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CVE-2026-9793VulnerabilityPublished Updated

CVE-2026-9793: Red Hat build of Keycloak 26.4 · Improper Verification of Cryptographic Signature

Affects Red Hat build of Keycloak 26.4Source CVE Database V5

0

Not known to be exploited · CVSS 5.9 Medium.

Data as of 25 Oct 2026, 19:02 UTC

CVSS 3.1 base score
5.9Medium
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.1% chance of exploitation in 30 days – higher than 5% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 28 May 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 2026-10-25.

What to do

Affected software

ProductAffectedFixed in
Red HatRed Hat build of Keycloak 26.4Affected–Fixed in–
Red HatRed Hat build of Keycloak 26.4Affected–Fixed in–
Red HatRed Hat build of Keycloak 26.4.14Affected–Fixed in–
Red HatRed Hat build of Keycloak 26.6Affected–Fixed in–
Red HatRed Hat build of Keycloak 26.6Affected–Fixed in–
Red HatRed Hat build of Keycloak 26.6.5Affected–Fixed in–

AI-suggested

Currently, Red Hat does not offer an official fix or patch for this vulnerability. The available mitigation is the redirect URI allowlist, which acts as a compensating control to prevent full authorization code or token exfiltration. Red Hat states that other mitigation options do not meet their criteria for ease of use, applicability, or stability. Users should monitor the Red Hat advisory page for any future updates or patches and consider applying compensating controls such as strict redirect URI allowlists.

Description

A flaw was found in Keycloak. When a JSON Web Encryption (JWE) encrypted request object is submitted, Keycloak may incorrectly process unsigned claims if the decrypted content is raw JSON, bypassing the configured signature policy. This allows a remote attacker to submit unauthorized claims, leading to a compromise of data integrity within the OpenID Connect (OIDC) authorization flow. While a redirect URI allowlist acts as a compensating control, this vulnerability violates OIDC Core and Financial-grade API (FAPI) signing requirements.

References

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