External risk intelligence

Apache Syncope SRA JWT Forgery Vulnerability

CVE advisorySeverity: CRITICAL (CVSS 9.1)

CVE-2026-87802

Apache Syncope SRA (Security Response Agent) functions as a proxy or gateway for services. Since it is designed to handle OAuth 2.0 authentication and authorization at the edge or as a reverse proxy, it is commonly deployed in network-facing positions to manage, filter, and secure traffic for backend services.

Halo Surface Signal: 4 out of 5 — likely to be public-facing.

External exposure likelihood

Horizon Alert

Summary of the vulnerability and why it matters

This vulnerability affects Apache Syncope, a system used for managing user identities and permissions. It could allow an unauthorized individual to impersonate any user, gaining access to services. The main concern is to confirm if your environment uses the affected technology and is potentially exposed.

Unauthorized users can impersonate others.
Critical systems could be accessed by attackers.
Confirm relevance and assess potential exposure.

Attack Path

How an attacker could exploit the issue

An attacker could forge arbitrary JSON Web Tokens (JWTs) to impersonate any user and gain unauthorized access to services proxied by Apache Syncope's Security Response Agent (SRA). This is possible when SRA is configured for OAuth 2.0, but a JSON Web Key Set (JWKS) Uniform Resource Identifier (URI) is not assigned. By creating a malicious JWT, an attacker could bypass authentication and authorization controls, leading to a compromise of sensitive data and services.

Requires network access and no prior authentication.
Triggered by sending a forged JWT to SRA.
Results in impersonation and full service access.

Live Threat

Current exploitation, exposure, and threat context

When Apache Syncope's SRA is configured for OAuth 2.0 without a JWKS set URI, an attacker could forge arbitrary JSON Web Tokens (JWTs) to impersonate any user identity and permissions. This could lead to unauthorized access to services proxied by SRA.

User identities and permissions.
Forging JWTs when JWKS is unassigned.
Full access to proxied services.

Operational Fix

Recommended remediation, mitigation, and detection steps

The Apache Syncope SRA component, when configured for OAuth 2.0 without a JWKS set URI, presents a critical risk. Application owners and infrastructure teams are likely responsible for managing Apache Syncope deployments. The immediate first step is to identify all instances of Apache Syncope, confirm their external reachability and business criticality, and then coordinate remediation efforts based on assessed risk, potentially involving vendor coordination for upgrades.

Application and Infrastructure teams own this.
Verify SRA OAuth 2.0 and JWKS configuration.
Plan upgrades during the next maintenance window.

Supplementary metadata

CVSS vector

Validate whether this threat affects your internet-facing exposure.

Halo Threat Intelligence helps prioritize remediation with Halo Surface Signal and H/A/L/O context. Start exposure validation with a free external attack surface trial.

Free EASM Trial See How Signal Works

Frequently asked questions

What is Apache Syncope and its SRA component?

Apache Syncope is an open-source platform used by organizations to manage digital identities, roles, and access rights across complex IT environments. Its Security Response Agent (SRA) acts as a gateway or reverse proxy that handles incoming traffic, enforcing authentication and authorization rules before requests reach backend services.

How does CWE-347 relate to CVE-2026-87802?

This vulnerability is classified as CWE-347, which refers to improper verification of cryptographic signatures. In this specific case, the SRA component fails to properly validate the digital signature of incoming JSON Web Tokens (JWTs). Because the signature isn't checked against a trusted source, the system accepts forged tokens as legitimate, allowing unauthorized parties to masquerade as any user.

When does this JWT forgery vulnerability occur?

The flaw is triggered when the SRA is configured to use OAuth 2.0 but lacks a designated JSON Web Key Set (JWKS) URI. Without this URI, the system has no reference to verify the authenticity of incoming tokens. If the SRA is configured with a JWKS URI correctly, this specific forgery path is not triggered.

Do I need to worry if my Syncope SRA is internal?

Halo Surface Signal notes that because SRA functions as a proxy at the network edge, it is frequently placed in internet-facing positions to manage traffic. While external exposure significantly increases the risk of remote abuse, you should evaluate any SRA instance that handles sensitive traffic, as internal attackers could also exploit this trust issue to move laterally through proxied services.

What is the first step to address this CVE?

Start by auditing your environment to locate all Apache Syncope SRA deployments. Confirm whether they are currently utilizing OAuth 2.0 and verify if a JWKS URI has been assigned. Once identified, prioritize upgrading to version 4.0.8 or 4.1.3, as these releases include the necessary cryptographic validation logic to resolve the forgery risk.

References

Written by Nicholas Merritt

Nicholas Merritt is VP of Security Solutions at Halo Security. With more than 25 years across application security, vulnerability prioritization, and offensive security, he helps teams translate threat data into practical exposure validation and remediation focus. He authors Halo Threat Intelligence CVE advisories using Halo Surface Signal and H/A/L/O context to prioritize internet-facing risk.