# CVE-2024-23903: Non-constant time webhook token comparison in Jenkins GitLab Branch Source Plugin

> Attackers can statistically recover valid webhook tokens due to non-constant time comparison, bypassing authentication checks in the Jenkins GitLab Branch Source Plugin.

- **Severity:** Medium 5.3 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 24 Jan 2024
- **Updated:** 13 Feb 2025
- **Also known as:** GHSA-f67f-2j6r-m4c9

## What is CVE-2024-23903?

CVE-2024-23903 is a medium-severity vulnerability in Jenkins GitLab Branch Source Plugin, published on 24 Jan 2024. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Jenkins GitLab Branch Source Plugin 684.vea_fa_7c1e2fe3 and earlier uses a non-constant time comparison function when checking whether the provided and expected webhook token are equal, potentially allowing attackers to use statistical methods to obtain a valid webhook token.

Weakness: CWE-697 (Incorrect Comparison)

## Which versions are affected by CVE-2024-23903?

2 open source packages ship an affected version, including io.jenkins.plugins:gitlab-branch-source. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `io.jenkins.plugins:gitlab-branch-source` | Maven | All versions | 688.v5fa |
| `io.jenkins.plugins:gitlab-branch-source` | Maven | All versions | 688.v5fa |

Products: Jenkins Github Branch Source.

## How do I fix CVE-2024-23903?

Upgrade io.jenkins.plugins:gitlab-branch-source to 688.v5fa or later.

## Is CVE-2024-23903 being exploited?

There is no known exploitation of CVE-2024-23903 in the wild and no public exploit code.

## Other vulnerabilities in Jenkins GitLab Branch Source Plugin

- [CVE-2024-23901](https://insights.sbomify.com/CVE-2024-23901/): Shared projects are unconditionally discovered by Jenkins GitLab Branch Source Plugin (medium 6.5)
- [CVE-2017-1000091](https://insights.sbomify.com/CVE-2017-1000091/): Jenkins GitHub Branch Source Plugin vulnerable to Cross-Site Request Forgery (medium 6.3)
- [CVE-2026-57285](https://insights.sbomify.com/CVE-2026-57285/): Jenkins GitHub Branch Source Plugin has missing permission check that allows enumerating GitHub Enterprise server URLs (medium 4.3)
- [CVE-2026-42522](https://insights.sbomify.com/CVE-2026-42522/): Jenkins GitHub Branch Source Plugin: Missing permissions check allows attackers to perform a connection test (medium 4.3)
- [CVE-2024-23902](https://insights.sbomify.com/CVE-2024-23902/): CSRF vulnerability in Jenkins GitLab Branch Source Plugin (medium 4.3)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2024-23903 and fix it if it is affected.

What it is: CVE-2024-23903 is a medium-severity vulnerability in Jenkins GitLab Branch Source Plugin, published on 24 Jan 2024. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2024-23903 in the wild and no public exploit code.

Affected packages and fixed versions:
- io.jenkins.plugins:gitlab-branch-source (Maven): affected all versions; fixed in 688.v5fa
- io.jenkins.plugins:gitlab-branch-source (Maven): affected all versions; fixed in 688.v5fa

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2024-23903/ (Markdown: https://insights.sbomify.com/CVE-2024-23903/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2024-23903
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2024-23903
- OSV: https://osv.dev/vulnerability/CVE-2024-23903

---
From sbomify Insights: https://insights.sbomify.com/CVE-2024-23903/
Summaries are generated and may contain mistakes; the official description above is the record.