GitHub Enterprise Server CVE-2026-3307

The attacker must hold admin-level access on at least one repository within the same GitHub Enterprise Server instance; this is required for the request to pass the initial authorization check. The target organization must have secret scanning push protection with delegated bypass configured and enabled on the target repository - this is a non-default Advanced Security feature requiring explicit activation. Impact is additionally constrained: only users who already exist and are trusted within the GHES instance can be assigned as bypass reviewers; the attacker cannot introduce arbitrary external accounts. Exploitation is limited to contexts where insider threat actors, compromised admin credentials, or multi-tenant GHES deployments exist. The attack requires deliberate, crafted API manipulation and is not automatable at scale per SSVC assessment.

The official CVSS 4.0 vector (AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:L/VA:N) scores 5.3 (Medium), reflecting network-accessible exploitation with low privilege requirements but limited integrity impact and no confidentiality or availability consequence. EPSS at 0.05% in the 14th percentile signals very low real-world exploitation probability. SSVC corroborates this: exploitation status is none, the attack is non-automatable (requires deliberate crafting of a cross-repository request), and technical impact is only partial. The vulnerability is not listed in CISA KEV. The practical blast radius is narrow - an attacker can only assign users already trusted within the GHES instance as bypass reviewers, not escalate to arbitrary account injection or data exfiltration. This combination of limited impact scope, required repository admin access (PR:L), no known exploitation activity, and no public PoC positions this as a medium-priority patch target rather than an emergency. Organizations with strict push protection policies on sensitive repositories should prioritize patching given the targeted integrity impact to security controls.

An attacker with admin access to a low-sensitivity or compromised repository on a GHES instance constructs an API request to the secret scanning push protection endpoint, placing a legitimate URL for their authorized repository in the path while substituting the target repository's identifier in the owner_id body parameter. The server validates the caller's admin rights against the URL repository, then applies the bypass reviewer change to the target repository. The attacker can then cause a trusted user to appear as an authorized bypass reviewer on a repository they should not influence - potentially weakening push protection oversight on a codebase containing production secrets or credentials.