GHSA-w8jc-g24h-crhw

GitPython command wrappers omit unsafe protocol and option checks

Published

2026-10-27

Modified

2026-10-27

Sources

github-advisory

Summary

### Summary GitPython has spent 2022-2026 rolling out two reusable guards method-by-method: `Git.check_unsafe_protocols(url)` (raises `UnsafeProtocolError` for ` ::` remote-helper URLs - CVE-2022-24439) and `Git.check_unsafe_options(...)` (raises `UnsafeOptionError` for denylisted option spellings - CVE-2023-40267, CVE-2026-42215, CVE-2026-67323). Three wrapper methods that build a `git` argv from caller-controlled values still have **neither**: 1. **`Git.ls_remote`** (git/cmd.py:1128-1143) - checks options (:1139-1141) but forwards the URL positional unchecked; no `allow_unsafe_protocols` parameter exists. The same URL through `clone_from` raises `UnsafeProtocolError`. 2. **`Repo.merge_base`** (git/repo/base.py:895-936) - forwards `**kwargs`/`*rev` to `self.git.merge_base` with no guard; guarded sibling `iter_commits` sits 12 lines up. Its exception handler additionally swallows every non-128 `GitCommandError` into `[]`, masking the injection. 3. **`IndexFile.move`** (git/index/base.py:1092-1168) - forwards `**kwargs` to `git mv` twice (:1147, :1167); guarded sibling `remove()` is 23 lines above. Verified unfixed on `main @ a54d159` (2026-09-21), post-dating latest release 3.1.62 (2026-09-07) - all three sites re-verified today. ### Impact **Site 1 (`ls_remote`)** - RCE conditional on the victim git transport policy. The common 'probe first, then clone' pattern (`Git(...).ls_remote(attacker_url)`) with an `ext::sh -c ...` URL executes arbitrary commands when the victim git permits the ext transport: dynamically verified with `protocol.ext.allow=always` (marker executed). git >= 2.38.1 stock config refuses the transport (`fatal: transport 'ext' not allowed`, rc 128) - GitPython adds no defense-in-depth and surfaces a bare `GitCommandError`. Environments on git < 2.38.1 are exposed with stock config - the exact population CVE-2022-24439 was scored against. **Sites 2/3** - latent argument-injection surface: caller kwargs flow 1:1 into the `git` argv before operands and `--` (cmd.py:1850 `opt_args + ext_args`), and `execute_kwargs` (incl. `shell=True`/`env` - the CVE-2023-40267 Windows mechanism) passes through unguarded. Today `git merge-base`/`git mv` expose no exec option, so we claim the missing-guard class (vendor-settled by CVE-2026-67323, which bundled archive/ls_remote/iter_commits/blame in one advisory), not direct RCE. ### Dynamic verification (today; GitPython main @ a54d159, git 2.55.0, Linux) | # | Call | Result | |---|---|---| | T1 | `repo.git.ls_remote('ext::/tmp/gp_touch.sh')`, stock config | git refuses (rc 128); **no `UnsafeProtocolError` from GitPython** | | T1b | same + victim config `protocol.ext.allow=always` | **marker created - arbitrary command executed** | | T2 | `repo.git.ls_remote('.', upload_pack=...)` | blocked by cmd.py:1141 (options-side fixed - protocol-side is the residual gap) | | T3 | `repo.merge_base('main','side', upload_pack=...)` | **not blocked**; argv `git merge-base --upload-pack=... main side`; rc 129 silently converted to `[]` | | T4 | `repo.index.move(['f1','f2'], output=...)` | **not blocked**; option reaches `git mv` (rc 129) | ### Coverage matrix (main @ a54d159) `check_unsafe_protocols`: 7 call sites (`_clone`, `archive`, `set_url`, `create`, `fetch`, `pull`, `push`) - none on `ls_remote`. `check_unsafe_options`: 24 call sites incl. `ls_remote`, `iter_commits`, `IndexFile.remove` - absent on `merge_base` and `move`. ### Precedents (same repo, same guard family) - **CVE-2022-24439 / GHSA-hcpj-qp55-gfph** (critical): `check_unsafe_protocols` on the clone path - Site 1 is the same `ext::` primitive on a sibling API. - **CVE-2023-40267 / GHSA-pr76-5cm5-w9cj** (critical, 'incomplete fix for CVE-2022-24439'): `check_unsafe_options` - unguarded kwargs to argv treated as RCE (`shell=True` on Windows). - **CVE-2026-42215 / GHSA-rpm5-65cw-6hj4** (high, fixed 3.1.47): underscored-spelling bypass - rollout still active in 2026. - **CVE-2026-67323 / GHSA-956x-8gvw-wg5v**

Affected packages

Remediation: Upgrade to 3.2.0 or later.

References

• https://github.com/advisories/GHSA-w8jc-g24h-crhw