Atom table exhaustion via attacker-controlled GraphQL SDL names in absinthe

Allocation of Resources Without Limits or Throttling vulnerability in absinthe-graphql absinthe allows unauthenticated denial of service via atom table exhaustion when parsing attacker-controlled GraphQL SDL.

Multiple Blueprint.Draft.convert/2 implementations in Absinthe's SDL language modules call String.to_atom/1 on attacker-controlled names from parsed GraphQL SDL documents, including directive names, field names, type names, and argument names. Because atoms are never garbage-collected and the BEAM atom table has a fixed limit (default 1,048,576), each unique name permanently consumes one slot. An attacker can exhaust the atom table by submitting SDL documents containing enough unique names, causing the Erlang VM to abort with system_limit and taking down the entire node.

Any application that passes attacker-controlled GraphQL SDL through Absinthe's parser is exposed — for example, a schema-upload endpoint, a federation gateway that ingests remote SDL, or any developer tool that runs the parser over user-supplied documents.

This issue affects absinthe: from 1.5.0 before 1.10.2.