How severe is CVE-2026-3872?

CVE-2026-3872 has a CVSS 3.x base score of 7.3, rated high severity. It is exploitable over network with low attack complexity, requires low privileges and user interaction. Impact on confidentiality is high, integrity high, and availability none.

Is CVE-2026-3872 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (35th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-3872?

CVE-2026-3872 primarily affects Redhat Build Of Keycloak. In total, 5 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2026-3872?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

Does CVE-2026-3872 have an EU (EUVD) identifier?

Yes. CVE-2026-3872 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-18206.

When was CVE-2026-3872 published?

CVE-2026-3872 was published on 2026-04-02 and last updated on 2026-06-30.

CVE-2026-3872

CVE-2026-3872 is a high-severity vulnerability in Redhat Build Of Keycloak with a CVSS 3.x base score of 7.3. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-601.

Key facts

Severity: High (CVSS 3.x base score 7.3)
EPSS exploit prediction: 0% (35th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-18206
Weakness: CWE-601
Affected product: Redhat Build Of Keycloak
Published: 2026-04-02
Last modified: 2026-06-30

Description

A flaw was found in Keycloak. This issue allows an attacker, who controls another path on the same web server, to bypass the allowed path in redirect Uniform Resource Identifiers (URIs) that use a wildcard. A successful attack may lead to the theft of an access token, resulting in information disclosure.

Frequently asked questions

What is CVE-2026-3872?: A flaw was found in Keycloak. This issue allows an attacker, who controls another path on the same web server, to bypass the allowed path in redirect Uniform Resource Identifiers (URIs) that use a wildcard. A successful attack may lead to the theft of an access token, resulting in information disclosure.
How severe is CVE-2026-3872?: CVE-2026-3872 has a CVSS 3.x base score of 7.3, rated high severity. It is exploitable over network with low attack complexity, requires low privileges and user interaction. Impact on confidentiality is high, integrity high, and availability none.
Is CVE-2026-3872 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (35th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-3872?: CVE-2026-3872 primarily affects Redhat Build Of Keycloak. In total, 5 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2026-3872?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
Does CVE-2026-3872 have an EU (EUVD) identifier?: Yes. CVE-2026-3872 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-18206.
When was CVE-2026-3872 published?: CVE-2026-3872 was published on 2026-04-02 and last updated on 2026-06-30.

References

Affected products (5)

cpe:2.3:a:redhat:build_of_keycloak:-:*:*:*:text-only:*:*:*
cpe:2.3:a:redhat:build_of_keycloak:26.2:*:*:*:text-only:*:*:*
cpe:2.3:a:redhat:build_of_keycloak:26.2.15:*:*:*:text-only:*:*:*
cpe:2.3:a:redhat:build_of_keycloak:26.4:*:*:*:text-only:*:*:*
cpe:2.3:a:redhat:build_of_keycloak:26.4.11:*:*:*:text-only:*:*:*

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Other CWE-601 (Open Redirect) vulnerabilities

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CVE-2025-55031 — Critical (CVSS 9.8): Malicious pages could use Firefox for iOS to pass FIDO: links to the OS and trigger the hybrid passkey transport. An…
CVE-2024-22891 — Critical (CVSS 9.8): Nteract v.0.28.0 was discovered to contain a remote code execution (RCE) vulnerability via the Markdown link.

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