CVE-2026-102827: simple-git: unsafe-operations plugin bypass via git long-option abbreviation (--receive-p/--exe) -> command execution (residual of CVE-2026-28291)

simple-git’s blockUnsafeOperationsPlugin blocks dangerous git options (–upload-pack/–receive-pack/–exec/…) unless the consumer opts in via unsafe:{allowUnsafePack:true}. Detection (@simple-git/argv-parser detectVulnerableFlags) matches the parsed flag NAME against literal-spelling patterns: /–(upload|receive)-pack/ (requires the literal ‘-pack’) and the string ‘–exec’. But git accepts unambiguous prefix abbreviations of long options, and expandToken (token-expander.ts) returns the LITERAL token as flag.name (it uses the spec only for needsNext, never to canonicalize). So git push --receive-p=<cmd> parses with flag.name=’–receive-p’, which /–(upload|receive)-pack/ does NOT match, yet git expands –receive-p -> –receive-pack and runs (on a local/file remote, locally). The clone side is robust (its ‘–u’ substring rule catches every –upload* abbreviation); the push –receive-* and –exe* abbreviations have no equivalent rule and slip through.

Proof of concept (latest: simple-git 3.36.0, @simple-git/argv-parser 1.1.1, default unsafe plugin ON): Gate vulnerabilityCheck: ‘push –receive-pack=touch…’ -> BLOCKED; ‘push –receive-pa=touch…’ and ‘push –receive-p=touch…’ -> BYPASS (empty vulns); ‘–exec=’ BLOCKED, ‘–exe=’ BYPASS. End-to-end via simpleGit().push(): CONTROL git.push([’../bare’,‘HEAD:refs/heads/c’,’–receive-pack=touch /tmp/pwned_ctrl;’]) -> throws GitPluginError ‘Use of –upload-pack or –receive-pack is not permitted…’; no command runs. BYPASS git.push([’../bare’,‘HEAD:refs/heads/e2e’,’–receive-p=touch /tmp/pwned_e2e;’]) -> NO GitPluginError; /tmp/pwned_e2e CREATED (git executed the injected command); only a later GitError surfaces. Direct git confirms git push ../bare --receive-p='touch X;' HEAD:refs/heads/m and --exe='touch Y;' both execute on a local/path remote.

Impact: any app relying on simple-git’s default unsafe-operations protection while passing attacker-influenced options/args into a git push (local/file remote, or attacker-influenced receive-pack target) can be made to execute arbitrary commands – the exact protection CVE-2026-28291 provided, defeated by an abbreviated spelling. Same class/impact as GHSA-jcxm-m3jx-f287, on the push path.

Remediation: canonicalize git option abbreviations before matching (resolve to the canonical long name via the per-task flag spec in expandToken), or match on the option stem/prefix down to the shortest unambiguous form for push receive-pack/exec (mirroring the clone-side ‘–u’ approach). Also audit –template and -c/config-write detection for the same abbreviation gap.

Credit: anir0y (independent security research).