External risk intelligence

Conflibot Command Injection Vulnerability Allows Arbitrary Code Execution

CVE advisorySeverity: CRITICAL (CVSS 9.1)

CVE-2026-55158

This vulnerability exists within a CI/CD build-time automation tool. It is triggered during the internal pull request processing workflow rather than an internet-facing service, appliance, or application endpoint, making it an internal developer-focused build-time component.

OS Command Injection

Halo Surface Signal: 1 out of 5 — much less likely to be public-facing.

External exposure likelihood

Horizon Alert

Summary of the vulnerability and why it matters

A vulnerability in the Conflibot tool could allow attackers to execute arbitrary commands with access to sensitive information, such as repository secrets and tokens. This occurs when a pull request with specially crafted branch names is processed, potentially leading to unauthorized actions like data exfiltration or code changes. The main concern is confirming the relevance and exposure of this tool within your development workflows.

Malicious pull requests can run unauthorized commands.
Protects against secret exfiltration and unauthorized code changes.
Assess tool usage for potential security risks.

Attack Path

How an attacker could exploit the issue

An attacker can initiate a compromise by opening a pull request with a specially crafted branch name. This branch name, when processed by the vulnerable component, is interpreted as commands executed on the build runner. The attacker can leverage this to gain unauthorized access to secrets and tokens, enabling further malicious actions.

Open pull request with malicious branch name.
Workflow interprets branch name as commands.
Arbitrary command execution and token abuse.

Live Threat

Current exploitation, exposure, and threat context

When a pull request is processed in a vulnerable configuration, specially crafted branch names could be interpreted as commands. This could allow for arbitrary command execution on the system processing the pull request.

Repository secrets and tokens are at risk.
Special characters in pull request branch names.
Unauthorized code execution and data exfiltration.

Operational Fix

Recommended remediation, mitigation, and detection steps

This vulnerability affects the Conflibot tool, specifically impacting how pull requests are processed. The primary responsibility for managing this tool likely falls to the platform or CI/CD engineering teams, who would be accountable for its configuration and integration within the development workflow. The initial step is to identify all instances of Conflibot, determine if they are active and processing pull requests from external sources, and then confirm the specific team or individual responsible for its operation to plan remediation.

Platform/CI/CD teams own this issue.
Verify active Conflibot instances and processing.
Plan updates or remove vulnerable instances.

Supplementary metadata

CVSS vector

Validate whether this threat affects your internet-facing exposure.

Halo Threat Intelligence helps prioritize remediation with Halo Surface Signal and H/A/L/O context. Start exposure validation with a free external attack surface trial.

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Frequently asked questions

What is Conflibot?

Conflibot is a development automation tool integrated into software repositories to manage pull requests. It proactively notifies developers if merging a new pull request will cause technical conflicts with other open changes. It typically runs within CI/CD pipelines to streamline code collaboration.

How does CVE-2026-55158 work?

This vulnerability is an instance of CWE-78, or OS Command Injection. The software improperly combines user-supplied branch names into system commands. Because the application fails to separate the data from the command structure, it inadvertently executes malicious shell characters as if they were legitimate instructions.

Can any pull request trigger this bug?

No. The flaw specifically requires the pull request branch name to contain crafted shell metacharacters designed to manipulate command execution. Standard, clean branch names do not trigger the vulnerability. However, because the tool automatically processes inputs, it executes these commands without any manual review or interaction from project maintainers.

Is my repository at risk?

According to Halo Surface Signal, this vulnerability affects an internal build-time component rather than an internet-facing application. Your primary risk involves the automated processing of pull requests from external sources or untrusted contributors, which could allow an attacker to gain unauthorized access to repository secrets or tokens.

What steps should I take to fix this?

First, identify all active instances of Conflibot within your CI/CD workflows. If you are running a version prior to 1.2.1 or 2.0.0, you must update to a patched version immediately. These updates change how the software handles branch names, moving from string interpolation to safer execution methods that prevent shell command injection.

References

Written by Nicholas Merritt

Nicholas Merritt is VP of Security Solutions at Halo Security. With more than 25 years across application security, vulnerability prioritization, and offensive security, he helps teams translate threat data into practical exposure validation and remediation focus. He authors Halo Threat Intelligence CVE advisories using Halo Surface Signal and H/A/L/O context to prioritize internet-facing risk.