CVE-2026-112007

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.

References

• https://github.com/schismtracker/schismtracker
• https://github.com/schismtracker/schismtracker/blob/74215ae300b555928332e03152dfcdc898f96ca6/fmt/ult.c#L319-L330
• https://hackmd.io/@haindpwn/schismtracker-ult-sample-count-oob-write
• https://www.vulncheck.com/advisories/schism-tracker-through-20260524-heap-out-of-bounds-write-via-ult-loader