CVE-2026-18963: Keycloak: Unauthenticated account takeover via reset-credentials flow bypass

Should you act?

Critical and remotely reachable

No known exploitation yet, but it is network-reachable without credentials. This signal is computed from CISA KEV, EPSS and CVSS data; it is not an editorial verdict.

• No confirmed exploitation. It is not in CISA’s KEV catalog and CISA’s SSVC assessment records no known exploitation. That can change quickly after a public write-up; re-check if you are affected.
• EPSS 3.2%, percentile 88: FIRST’s model estimates a 3.2% chance of exploitation activity in the next 30 days, higher than 88% of all scored CVEs (elevated). EPSS is a probability, not a verdict.
• Remotely reachable with no login and no user interaction. If the vulnerable service is exposed to the internet, prioritize it.
• Only applies if your dependency tree includes org.keycloak:keycloak-services (Maven) >= 26.0.0, < 26.4.15, fixed in 26.4.15; org.keycloak:keycloak-services (Maven) >= 26.5.0, < 26.6.6, fixed in 26.6.6; org.keycloak:keycloak-services (Maven) >= 26.7.0, < 26.7.2, fixed in 26.7.2. Check your lockfile, including transitive dependencies.

What it is

A flaw was found in the reset-credentials flow of the keycloak-services component, which is the core engine for identity and access management in Red Hat Build of Keycloak. The issue allows an unauthenticated attacker to force the password reset process for any user without needing to click the required email verification link. This can result in the attacker gaining full control over target user accounts by directly setting new credentials.

From the GitHub advisory

A flaw was found in the reset-credentials flow of the keycloak-services component, which is the core engine for identity and access management in Red Hat Build of Keycloak. The issue allows an unauthenticated attacker to force the password reset process for any user without needing to click the required email verification link. This can result in the attacker gaining full control over target user accounts by directly setting new credentials.

Weakness type: CWE-640.

Product: org.keycloak:keycloak-services (Maven) · Assigned by: redhat · Published: 2026-08-18

Affected and fixed versions

Severity scores

• Attack vector: network (remotely reachable)
• Attack complexity: low
• Privileges required: none (no login)
• User interaction: none
• Scope: unchanged

CVSS measures how bad a flaw is if exploited, not how likely exploitation is. Read it next to the exploitation data below.

Exploitation and urgency

• CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
• CISA SSVC assessment: exploitation none, automatable yes, technical impact total.
• FIRST EPSS (model of 2026-10-21): 3.18% probability of exploitation activity in the next 30 days; percentile 88.

Timeline

• 2026-08-18 — CVE record published by redhat
• 2026-08-18 — GitHub-reviewed advisory GHSA-4gv3-mc9p-5wqc published (critical)
• 2026-09-08 — CVE record last updated

Sources and references

Original sources first. Version and fix details should always be confirmed against the vendor or project advisory.

Vendor and project advisories, patches

1. RHSA-2026:56519 access.redhat.com
2. RHSA-2026:56520 access.redhat.com
3. RHSA-2026:56523 access.redhat.com
4. RHSA-2026:56524 access.redhat.com

Vulnerability records

1. GitHub Advisory GHSA-4gv3-mc9p-5wqc github.com
2. CVE.org record CVE-2026-18963 cve.org
3. NVD entry CVE-2026-18963 nvd.nist.gov

Other references from the CVE record and advisory

1. access.redhat.com access.redhat.com
2. RHBZ#2511595 bugzilla.redhat.com
3. cert-portal.siemens.com cert-portal.siemens.com
4. github.com github.com
5. github.com github.com
6. github.com github.com

Critical Maven advisories · Today’s Security Digest