CVE-2023-6927: A flaw was found in Keycloak

Routine

MEDIUM 4.6WATCHLISTMITIGATEDOWNGRADE

CVE-2023-6927 is a medium-severity flaw (CVSS 4.6) affecting keycloak, single sign-on. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

A flaw was found in Keycloak. This issue may allow an attacker to steal authorization codes or tokens from clients using a wildcard in the JARM response mode "form_post.jwt" which could be used to bypass the security patch implemented to address CVE-2023-6134.

Why this priority

On your watchlist

No fix is published yet: follow the downgrade or mitigation steps.

Risk facts

CVSS score	4.6 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	Low
User interaction	Required
EPSS exploit chance	1.1% (top 34%)
CISA exploited list	No
Weakness	CWE-601
Published	2023-12-18
Last modified	2026-09-22

Publisher (CNA): Red Hat, Inc. · Vendor: redhat

Last updated 2026-09-22 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2023-12-18 23:15 UTCPublished CVE record published
2026-09-22 04:17 UTCUpdated Record last modified

redhat keycloak MITIGATE

Affected: all versions

Fixed in: no fixed release known

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy keycloak || rpm -q keycloak || keycloak --version

No fixed or unaffected release known

Apply the vendor mitigation from the advisory, disable the affected feature, or restrict network access.

redhat single sign-on DOWNGRADE

Affected: 7.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 7.0

1. Check installed version

apt-cache policy single-sign-on || rpm -q single-sign-on || single-sign-on --version

2. No fixed release: DOWNGRADE to a release before 7.0 (Debian / Ubuntu)

apt-cache madison single-sign-on sudo apt install single-sign-on=<VERSION_BEFORE_7.0> sudo apt-mark hold single-sign-on

2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list single-sign-on sudo dnf downgrade single-sign-on-<VERSION_BEFORE_7.0> sudo dnf versionlock add single-sign-on

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2023-6927?

keycloak: mitigate or apply the listed mitigation; single sign-on: downgrade or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2023-6927 being exploited?

CVE-2023-6927 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2023-6927 affect?

CVE-2023-6927 affects keycloak, single sign-on. Severity is medium (CVSS 4.6). A flaw was found in Keycloak. This issue may allow an attacker to steal authorization codes or tokens from clients using a wildcard in the JARM response mode "form_post.jwt" which could be used to bypass the security patch implemented to ad

How urgent is CVE-2023-6927?

Priority 38/100. On your watchlist

Software pages

Keycloak vulnerabilities

Related CVEs

CVE-2023-6563 HIGH 7.7 UPGRADE DOWNGRADE An unconstrained memory consumption vulnerability was discovered in Keycloak
CVE-2023-6291 HIGH 7.1 UPGRADE DOWNGRADE A flaw was found in the redirect_uri validation logic in Keycloak
CVE-2023-6134 MEDIUM 4.6 UPGRADE UPGRADE A flaw was found in Keycloak that prevents certain schemes in redirects, but permits them if a wildcard is app
CVE-2025-8419 MEDIUM 5.3 MITIGATE A vulnerability was found in Keycloak-services
CVE-2025-7365 HIGH 7.1 MITIGATE A flaw was found in Keycloak

References

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