Red Hat Keycloak up to 26.7.3 Login Flow authentication replay

Summaryinfo

A vulnerability has been found in Red Hat Keycloak up to 26.7.3 and classified as critical. Affected by this vulnerability is an unknown functionality of the component Login Flow. Performing a manipulation results in authentication replay. This vulnerability is reported as CVE-2026-90997. The attack is possible to be carried out remotely. No exploit exists. The affected component should be upgraded.

Detailsinfo

A vulnerability, which was classified as critical, was found in Red Hat Keycloak up to 26.7.3. This affects an unknown part of the component Login Flow. The manipulation with an unknown input leads to a authentication replay vulnerability. CWE is classifying the issue as CWE-294. A capture-replay flaw exists when the design of the product makes it possible for a malicious user to sniff network traffic and bypass authentication by replaying it to the server in question to the same effect as the original message (or with minor changes). This is going to have an impact on confidentiality, integrity, and availability. The summary by CVE is:

A flaw was found in Keycloak. When deployed in stateless mode with MySQL or MariaDB, a mismatch in row-count semantics between the database driver and Keycloak's application logic allows an attacker to bypass replay protection. This vulnerability enables an attacker who intercepts single-use security artifacts, such as JWT client assertions, DPoP proofs, or one-time password (TOTP) codes, to replay them. Successful exploitation grants unauthorized access to the token endpoint or login flow.

The advisory is shared at access.redhat.com. This vulnerability is uniquely identified as CVE-2026-90997 since 09/14/2026. The exploitability is told to be easy. It is possible to initiate the attack remotely. No form of authentication is needed for exploitation. Neither technical details nor an exploit are publicly available. The price for an exploit might be around USD $0-$5k at the moment (estimation calculated on 09/17/2026). MITRE ATT&CK project uses the attack technique T1040 for this issue.

Upgrading to version 26.7.4 eliminates this vulnerability.

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Productinfo

Vendor

• Red Hat

Name

• Keycloak

Version

• 26.7.0
• 26.7.1
• 26.7.2
• 26.7.3

License

• open-source

Website

• Vendor: https://www.redhat.com/

CPE 2.3info

• 🔒
• 🔒
• 🔒

CPE 2.2info

• 🔒
• 🔒
• 🔒

CVSSv4info

CVSSv3info

CVSSv2info

Exploitinginfo

Threat Intelligenceinfo

Countermeasuresinfo

Timelineinfo

Sourcesinfo

Entryinfo

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Discussion