AshGraphql EUVD-2026-68285

The target application must run AshGraphql versions 0.27.0 through 1.10.x with the Absinthe relay node(id:...) query exposed. The critical constraint is that the attacker-supplied type segment, after base64 decoding and splitting, must resolve to an existing Elixir atom in the BEAM VM - String.to_existing_atom will raise for strings that have never been interned, which partially gates exploitation. However, this constraint is easily overcome: any atom that appears in the application's schema definitions, resource module names, enum values, or other startup-time code is a valid candidate, and the description explicitly notes that common resource names are easy to guess. No authentication, session state, or specific application configuration beyond relay support being enabled is required. Exploitation is limited to the relay node query endpoint; other GraphQL queries are unaffected.

The assigned CVSS 4.0 vector (AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:N) scores 6.9, confirming unauthenticated network exploitability with low confidentiality impact from stacktrace disclosure. However, the VA:N metric is inconsistent with both the 'Denial of Service' tag in the input and the description's explicit statement that the resolver crashes - the relay node query endpoint is at minimum rendered error-prone, suggesting VA:L is more accurate for the availability dimension; this discrepancy should be verified with the CNA. No EPSS score or CISA KEV listing is available, and no confirmed active exploitation exists. Attack complexity is genuinely low: crafting a relay ID with a plausible resource name type segment is trivial, and the description notes that common resource names are easy to guess. The one real constraint - the type atom must already exist in the BEAM VM - limits fully arbitrary strings but is easily satisfied by common Elixir module fragments or resource names interned during application startup. Real-world risk is bounded primarily by AshGraphql's niche deployment footprint in the Elixir/Ash ecosystem.

An unauthenticated attacker probes a Phoenix/AshGraphql application's GraphQL endpoint for relay support by issuing a node(id:...) introspection or test query. They craft a base64-encoded relay ID whose type segment is a common Elixir resource name or module fragment known to exist as a BEAM atom (e.g., a value guessed from the schema or a common naming convention), but is not a registered relay node type. Sending this ID as a node(id:...) query triggers Map.fetch!/2 to raise a KeyError that escapes Absinthe's error handling, resulting in a 500-class response that may include an internal stacktrace revealing module paths and application internals.