CVE-2026-87819

GitPython before 3.1.60 contains a regular expression denial of service vulnerability in Actor.name_email_regex that processes commit author and committer fields. Attackers can craft a commit object with a malformed author field containing an unterminated angle bracket to cause quadratic backtracking, exhausting CPU resources for over two minutes per commit access.

Summary

GitPython's Actor.name_email_regex regular expression (git/util.py, line 863) is vulnerable to catastrophic backtracking (ReDoS — Regular Expression Denial of Service). When GitPython parses the author or committer header of a git commit object that contains a long string with an unterminated < (no matching >), the Python regex engine enters quadratic backtracking, causing complete single-threaded CPU exhaustion proportional to the square of the input length.

A single crafted commit object can block any GitPython API call that reads .author or .committer for over two minutes per invocation, enabling denial of service against CI runners, code-hosting backends, repository-scanning pipelines, or any service that processes commits from third-party or untrusted repositories.

Details

Vulnerable file and line:

git/util.py, line 863:

name_email_regex = re.compile(r"(.*) <(.*?)>")

This regex is evaluated inside Actor._from_string() (line 909) every time GitPython resolves a commit's .author or .committer property.

Full call chain — from public API to vulnerable sink:

commit.author # any ordinary GitPython API call └── git/objects/commit.py:917 Commit._deserialize() └── git/objects/util.py:341 parse_actor_and_date(author_line) └── git/util.py:909 Actor._from_string(string) └── Actor.name_email_regex.search(string) ← VULNERABLE

author_line is decoded directly from the raw bytes of the git commit object with no length limit, character restriction, or timeout applied at any point before reaching the regex engine. The same chain is triggered by:

• commit.author
• commit.committer
• repo.iter_commits()
• repo.blame()
• Any web service / CI tool that displays or processes commit metadata

Why this pattern backtracks catastrophically:

The pattern (.*) <(.*?)> contains an unbounded greedy group (.*) followed by a literal space and <. When the input is a long string that contains < but no closing >, the regex engine must try every possible split position for the greedy group — O(n²) candidate positions for a string of length n — each of which then drives the inner lazy group into further sub-match attempts. This is the well-documented "catastrophic backtracking" failure mode for this family of patterns.

Empirically measured scaling (tested against GitPython 3.1.59, commit 52a6cba):

| Author field length (bytes) | Time to resolve .author | |-----------------------------|--------------------------| | 1,000 | 0.0035 s | | 5,000 | 0.084 s | | 10,000 | 0.341 s | | 20,000 | 1.525 s | | 40,000 | 5.963 s | | 60,000 | 13.360 s | | 80,000 | 23.871 s | | 200,000 | 150.488 s |

Each doubling of input size roughly quadruples processing time (e.g. 40,000 → 80,000 bytes: 5.96 s → 23.87 s ≈ 4.0×), confirming O(n²) growth. Git itself imposes no practical size limit on author name fields in the object format.

How the malicious object reaches a victim:

The PoC creates the commit object as a correctly SHA-1-hashed, zlib-compressed git loose object written directly into .git/objects/. git cat-file -t <sha> confirms it is a valid commit type and git's own read-side tools display it without error. Only git's write-side tooling (git commit --author, git update-index, explicit git fsck) applies the sanity checks that would reject a malformed author line. Delivery paths that bypass those checks include:

• A git server with receive.fsckObjects = false (common in self-hosted deployments)
• A .git directory shipped as a tarball, backup, or zip archive
• A git bundle file
• Any automated mirror or import tool that operates at the object level

PoC

Environment used for testing:

• GitPython 3.1.59, installed in editable mode from source (no code modifications)
• Python 3.12.3, git 2.43.0, Ubuntu 24.04

**Script 1 — craft the malicious repository…

Duplicate Advisory

This advisory has been withdrawn because it is a duplicate of GHSA-g5vv-9gxw-82hx. This link is maintained to preserve external references.

Original Description

GitPython before 3.1.60 contains a regular expression denial of service vulnerability in Actor.name_email_regex that processes commit author and committer fields. Attackers can craft a commit object with a malformed author field containing an unterminated angle bracket to cause quadratic backtracking, exhausting CPU resources for over two minutes per commit access.

**GitPython*is a python library used to interact with Git repositories.GitPython provides object model read and write access to your git repository. Access repository information conveniently, alter the index directly, handle remotes, or go down to low-level object database access with big-files support.With the new object database abstraction added in 0.3, its even possible to implement your own storage mechanisms, the currently available implementations are 'cgit' and pure python, which is the default.Documentation The latest documentation can be found here: As this version of GitPython depends on GitDB, which in turn needs smmap to work, installation is a bit more involved if you do a manual installation, instead of using pip.

