Guardian.Plug.Keys derives connection and session namespace keys by passing arbitrary binaries to String.to_atom/1. base_key/1 in lib/guardian/plug/keys.ex converts any binary into the atom :"guardian_<input>", and the derived helpers claims_key/1, resource_key/1, and token_key/1 create a second atom on top of that. key_from_other/1 likewise converts a regex-captured binary through String.to_atom/1. The public specs advertise String.t() as a valid argument, so passing a string is documented usage, and higher-level entry points such as Guardian.Plug.current_token(conn, key: key) thread the caller-supplied key straight into these functions.
String.to_atom/1 creates a brand-new atom for every previously unseen binary, atoms are never garbage collected, and the BEAM atom table is fixed at roughly 1,048,576 entries by default. An application that routes attacker-influenced data (a tenant identifier, header, or other request input) into a Guardian key therefore mints one permanent atom per distinct value. A modest stream of varied, unauthenticated input permanently consumes the atom table and crashes the BEAM node, taking down every application running on it.
This issue affects guardian: from 0.1.0 before 2.4.1.
Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).
| Vendor | Product | Default status | Versions | ||||||
|---|---|---|---|---|---|---|---|---|---|
| ueberauth | guardian | unaffected |
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| ueberauth | guardian | unaffected |
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No advisories yet.
Solution
No solution given by the vendor.
Workaround
Do not derive Guardian keys from untrusted input. Use a fixed, hardcoded set of namespace keys, or validate the value against a bounded allowlist of known keys, before passing it as the :key option.
Sat, 01 Aug 2026 19:00:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Description | Allocation of Resources Without Limits or Throttling in ueberauth guardian allows denial of service via unbounded atom creation from attacker-influenced binary input. Guardian.Plug.Keys derives connection and session namespace keys by passing arbitrary binaries to String.to_atom/1. base_key/1 in lib/guardian/plug/keys.ex converts any binary into the atom :"guardian_<input>", and the derived helpers claims_key/1, resource_key/1, and token_key/1 create a second atom on top of that. key_from_other/1 likewise converts a regex-captured binary through String.to_atom/1. The public specs advertise String.t() as a valid argument, so passing a string is documented usage, and higher-level entry points such as Guardian.Plug.current_token(conn, key: key) thread the caller-supplied key straight into these functions. String.to_atom/1 creates a brand-new atom for every previously unseen binary, atoms are never garbage collected, and the BEAM atom table is fixed at roughly 1,048,576 entries by default. An application that routes attacker-influenced data (a tenant identifier, header, or other request input) into a Guardian key therefore mints one permanent atom per distinct value. A modest stream of varied, unauthenticated input permanently consumes the atom table and crashes the BEAM node, taking down every application running on it. This issue affects guardian: from 0.1.0 before 2.4.1. | |
| Title | Atom-table exhaustion denial of service in Guardian via unbounded atom creation from binary keys | |
| First Time appeared |
Ueberauth
Ueberauth guardian |
|
| Weaknesses | CWE-770 | |
| CPEs | cpe:2.3:a:ueberauth:guardian:*:*:*:*:*:*:*:* | |
| Vendors & Products |
Ueberauth
Ueberauth guardian |
|
| References |
| |
| Metrics |
cvssV4_0
|
Projects
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MITRE
Status: PUBLISHED
Assigner: EEF
Published:
Updated: 2026-08-01T18:46:05.861Z
Reserved: 2026-06-16T10:47:13.915Z
Link: CVE-2026-54894
Vulnrichment
No data.
NVD
No data.
Redhat
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OpenCVE Enrichment
No data.