GHSA-fjr4-x663-mwxc

Suggest an improvement
Source
https://github.com/advisories/GHSA-fjr4-x663-mwxc
Import Source
https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/07/GHSA-fjr4-x663-mwxc/GHSA-fjr4-x663-mwxc.json
JSON Data
https://api.test.osv.dev/v1/vulns/GHSA-fjr4-x663-mwxc
Aliases
Downstream
CGA (16)
CLSA (1)
ECHO (1)
MINI (4)
ROOT (1)
Published
2026-07-24T16:41:20Z
Modified
2026-09-29T09:10:33Z
Severity
  • 8.1 (High) CVSS_V3 - CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H CVSS Calculator
Summary
GitPython: Arbitrary file overwrite via git diff --output argument injection in Diffable.diff (key- and value-controlled)
Details

Summary

Diffable.diff() forwards **kwargs straight into diff/diff_tree with no check_unsafe_options guard. Diffable is mixed into Commit, Tree, IndexFile, and Submodule, giving a broad surface. git diff --output=<path> writes real patch content to an attacker-chosen path, enabling arbitrary file overwrite.

Root Cause

diff.py:188-283 builds and runs the diff command with no check_unsafe_options anywhere in the method (grep-confirmed). Additionally diff.py:265 does args.insert(0, other), placing the caller-supplied other ref BEFORE the -- separator, so a value of --output=/path is parsed by git as an option — a value-only control path requiring no kwarg key.

Impact

Overwrite/corrupt any file at process privilege with attacker-chosen path (e.g. ~/.ssh/authorized_keys, configs, lockfiles). Content is real diff/patch bytes (attacker-influenced). Per the skill's rule, controlling WHICH file is overwritten = I:H regardless of content constraints.

Proof of Concept

# Key-control:
commit.diff(other_commit, output='/home/app/.ssh/authorized_keys')   # victim overwritten with diff (105 bytes verified)
# Value-control (attacker controls only the ref string):
commit.diff(other='--output=/home/app/.ssh/authorized_keys')          # 14-byte victim -> 146 bytes of diff-tree output

Attack Chain

  1. Entry (value-control): commit.diff(other=<user ref>) with other = "--output=/home/app/.ssh/authorized_keys". Guard: none in Diffable.diff. Bypass proof: no check_unsafe_options in the method body (grep); other inserted pre--- at diff.py:265.
  2. Sink: git diff-tree <sha> --output=/home/app/.ssh/authorized_keys -r ... -> git opens+truncates the target then writes diff content. Impact: overwrite/corrupt any file at process privilege (attacker chooses the path). Verified argv and victim overwrite live.

Bypass Evidence

Live-verified on HEAD (tag 3.1.53): both key-control (output=) and value-control (other='--output=...') overwrote a victim file with real diff-tree content; argv confirmed ['git','diff-tree','<sha>','--output=/victim','-r',...]. This is the same value-control model GHSA-956x deemed fix-worthy for iter_commits(rev='--output=') — but diff is a distinct, unguarded sink NOT touched by that fix.

Affected Versions

<= 3.1.53

Suggested Fix

Add check_unsafe_options to Diffable.diff (mirroring iter_commits/archive), and/or place --end-of-options before the other ref so it cannot be parsed as an option.

Reported by zx (Jace) — GitHub: @manus-use

Database specific 
{
    "cwe_ids": [
        "CWE-88"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-07-24T16:41:20Z",
    "nvd_published_at": null,
    "severity": "HIGH"
}
References

Affected packages

PyPI / gitpython

Package

Name
gitpython
View open source insights on deps.dev
Purl
pkg:pypi/gitpython

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0 Unknown introduced version / All previous versions are affected
Fixed
3.1.54

Affected versions

0.*
0.1.7
0.2.0-beta1
0.3.0-beta1
0.3.0-beta2
0.3.1-beta2
0.3.2.RC1
0.3.2
0.3.2.1
0.3.3
0.3.4
0.3.5
0.3.6
0.3.7
1.*
1.0.0
1.0.1
1.0.2
2.*
2.0.0
2.0.1
2.0.2
2.0.3
2.0.4
2.0.5
2.0.6
2.0.7
2.0.8
2.0.9.dev0
2.0.9.dev1
2.0.9
2.1.0
2.1.1
2.1.2
2.1.3
2.1.4
2.1.5
2.1.6
2.1.7
2.1.8
2.1.9
2.1.10
2.1.11
2.1.12
2.1.13
2.1.14
2.1.15
3.*
3.0.0
3.0.1
3.0.2
3.0.3
3.0.4
3.0.5
3.0.6
3.0.7
3.0.8
3.0.9
3.1.0
3.1.1
3.1.2
3.1.3
3.1.4
3.1.5
3.1.6
3.1.7
3.1.8
3.1.9
3.1.10
3.1.11
3.1.12
3.1.13
3.1.14
3.1.15
3.1.16
3.1.17
3.1.18
3.1.19
3.1.20
3.1.22
3.1.23
3.1.24
3.1.25
3.1.26
3.1.27
3.1.28
3.1.29
3.1.30
3.1.31
3.1.32
3.1.33
3.1.34
3.1.35
3.1.36
3.1.37
3.1.38
3.1.40
3.1.41
3.1.42
3.1.43
3.1.44
3.1.45
3.1.46
3.1.47
3.1.48
3.1.49
3.1.50
3.1.51
3.1.52
3.1.53

Database specific

last_known_affected_version_range 
"<= 3.1.53"
source 
"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/07/GHSA-fjr4-x663-mwxc/GHSA-fjr4-x663-mwxc.json"