Loom for AWS CVE-2026-103956

Requires a Loom for AWS deployment (< 1.6.1) running with NO identity provider configured (no Cognito/OIDC IdP). In that mode the local-dev authentication bypass auto-activated for every request - including unauthenticated ones - silently granting super-admin, so no credentials, user interaction, or special payload are needed against such an instance. The decisive LIMITING factor is this configuration: deployments that have an IdP configured are not exploitable via this path, which is why the realistic exposure is confined to IdP-less (often dev, test, or hastily-deployed production) instances rather than every install. The fix makes the bypass fail closed with 401 unless an explicit LOOM_ALLOW_UNAUTHENTICATED_LOCAL_DEV opt-in plus a loopback client are present.

All severity signals point one direction but are conditional. The CVSS 4.0 vector (AV:N/AC:L/AT:N/PR:N/UI:N, all impacts High) yields a 10.0, consistent with CWE-306 missing authentication: a remote, unauthenticated attacker gains super-admin over the agent control plane. However, the single most important qualifier is in the description - exploitation only applies 'in a deployment where no identity provider is configured.' The vendor release notes confirm this was a no-Cognito/no-IdP local-dev bypass that silently activated for ANY request, so any production instance stood up without an IdP is fully exposed, while instances with a configured IdP are not reachable this way. No EPSS score, no CISA KEV listing, and no public POC were provided in the input, so there is no evidence of active exploitation or automated weaponization - the 10.0 reflects worst-case impact, not observed in-the-wild activity. Net: this is a genuine high priority for any IdP-less deployment (credential theft plus IAM policy rewrite enables lateral movement into the AWS account), but the real-world blast radius is gated by that configuration condition rather than being universally exploitable. Missing data to note explicitly: EPSS/KEV/POC status absent from input, so exploitation likelihood cannot be quantified.

A remote attacker locates a Loom for AWS instance (< 1.6.1) deployed without any identity provider and sends an ordinary request to the application API; the auth dependency's local-dev bypass treats it as super-admin. The attacker then reads stored integration credentials, registers attacker-controlled tool servers, and rewrites the IAM role policies attached to managed agent roles to escalate within the AWS account. No public exploit code was identified at time of analysis, though the flaw requires no special tooling to trigger.