high

CVE-2026-78675

PyPI · GitPython

Summary

GitPython: Arbitrary local file content disclosure via [include] directive in untrusted .gitmodules (SubmoduleConfigParser never disables merge_includes)

Severity
high
CVSS
8.4
EPSS
0.1% (p2)
CWE
CWE-73, CWE-200
Also known as
GHSA-7833-fr7j-v32q
Published
2026-09-08
Updated
2026-09-08

Advisory details

[HIGH] Arbitrary local file content disclosure via [include] directive in untrusted .gitmodules (SubmoduleConfigParser never disables merge_includes)

Reachability

GitConfigParser.__init__ defaults merge_includes=True: any config file it parses has its [include] (and, when a repo= is supplied, [includeIf ...]) directives followed and merged in. The maintainers already recognized this as dangerous for one specific case and fixed it in commit 41ecc6a4 ("Disable merge_includes in config writers"), which passes merge_includes=False when Repo.config_writer() builds its parser (git/repo/base.py).

That fix never touched Submodule._config_parser(). This method builds the parser used for every read of a repo's submodule configuration — repo.submodules, Submodule.iter_items(), Submodule.config() — via SubmoduleConfigParser(fp_module, read_only=read_only), passing neither merge_includes=False nor repo=. The True class default is therefore inherited unchanged, and fp_module here is .gitmodules — the single most attacker-controlled config file in the entire codebase, since it ships verbatim as tracked content inside any cloned repository.

GitConfigParser.read()'s include-path resolution (line 662-680) performs no containment check: osp.isabs(include_path) short-circuits the path join entirely for an absolute path, and a relative path is joined with osp.join(osp.dirname(file_path), include_path) / osp.normpath()'d with no check that the result stays under the repository. `is expanded viaosp.expanduser. The only gate before opening is os.access(include_path, os.R_OK)` — a readability check, not a path restriction.

Once opened, GitConfigParser._read() parses the target file as git-config INI. If the first non-blank/non-comment line is not a [section] header — true of virtually any non-gitconfig file (source code, /etc/passwd, .env files, credential files, logs, JSON/YAML) — it raises configparser.MissingSectionHeaderError(fpname, lineno, line). Python's stdlib formats this exception's str() as "File contains no section headers.\nfile: %r, line: %d\n%r" % (fpname, lineno, line) — it embeds the verbatim content of that file's first line in the exception message. Submodule.iter_items() catches only (IOError, BadName), not configparser.Error, so this exception propagates straight out of the ordinary, read-only repo.submodules call.

Root cause

Parity gap between two config-parser construction sites for the exact same footgun: Repo.config_writer() was hardened against merge_includes in 2023 (41ecc6a4); Submodule._config_parser() — which parses .gitmodules, content that is always attacker-controlled the moment a repository is cloned from an untrusted source — was never given the same treatment. (The submodule write-mode config parser at git/objects/submodule/base.py for .git/modules/<name>/config — a different, locally-generated file — has correctly passed merge_includes=False since 2022, underscoring that the omission for .gitmodules reads looks like an oversight rather than a considered exception.)

Exploit path

  1. Attacker crafts a repository whose .gitmodules contains a legitimate-looking [submodule ...] section plus:
    [include]
    path = /etc/passwd
    (an absolute path bypasses any traversal reasoning entirely; a relative ../../../../etc/passwd-style path works too).
  2. Victim performs the extremely common, entirely read-only operation of enumerating a cloned repo's submodules: list(repo.submodules) (or any for sm in repo.submodules) — no update(), init(), or checkout of any kind required.
  3. SubmoduleConfigParser (inheriting merge_includes=True) follows the [include] directive, opens /etc/passwd, and GitConfigParser._read() raises MissingSectionHeaderError whose message embeds /etc/passwd's first line verbatim.
  4. This exception surfaces wherever the host application observes exceptions from GitPython — CI logs, error pages, exception trackers, or any dependency-scanner/code-review-bot/hosting-platform tool built on repo.submodules — disclosing the targeted file's first line to the attacker (directly, or indirectly via any channel that echoes the error).

Impact

Non-blind local file content disclosure (first line) of any file readable by the victim process, triggered purely by attacker-controlled repository content and one routine, read-only GitPython call. Bounded to one line per triggering file (parsing aborts at the first MissingSectionHeaderError), but that line very often is the secret — .env files (DATABASE_URL=..., API_KEY=...), single-line credential/token files, /etc/passwd's root entry for host fingerprinting. The primitive additionally serves as a generic error-based file-existence oracle for arbitrary host paths. This is materially stronger than the already-fixed, explicitly blind GHSA-cwvm-v4w8-q58c ("Blind local file inclusion", CVSS 4.0, git/refs/symbolic.py ref-name resolution) — that advisory's own writeup states it cannot disclose content; this one does, verbatim, via a different module (git/config.py's include resolution).

Preconditions

Evidence

False-positive check (adversarial re-read)

References

Related advisories

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Sources: CISA KEV (public domain), OSV.dev & GitHub Advisory Database (CC-BY-4.0), FIRST EPSS, NVD/CWE (public domain). Served live from the Stateward advisory database.