The binary delta decoder in Mercurial before 3.7.3 allows remote attackers to execute arbitrary code via a (1) clone, (2) push, or (3) pull command, related to (a) a list sizing rounding error and (b) short records.
"https://github.com/pypa/advisory-database/blob/main/vulns/mercurial/PYSEC-2016-29.yaml"