Summary
GitPython: Incomplete unsafegitrevision_options denylist omits --contents/-S, enabling arbitrary file read via Repo.blame()
Repo.blame() / Repo.blame_incremental() guard forwarded revision options against unsafe_git_revision_options, but that denylist only contains the file-WRITE options --output/-o. git blame also honors --contents <file> and -S <file>, which cause the file's lines to be echoed into the blame result, an arbitrary file READ. Neither option is in the denylist, so a caller-influenced revision value of --contents=<path> passes the guard and leaks file contents. This is a distinct sink-option and impact class (READ) from GHSA-956x-8gvw-wg5v (which addressed the blame --output WRITE), directly analogous to GHSA-539m-9xh6-q6rr (archive READ gap accepted separately from the archive write/exec advisory).
Root Cause
unsafe_git_revision_options = ["--output","-o"] (git/repo/base.py:188). The rev string is passed to _option_candidates([rev], kwargs) and placed BEFORE the -- separator (base.py:841). The canonical name of --contents=... is contents, which is not on the denylist, so no UnsafeOptionError is raised. The trailing -- protects only the pathspec, not the option before the revision.
Proof of Concept
result = repo.blame("--contents=/etc/passwd", "a.txt")
# result rows carry the victim file's line text
Attack Chain
- Entry: app calls
repo.blame(rev, file)with attackerrev="--contents=/etc/passwd"(or kwargcontents="/etc/passwd", or-S). - Check:
Git.check_unsafe_options(_option_candidates([rev,...], kwargs), unsafe_git_revision_options)@ base.py:841. Guard: denylist =["--output","-o"]only. Bypass proof: canonical namecontents∉ denylist → no error. - Sink:
self.git.blame(rev, "--", file, p=True, ...). argv (observed):['git','blame','-p','--contents=<secret>','HEAD','--','a.txt']. - Impact: blame result rows carry the victim file's line text.
Bypass Evidence
Independently reproduced (independent test harness, default allow_unsafe_options=False): blame('--contents=<secret>','a.txt') → guard PASSED; result rows = ['GATE_SECRET_LINE_A','GATE_SECRET_LINE_B']. Control: blame('--output=…') still BLOCKED (guard active on this path). -S kwarg argv also reaches git unguarded.
Affected Versions
GitPython <= 3.1.58 (denylist present verbatim on the latest release tag).
Impact
Arbitrary local file read at the privileges of the host process; the file's line contents appear in the blame result returned to the caller. Pure VALUE control (the caller forwards a user-influenced revision string). Default allow_unsafe_options=False.
CVE-2026-78678 has a CVSS score of 6.5 (Medium). The vector is network-reachable, low privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (3.1.59); upgrading removes the vulnerable code path.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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Prefer an allowlist of blame options; at minimum add --contents/-S (and any other path-taking blame options) to unsafe_git_revision_options, and make the membership rule "the option takes a filesystem path" rather than "the option writes output".
Reported by zx (Jace), GitHub: @manus-use
Frequently Asked Questions
- What is CVE-2026-78678? CVE-2026-78678 is a medium-severity security vulnerability in GitPython (pip), affecting versions <= 3.1.58. It is fixed in 3.1.59.
- How severe is CVE-2026-78678? CVE-2026-78678 has a CVSS score of 6.5 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
- Which versions of GitPython are affected by CVE-2026-78678? GitPython (pip) versions <= 3.1.58 is affected.
- Is there a fix for CVE-2026-78678? Yes. CVE-2026-78678 is fixed in 3.1.59. Upgrade to this version or later.
- Is CVE-2026-78678 exploitable, and should I be worried? Whether CVE-2026-78678 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2026-78678 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2026-78678? Upgrade
GitPythonto 3.1.59 or later.