[RFC PATCH 0/6] Git 3.0: restrict hex object IDs to lowercase only
From: brian m. carlson <hidden>
Date: 2026-07-29 23:32:19
As far as I can tell, Git has always emitted hex object IDs in lowercase, but our object ID parser accepts both uppercase and lowercase. This leads to much software relying on hex object IDs being broken because it doesn't handle uppercase object IDs and this can even lead to security problems when people assume that an object ID has a unique hex form. This series proposes to remove the ability to use uppercase hex in object IDs in Git 3.0. It is RFC simply because it's not clear if there's the desire to do this, although the series should be fully functional. As further evidence of why we should do this, I'll note that there is exactly one testcase in our testsuite that fails due to this change (fixed in the last patch) and it's not clear that it fails intentionally. If we decide not to adopt this series, it would probably be prudent to add some additional tests for the uppercase variant of hex object IDs. brian m. carlson (6): hex: add functionality for lowercase-only hex hex: allow specifying hex type with hex2chr hex: make hex_to_bytes accept kind of hex to use hex: label usages of hex parsing for object IDs object-name: use hexval hex: allow only lowercase object IDs in breaking changes mode Documentation/BreakingChanges.adoc | 5 ++++ builtin/index-pack.c | 2 +- color.c | 2 +- diagnose.c | 2 +- hex-ll.c | 39 ++++++++++++++++++++++++++++-- hex-ll.h | 24 +++++++++++++----- hex.c | 2 +- http-push.c | 5 ++-- mailinfo.c | 2 +- notes.c | 5 ++-- object-file.c | 2 +- object-name.c | 13 +++------- pkt-line.c | 8 +++--- ref-filter.c | 2 +- strbuf.c | 2 +- t/t1503-rev-parse-verify.sh | 5 ++++ t/t5324-split-commit-graph.sh | 4 +-- url.c | 2 +- urlmatch.c | 2 +- 19 files changed, 90 insertions(+), 38 deletions(-)