Apache Syncope CVE-2026-77883

Exploitation requires two specific conditions to be met simultaneously. First, the attacker must hold an Apache Syncope administrator account with entitlements specifically covering Derived Schema creation or modification - this is a granular, non-default administrative privilege within Syncope's role-based entitlement model. Second, a separate administrator with User read entitlements must trigger evaluation of the malicious schema by reading a User object that has associated LinkedAccounts or a defined Manager. The vulnerability does not affect deployments where no LinkedAccounts or Manager relationships are defined on User objects. Exploitation is limited to the Syncope internal administrator trust boundary - it is not reachable by end-users or external unauthenticated parties. The attack cannot be automated at scale (SSVC: Automatable: no) and does not cross a scope boundary (CVSS S:U).

The NVD-assigned CVSS 3.1 score of 4.9 (AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:N/A:N) is well-calibrated for this vulnerability. The PR:H metric correctly reflects that exploitation requires an administrator account with specific Derived Schema creation entitlements - a non-trivial access tier in a properly administered IGA deployment. SSVC further confirms Exploitation: none and Automatable: no, meaning there is no evidence of in-the-wild use and the attack cannot be scripted at scale against random targets. EPSS data is not provided but is expected to be low given the high privilege bar. Despite the C:H impact (hashed credentials exposure), the real-world risk is constrained to insider threat scenarios or situations where an admin account is already compromised. The 'Information Disclosure' tag is accurate. No conflicting signals exist between the CVSS vector and the description - both consistently require high privilege and describe confidentiality-only impact. This is not a priority for external perimeter defenses but is meaningful for organizations concerned about insider privilege abuse or least-privilege enforcement within Syncope.

A malicious or compromised Syncope administrator with Derived Schema entitlements creates a new Derived Schema containing a JEXL expression designed to traverse the User object graph and extract LinkedAccount password hashes or Manager credential fields. When any other administrator with User read access subsequently runs a user query or pulls a user record, the server-side JEXL engine evaluates the expression and returns the sensitive fields as part of the schema output. No public proof-of-concept exists at time of analysis.