GHSA-3rp5-jjmw-4wv2 GitPython: git-config section-name injection enables arbitrary config directives (core.sshCommand RCE)
SummaryIn GitPython `<= 3.1.52`, the config writer neutralizes only CR, LF, and NUL in configuration **names**, but writes section names into the `[...]` header with no other escaping. A section/subsection name that contains `] [ "` closes the intended header and opens a second same-line section, injecting an arbitrary config directive — with no newline required. Because a submodule **name** is attacker-controlled data (it comes from a repository's `.gitmodules`, or from an application that lets a user name a submodule) and is written verbatim into the parent repository's trusted `.git/config`, an attacker can set `core.sshCommand` (or `alias.*`, `core.pager`, `core.fsmonitor`) and achieve remote code execution on the victim's next git operation. Likely **CWE-74 (Injection)**.This is a distinct variant of the injection addressed by GHSA-mv93-w799-cj2w / GHSA-v87r-6q3f-2j67: those fixed **newline** injection into config values/names (patched in 3.1.50); the `[r\n\x00]` guard added for them does not stop a **same-line** section break inside a name.DetailsThe only guard applied to section/option names before writing is `_assure_config_name_safe`, which uses a regex that matches solely CR/LF/NUL:`git/config.py:75,897-899` (`GitPython 3.1.52`):The name is then serialized into the header with no escaping of `]`, `[`, `"`, space, `=` or `#`:`git/config.py:693`:For submodules the name is wrapped as `submodule "<name>"` (`git/objects/submodule/util.py:39`, `return f'submodule "{name}"'`), which supplies the balancing quote. A submodule named:therefore serializes to the header `[submodule "x"] [core] sshCommand=CMD #"]`. git parses everything after the first `]` on that line as a fresh section, yielding `core.sshCommand=CMD` (the trailing `#"]` is an inline comment). No CR/LF/NUL appears, so `_assure_config_name_safe` never fires.The attacker-controlled name reaches this sink through documented public entry points that write it into the parent repository's `.git/config`:`Repo.create_submodule(name=<untrusted>, ...)` → `Submodule.add` → `git/objects/submodule/base.py:619` `writer.set_value(sm_section(name), "url", url)` — a single call, no hostile remote required.`Repo.clone_from(<hostile url>)` + `repo.submodule_update(init=True)` → `git/objects/submodule/base.py:855` `writer.set_value(sm_section(self.name), "url", self.url)`, where `self.name` is read unvalidated from the cloned repo's `.gitmodules`.Asymmetry: the sibling class is blocked — a newline in a config **value**, e.g. `set_value("core", "editor", "x\n\tsshCommand=CMD")`, raises `ValueError`. The section-**name** bracket payload is not caught by the same guard.PoCSingle self-contained script, run against the pinned release in an ephemeral environment. Non-destructive: the injected value is an inert marker, verified parse-only with `git config --get`; no ssh/fetch/push is run and nothing is executed.Run:Observed output:The benign name yields a single clean `[submodule "docs"]` section; the malicious name yields an injected `core.sshCommand`. Deterministic across runs. The payload must use balanced double-quotes (an unbalanced `"` makes git reject the header); the `submodule "<name>"` wrapper balances them automatically.ImpactArbitrary attacker-controlled write into the victim's repository-local `.git/config`, which git fully trusts. `core.sshCommand` is executed as the ssh transport command on the victim's next ssh git operation (fetch/pull/push), giving remote code execution; other injectable keys (`alias.*`, `core.pager`, `core.fsmonitor`) fire on more common operations. Reachable in default configuration through two realistic paths:an application that constructs a submodule from untrusted input via `Repo.create_submodule(name=...)` (single call); or`Repo.clone_from` of an untrusted repository followed by `submodule_update` — the canonical submodule threat model, where the malicious name is read from the cloned `.gitmodules`.No non-default git settings are required. Primarily a Unix vector: on Windows the `"` in the resulting `.git/modules/<name>` directory name can abort the fresh-clone write branch (the direct config-API and `create_submodule` sinks are unaffected).Recommended fixReject or escape configuration section/subsection/option **names** that contain `]`, `[`, `"`, or leading/trailing whitespace (or apply git's own section-name escaping) in `_assure_config_name_safe` / `write_section`, rather than only CR/LF/NUL. Validating submodule names before they reach `sm_section` would additionally close the clone-driven path.
CVSS v3.1 score: 7