Advisory details:
github_osv / GHSA-5v8v-xvjv-57x7
| Advisory ID | github_osv/GHSA-5v8v-xvjv-57x7 |
| Aliases |
CVE-2026-37977
|
| Summary | Keycloak vulnerable to information disclosure via CORS header injection due to unvalidated JWT azp claim 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: ["*"]`. |
| Status | Published |
| Exploitability | 0.5 |
| Weighted Severity | 3.3 |
| Risk | 1.6 |
| Affected and Fixed Packages | Package Details |
| Introduced and Fixed Package Commit Patches | Package Commit Patches Details |
| CWE-346 | Origin Validation Error |
| System | Score | Found at |
|---|---|---|
| cvssv3.1 | 3.7 | https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/04/GHSA-5v8v-xvjv-57x7/GHSA-5v8v-xvjv-57x7.json |
| generic_textual | LOW |
No EPSS data available for this advisory.
| Patch URL | |
|---|---|
| There are no known patches. | |
| Attack Vector (AV) | Attack Complexity (AC) | Privileges Required (PR) | User Interaction (UI) | Scope (S) | Confidentiality Impact (C) | Integrity Impact (I) | Availability Impact (A) |
|---|---|---|---|---|---|---|---|
network adjacent_network local physical |
low high |
none low high |
none required |
unchanged changed |
high low none |
high low none |
high low none |
Vector: SSVCv2/E:N/A:N/T:P/P:M/B:A/M:M/D:T/2026-04-06T11:55:21Z/
Decision: Track
Source URL: https://github.com/cisagov/vulnrichment/blob/develop/2026/37xxx/CVE-2026-37977.json
Source Advisory: vulnrichment/CVE-2026-37977
[{'Exploitation': 'none'},
{'Automatable': 'no'},
{'Technical Impact': 'partial'},
{'Mission Prevalence': 'minimal'},
{'Public Well-being Impact': 'material'},
{'Mission & Well-being': 'medium'}]