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CVE-2026-37977 low CVSS 3.7

Vulnerability in org.keycloak:keycloak-services (CVE-2026-37977)

Summary

Vulnerability in org.keycloak:keycloak-services (CVE-2026-37977). Risk of unauthorized operations or information disclosure. Exploitable via azp. Mitigation: upgrade to 26.6.3 or later.

Original description

The description as published by the source.

A flaw was found in Keycloak. A remote attacker can exploit a Cross-Origin Resource Sharing (CORS) header injection vulnerability in Keycloak's User-Managed Access (UMA) token endpoint. This flaw occurs because the azp claim from a client-supplied JSON Web Token (JWT) is used to set the Access-Control-Allow-Origin header before the JWT signature is validated. When a specially crafted JWT with an attacker-controlled azp value is processed, this value is reflected as the CORS origin, even if the grant is later rejected. This can lead to the exposure of low-sensitivity information from authorization server error responses, weakening origin isolation, but only when a target client is misconfigured with webOrigins: ["*"].

Source: NIST National Vulnerability Database NVD GitHub Advisory

Auto-generated summary

Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.

A vulnerability tracked as CVE-2026-37977 has been found in org.keycloak:keycloak-services.
Attackers can target a specific entry point like azp over the network to misuse the product.
Risk of unauthorized operations or information disclosure. CVSS score: 3.7/10.
What to do: upgrade org.keycloak:keycloak-services to 26.6.3 or later.
If unsure, ask your IT team or search "org.keycloak:keycloak-services CVE-2026-37977" on the vendor's site.

CVE-2026-37977 (org.keycloak:keycloak-services) — CWE-346 / CVSS v3 3.7
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: azp
Patched: 26.6.3 — apply immediately
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.

❓ What is the problem

A vulnerability (CWE-346) exists in org.keycloak:keycloak-services. Attackers reach the vulnerable code path via azp without authentication.

📍 Affected scope

Check the vendor advisory for the affected versions of org.keycloak:keycloak-services. Attack surface: azp.

🔥 Severity

Severity: Low (CVSS 3.7/10). Risk of unauthorized operations or information disclosure.

🔧 How to fix

Update to 26.6.3.

🛡️ Workaround

Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.

🔍 Detection

Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Audit SBOM/dependencies to find affected services.

Response actions

Concrete steps and command examples for SOC/SRE teams to execute in order

  1. 1
    Identify exposure identify 
    Audit SBOM/dependencies for affected components.

    資産台帳・SBOM・依存マニフェストで org.keycloak:keycloak-services を使っているサービスとバージョンを洗い出す。

  2. 2
    Apply patch patch 
    Upgrade org.keycloak:keycloak-services to 26.6.3

    ステージング環境で 26.6.3 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。

  3. 3
    Post-deployment verification verify 
    Confirm patched version is live in production

    パッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。

Affected packages

maven org.keycloak:keycloak-services
[{"type":"ECOSYSTEM","events":[{"introduced":"26.5.0"},{"fixed":"26.6.3"}]}]

References

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