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CVE-2026-55158

critical · CVSS 9.1Published 9/15/2026 at 03:17 PMCWE-78

Conflibot warns in advance when merging a pull request will cause conflicts in other open pull requests. Prior to 1.2.1, src/index.ts builds…

Conflibot warns in advance when merging a pull request will cause conflicts in other open pull requests. Prior to 1.2.1, src/index.ts builds git checkout, git merge, and git format-patch commands by interpolating the attacker-controlled pull request head.ref value into strings passed to exec. In the documented pull_request_target configuration, an attacker can open a pull request, including from a fork, whose branch name contains shell metacharacters, and the workflow automatically interprets those characters as commands without maintainer interaction. The commands execute on a runner with base-repository secrets and a write-scoped GITHUB_TOKEN, allowing arbitrary command execution, secret or token exfiltration, unauthorized pushes, and other token abuse. The fixed implementations in src/index.ts and src/conflibot.ts use execFile or spawn argument arrays, and the v2 line also uses numeric pull-request refs rather than branch names. This issue is fixed in versions 1.2.1 and 2.0.0.

Why it matters

Internet-facing
Not identified as a common internet-facing category
Exploitation likelihood
high
  • Remotely exploitable over the network — no physical or local access required
  • Low attack complexity — no special conditions needed to exploit
  • No authentication required
  • No user interaction needed — can be exploited automatically
Recommended mitigation

Apply the vendor patch as soon as it's available or already released.

This analysis is generated from structured CVSS vector data, CISA KEV cross-referencing, and vendor/product category rules — not a manual expert review. Treat it as a starting point, not a substitute for your own assessment.

CVSS Vector Breakdown

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
Attack Vector
Network
Complexity
Low
Privileges Req.
None
User Interaction
None

EU Vulnerability Database (ENISA)

EUVD ID
EUVD-2026-78769
View on EUVD

EUVD is ENISA's EU vulnerability database, still in beta. EPSS is a probabilistic exploitation-likelihood score, not a certainty.

View official CVE record

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