Description
Schism Tracker through 20260524 contains a heap out-of-bounds write vulnerability in fmt_ult_load_song() in fmt/ult.c that fails to clamp the one-byte sample count to MAX_SAMPLES. Attackers can supply a crafted .ult module that overwrites the instruments pointer array, causing csf_destroy() to free attacker-chosen pointers and crash the application.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| schismtracker | Schism Tracker | ≤ 20260524 | — |
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 | schism | 2:20261102-1 | — |
| Debian 13 | schism | No fix yet | — |
| Debian 12 | schism | No fix yet | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 26.10 | schism | No fix yet | — |
| Ubuntu 26.04 LTS | schism | No fix yet | — |
| Ubuntu 24.04 LTS | schism | No fix yet | — |
| Ubuntu 22.04 LTS | schism | No fix yet | — |
| Ubuntu 20.04 LTS | schism | No fix yet | — |
Show 2 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 18.04 LTS | schism | No fix yet | — |
| Ubuntu 16.04 LTS | schism | No fix yet | — |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | schismtracker | 20261102-1.1 | openSUSE-SU-2026:12410-1 |
Advisories 1
- openSUSE-SU-2026:12410-1 schismtracker-20261102-1.1 on GA media SUSE / openSUSE Security Updates · Nov 4, 2026
References
- https://hackmd.io/@haindpwn/schismtracker-ult-sample-count-oob-write technical-description exploit
- https://github.com/schismtracker/schismtracker/blob/74215ae300b555928332e03152dfcdc898f96ca6/fmt/ult.c#L319-L330 technical-description
- https://github.com/schismtracker/schismtracker product
- VulnCheck Advisory: Schism Tracker through 20260524 Heap Out-of-Bounds Write via ULT Loader third-party-advisory