer process by sending a crafted SLD with more than 100 Threshold elements inside a ColorMap/Categorize structure (commonly reachable via WMS GetMap with SLD_BODY). Version 8.6.1 patches the issue.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| MapServer | MapServer | >= 4.2, < 8.6.1 | — |
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | mapserver | 8.6.1-1 | — |
| Debian 13 | mapserver | 8.4.0-4+deb13u2 | — |
| Debian 12 | mapserver | 8.0.0-3+deb12u1 | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 26.10 | mapserver | No fix yet | — |
| Ubuntu 26.04 LTS | mapserver | No fix yet | — |
| Ubuntu 25.10 | mapserver | No fix yet | — |
| Ubuntu 24.04 LTS | mapserver | No fix yet | — |
| Ubuntu 22.04 LTS | mapserver | No fix yet | — |
Show 3 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 20.04 LTS | mapserver | No fix yet | — |
| Ubuntu 18.04 LTS | mapserver | No fix yet | — |
| Ubuntu 16.04 LTS | mapserver | No fix yet | — |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | mapserver | 8.6.1-1.1 | openSUSE-SU-2026:10452-1 |
| openSUSE Leap 16.0 | mapserver | 8.6.1-bp160.1.1 | openSUSE-SU-2026:20476-1 |
Advisories 2
- openSUSE-SU-2026:20476-1 Security update for mapserver SUSE / openSUSE Security Updates · Oct 31, 2026
- openSUSE-SU-2026:10452-1 libjavamapscript-8.6.1-1.1 on GA media SUSE / openSUSE Security Updates · Mar 29, 2026