Security Fix(es):

GitPython before 3.1.60 fails to properly validate the git directory location, allowing attackers to impersonate the git directory using tracked files like gitdir, commondir, and HEAD. Attackers can execute arbitrary code by placing a malicious pre-commit hook in the tracked hooks directory that executes when a victim calls index.commit() on a cloned or opened repository.(CVE-2026-87817)

GitPython 3.1.59 fails to restrict the --no-index option in the high-level diff API, allowing attackers to read arbitrary filesystem paths as repository operands. Attackers can combine --no-index with -I/--ignore-matching-lines to create a content-dependent Boolean oracle, repeatedly querying local files to recover single-line secrets through distinguishable success or error responses.(CVE-2026-87818)

GitPython before 3.1.60 contains a regular expression denial of service vulnerability in Actor.name_email_regex that processes commit author and committer fields. Attackers can craft a commit object with a malformed author field containing an unterminated angle bracket to cause quadratic backtracking, exhausting CPU resources for over two minutes per commit access.(CVE-2026-87819)

**GitPython*is a python library used to interact with Git repositories.GitPython provides object model read and write access to your git repository. Access repository information conveniently, alter the index directly, handle remotes, or go down to low-level object database access with big-files support.With the new object database abstraction added in 0.3, its even possible to implement your own storage mechanisms, the currently available implementations are 'cgit' and pure python, which is the default.Documentation The latest documentation can be found here: As this version of GitPython depends on GitDB, which in turn needs smmap to work, installation is a bit more involved if you do a manual installation, instead of using pip.

Security Fix(es):

GitPython before 3.1.60 fails to properly validate the git directory location, allowing attackers to impersonate the git directory using tracked files like gitdir, commondir, and HEAD. Attackers can execute arbitrary code by placing a malicious pre-commit hook in the tracked hooks directory that executes when a victim calls index.commit() on a cloned or opened repository.(CVE-2026-87817)

GitPython 3.1.59 fails to restrict the --no-index option in the high-level diff API, allowing attackers to read arbitrary filesystem paths as repository operands. Attackers can combine --no-index with -I/--ignore-matching-lines to create a content-dependent Boolean oracle, repeatedly querying local files to recover single-line secrets through distinguishable success or error responses.(CVE-2026-87818)

GitPython before 3.1.60 contains a regular expression denial of service vulnerability in Actor.name_email_regex that processes commit author and committer fields. Attackers can craft a commit object with a malformed author field containing an unterminated angle bracket to cause quadratic backtracking, exhausting CPU resources for over two minutes per commit access.(CVE-2026-87819)

**GitPython*is a python library used to interact with Git repositories.GitPython provides object model read and write access to your git repository. Access repository information conveniently, alter the index directly, handle remotes, or go down to low-level object database access with big-files support.With the new object database abstraction added in 0.3, its even possible to implement your own storage mechanisms, the currently available implementations are 'cgit' and pure python, which is the default.Documentation The latest documentation can be found here: As this version of GitPython depends on GitDB, which in turn needs smmap to work, installation is a bit more involved if you do a manual installation, instead of using pip.

Security Fix(es):

GitPython before 3.1.60 fails to properly validate the git directory location, allowing attackers to impersonate the git directory using tracked files like gitdir, commondir, and HEAD. Attackers can execute arbitrary code by placing a malicious pre-commit hook in the tracked hooks directory that executes when a victim calls index.commit() on a cloned or opened repository.(CVE-2026-87817)

GitPython 3.1.59 fails to restrict the --no-index option in the high-level diff API, allowing attackers to read arbitrary filesystem paths as repository operands. Attackers can combine --no-index with -I/--ignore-matching-lines to create a content-dependent Boolean oracle, repeatedly querying local files to recover single-line secrets through distinguishable success or error responses.(CVE-2026-87818)

GitPython before 3.1.60 contains a regular expression denial of service vulnerability in Actor.name_email_regex that processes commit author and committer fields. Attackers can craft a commit object with a malformed author field containing an unterminated angle bracket to cause quadratic backtracking, exhausting CPU resources for over two minutes per commit access.(CVE-2026-87819)

GitPython before 3.1.60 contains a regular expression denial of service vulnerability in Actor.name_email_regex that processes commit author and committer fields. Attackers can craft a commit object with a malformed author field containing an unterminated angle bracket to cause quadratic backtracking, exhausting CPU resources for over two minutes per commit access.

GitPython before 3.1.60 contains a regular expression denial of service vulnerability in Actor.name_email_regex that processes commit author and committer fields. Attackers can craft a commit object with a malformed author field containing an unterminated angle bracket to cause quadratic backtracking, exhausting CPU resources for over two minutes per commit access.

