Description
FLTK through 1.4.5 contains a stack-based buffer overflow vulnerability in Fl_BMP_Image::load_bmp_() that allows attackers to corrupt stack memory by supplying an oversized BMP colors_used field. Attackers can craft BMP or ICO files with colors_used above 256 to overflow the 768-byte colormap array, causing crashes or potential code execution.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| fltk | fltk | ≤ 1.4.5 | — |
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 | fltk1.3 +1 | No fix yet | — |
| Debian 13 | fltk1.3 +1 | No fix yet | — |
| Debian 12 | fltk1.3 | No fix yet | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 26.10 | fltk1.3 +1 | No fix yet | — |
| Ubuntu 26.04 LTS | fltk1.3 +1 | No fix yet | — |
| Ubuntu 24.04 LTS | fltk1.3 | No fix yet | — |
| Ubuntu 22.04 LTS | fltk1.3 | No fix yet | — |
| Ubuntu 20.04 LTS | fltk1.3 | No fix yet | — |
Show 2 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 18.04 LTS | fltk1.3 | No fix yet | — |
| Ubuntu 16.04 LTS | fltk1.3 | No fix yet | — |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | fltk | 1.3.11-2.1 | openSUSE-SU-2026:12362-1 |
Amazon Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Amazon Linux 2023 | fltk +3 | 1.3.6-1.amzn2023.0.3 | ALAS2023-2026-3459 |
| Amazon Linux 2 | fltk +3 | 1.3.4-1.amzn2.0.3 | ALAS2-2026-4115 |
Azure Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Azure Linux 3 | fltk | No fix yet | — |
Advisories 3
- ALAS2023-2026-3459 Important: fltk security update (Amazon Linux 2023) Amazon Linux Security Center (ALAS) · Nov 12, 2026
- ALAS2-2026-4115 Important: fltk security update (Amazon Linux 2) Amazon Linux Security Center (ALAS) · Nov 12, 2026
- openSUSE-SU-2026:12362-1 fltk-devel-1.3.11-2.1 on GA media SUSE / openSUSE Security Updates · Oct 31, 2026
References
- GitHub Issue #1632 issue-tracking
- https://github.com/fltk/fltk product
- https://github.com/fltk/fltk/commit/3a049d8262dc759cf9737339420e8457e24c0cb1 patch
- https://github.com/fltk/fltk/blob/release-1.4.5/src/Fl_BMP_Image.cxx#L255-L265 technical-description
- https://hackmd.io/@haindpwn/fltk-bmp-image-stack-heap-overflow third-party-advisory
- VulnCheck Advisory: FLTK through 1.4.5 Stack Buffer Overflow via Fl_BMP_Image colors_used Field third-party-advisory