CVE-2025-12627 Overview
CVE-2025-12627 affects the user impersonation flow in WSO2 Identity Server. The product fails to properly manage refresh tokens associated with impersonated sessions. An attacker who obtains an access token issued for an impersonated user can use the refresh token grant to mint new access tokens. This extends the attacker's ability to act as the legitimate user beyond the original access token lifetime.
The weakness is categorized as insufficient session expiration [CWE-613]. Exploitation compromises log integrity and traceability because actions continue to appear as originating from the impersonated user rather than the true actor.
Critical Impact
Attackers holding an impersonated user's access token can indefinitely renew authorization via the refresh token grant, masking the true actor in audit logs.
Affected Products
- WSO2 Identity Server (user impersonation flow)
- Refer to WSO2 Security Advisory WSO2-2025-4619 for affected versions
Discovery Timeline
- 2026-08-06 - CVE CVE-2025-12627 published to NVD
- 2026-08-06 - Last updated in NVD database
Technical Details for CVE-2025-12627
Vulnerability Analysis
WSO2 Identity Server supports a user impersonation flow that allows an authorized actor to obtain tokens acting on behalf of another user. The OAuth 2.0 refresh token grant is intended to allow clients to obtain new access tokens without repeated user interaction. In a properly designed impersonation flow, refresh tokens tied to impersonated sessions should be scoped, short-lived, or rejected at the token endpoint to prevent session persistence beyond the initial impersonation window.
The defect exposes an authorization persistence issue: refresh tokens minted during impersonation remain valid and honored by the token endpoint. An adversary who captures an impersonated access token, along with its associated refresh token, can continue requesting fresh tokens.
Root Cause
The root cause is insufficient session expiration [CWE-613] in the impersonation token lifecycle. The token service does not distinguish refresh tokens issued during impersonation from standard user refresh tokens. As a result, revocation and lifetime constraints that should apply to impersonated sessions are not enforced when refresh grant requests are processed.
Attack Vector
Exploitation requires an adjacent network position and high privileges, consistent with an attacker who already possesses a valid impersonated access token. The attacker submits the associated refresh token to the token endpoint using the refresh_token grant type. The server returns a new access token bound to the impersonated user. The attacker repeats this cycle to maintain access. Successful actions are logged under the impersonated user identity, degrading log integrity and forensic traceability.
No verified proof-of-concept code is publicly available. See the WSO2 Security Advisory WSO2-2025-4619 for vendor technical details.
Detection Methods for CVE-2025-12627
Indicators of Compromise
- Repeated grant_type=refresh_token requests to the WSO2 Identity Server token endpoint tied to sessions originally established through the impersonation flow.
- Access tokens issued for impersonated users with lifetimes extending well beyond the expected impersonation window.
- Audit log entries showing activity attributed to a user during periods when the user was not actively authenticated.
Detection Strategies
- Correlate token issuance events with impersonation initiation events and flag refresh grants that occur after the impersonating admin session has ended.
- Parse WSO2 Identity Server audit logs for token endpoint activity and identify tokens carrying impersonation claims that are refreshed multiple times.
- Baseline normal refresh token usage per client and alert on outliers, particularly for service accounts and administrative clients.
Monitoring Recommendations
- Forward WSO2 Identity Server audit and carbon logs to a centralized analytics platform for correlation across authentication, token issuance, and application access events.
- Monitor token endpoint traffic for abnormal refresh_token grant volume or extended token chains associated with a single initial impersonation.
- Review privileged operations performed under user identities and cross-check against known active user sessions to identify masked actor activity.
How to Mitigate CVE-2025-12627
Immediate Actions Required
- Apply the patch or update referenced in WSO2 Security Advisory WSO2-2025-4619 as soon as it is available for your deployment.
- Audit accounts with impersonation privileges and reduce their number to the minimum required for operations.
- Revoke existing refresh tokens tied to impersonated sessions and force reauthentication for affected users.
Patch Information
WSO2 has published guidance in security advisory WSO2-2025-4619. Consult the WSO2 Security Advisory WSO2-2025-4619 for specific affected product versions, WUM update levels, and remediation steps.
Workarounds
- Disable the user impersonation feature in WSO2 Identity Server if it is not required by business workflows.
- Restrict impersonation privileges to a narrow set of accounts and enforce short access token lifetimes for those flows.
- Reject refresh_token grant requests for tokens carrying impersonation claims via a custom token issuance handler until an official fix is applied.
- Enforce network segmentation so the WSO2 token endpoint is only reachable from trusted administrative networks, reducing exposure to adjacent-network attackers.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
