A flaw was found in libgit2 before version 0.27.3. It has been discovered that an unexpected sign extension in git_delta_apply function in delta.c file may lead to an integer overflow which in turn leads to an out of bound read, allowing to read before the base object. An attacker may use this flaw to leak memory addresses or cause a Denial of Service.
https://lists.debian.org/debian-lts-announce/2022/03/msg00031.html
https://lists.debian.org/debian-lts-announce/2018/08/msg00024.html
https://github.com/libgit2/libgit2/releases/tag/v0.27.3
https://github.com/libgit2/libgit2/commit/c1577110467b701dcbcf9439ac225ea851b47d22
https://github.com/libgit2/libgit2/commit/3f461902dc1072acb8b7607ee65d0a0458ffac2a