TuxCare rebuilt gitpython to address 3 CVEs. Fixed in 3.1.31.post14+tuxcare.

Denial of Service via catastrophic backtracking (ReDoS) in Actor.name_email_regex — commit author/committer field parsing Repository content can impersonate the git directory, leading to arbitrary code execution Residual of GHSA-hmq2-w58f-27jc: the fix validates the .gitmodules name but the sibling path field still reaches os.makedirs() unguarded, although GitPython already owns the containment guard

This update for python-GitPython fixes the following issues:

• CVE-2026-67322: environment-variable exfiltration in Repo.clone_from() URL via os.path.expandvars() (bsc#1273357).
• CVE-2026-67323: unguarded Git options passed as keyword arguments in Repo.archive() and git.ls_remote() allow for command injection (bsc#1273358).
• CVE-2026-67325: incomplete command injection blocklist fails to account for git's long-option prefix abbreviation feature and allows for bypass (bsc#1273359).
• CVE-2026-67326: failure to validate newline characters in the section parameter of config_writer() can lead to RCE via core.hooksPath (bsc#1273364).
• CVE-2026-69097: failure to properly escape section names in Git config files allows for injection of arbitrary configuration directives through malicious submodule names and can lead to RCE (bsc#1273414).
• CVE-2026-73619: incomplete denylist in the unsafe_git_archive_options guard that omits --add-file and --add- virtual-file options can lead to arbitrary file reads (bsc#1275755).
• CVE-2026-73620: failure to guard Git option forwarding in IndexFile.checkout() and TagReference.create() can lead to arbitrary file reads and writes (bsc#1275756).
• CVE-2026-73621: argument injection in the Commit.count() method allows for destruction/blanking of arbitrary files (bsc#1275757).
• CVE-2026-73622: failure to disable environment variable expansion in Remote.create() and Submodule.add() URL handling allows for secret exfiltration via URLs containing variable references (bsc#1275751).
• CVE-2026-73623: incomplete denylist in unsafe_git_clone_options that omits --template allows for arbitrary command execution (bsc#1275752).
• CVE-2026-73624: Diffable.diff method fails to validate git options passed through kwargs, which can lead to arbitrary file writes (bsc#1275753).
• CVE-2026-73625: check_unsafe_options guard bypass via smuggling of git options inside single-character kwarg values can lead to arbitrary code execution (bsc#1275754).
• CVE-2026-76217: failure to validate options passed to git rm and git checkout commands in IndexFile.remove() and Head.checkout() can lead to arbitrary file reads (bsc#1275745).
• CVE-2026-76218: unguarded git option forwarding in Repo.init allows for arbitrary command execution (bsc#1275746).
• CVE-2026-76219: unguarded git read-tree option forwarding in IndexFile.from_tree/reset/merge_tree can lead to arbitrary file overwrites (bsc#1275747).
• CVE-2026-76220: check_unsafe_options guard can be bypassed by combining a single-character kwarg with split_single_char_options=False, which can lead to arbitrary OS command injection (bsc#1275748).
• CVE-2026-76221: config-name injection in the option-name validator can lead to remote code execution (bsc#1275749).
• CVE-2026-76222: failure to validate submodule names from .gitmodules files allows creation of Git repositories at arbitrary filesystem paths outside the intended clone directory (bsc#1275750).
• CVE-2026-78675: failure to disable merge_includes when parsing .gitmodules can lead to discloseure of local file contents when arbitrary file paths are included via [include] directives (bsc#1276434).
• CVE-2026-78676: failure to safely re-serialize multi-line git-config values during write operations can corrupt dormant quoted values into live injected directives (bsc#1276433).
• CVE-2026-78677: omission of --separate-git-dir from unsafe_git_clone_options allows for creation of arbitrary git directories outside the intended clone destination (bsc#1276432).
• CVE-2026-78678: incomplete denylist in the unsafe_git_revision_options guard that omits --contents and -S options allows for reading of arbitrary files when these options to are passed to Repo.blame() (bsc#1276431).
• CVE-2026-78679: positional reference parameter can bypass an unsafe option guard and allows for arbitrary file read via…

This update for python-GitPython fixes the following issues:

• CVE-2026-87817: failure to properly validade the git directory location allows attackers to impersonate the git directory using tracked files and execute arbitrary code by placing pre-commit hooks in the tracked hooks directory (bsc#1279905).
• CVE-2026-87818: failure to restrict the --no-index option in the high-level diff API allows attackers to read arbitrary filesystem paths as repository operands and create content-dependent Boolean oracles (bsc#1279906).
• CVE-2026-87819: quadratic backtracking in the Actor.name_email_regex regular expression allows attackers to cause CPU exhaustion and a DoS via a commit with a malformed author field (bsc#1279907).