Allocation of Resources Without Limits or Throttling vulnerability in ueberauth guardian (Guardian.Permissions module) allows a denial of service via BEAM atom-table exhaustion.
This vulnerability is associated with program file lib/guardian/permissions.ex and program routines 'Elixir.Guardian.Permissions':encode_permissions!/1, 'Elixir.Guardian.Permissions':encode_permissions_into_claims!/2, 'Elixir.Guardian.Permissions':do_encode_permissions!/2.
The Guardian.Permissions mixin installs a public encode_permissions!/1 function on every module that does use Guardian.Permissions. For each key of the supplied map, encode_permissions!/1 calls String.to_atom(to_string(k)) before any validation runs. The integer-value clause of do_encode_permissions!/2 then short-circuits straight to encoding without validating the key against the configured permission set, so a key with an integer value is interned as a fresh atom with no exception raised. Atoms are never garbage collected and the BEAM atom table is a fixed-size resource (default roughly 1,048,576 entries), so each unique attacker-chosen key permanently consumes one slot. An attacker who can influence a permission map that reaches encode_permissions!/1 (for example a permissions map read from a request body and passed into token issuance via encode_permissions_into_claims!/2) can mint an unbounded number of atoms and exhaust the atom table, crashing the entire BEAM node and every service running on it. The sibling decode_permissions/1 is not affected because it skips keys absent from the configured permission set.
This issue affects guardian: from 2.0.0 before 2.4.1.
References
| Link | Resource |
|---|---|
| https://cna.erlef.org/cves/CVE-2026-55734.html | Third Party Advisory |
| https://github.com/ueberauth/guardian/commit/8d4efbfc352d30f5fcfc75a4d69a795b0e472724 | Patch |
| https://github.com/ueberauth/guardian/security/advisories/GHSA-9qx2-v587-q3gg | Exploit Patch Vendor Advisory |
| https://osv.dev/vulnerability/EEF-CVE-2026-55734 | Third Party Advisory |
| https://github.com/ueberauth/guardian/security/advisories/GHSA-9qx2-v587-q3gg | Exploit Patch Vendor Advisory |
Configurations
History
No history.
Information
Published : 2026-08-01 19:16
Updated : 2026-08-06 14:25
NVD link : CVE-2026-55734
Mitre link : CVE-2026-55734
CVE.ORG link : CVE-2026-55734
JSON object : View
Products Affected
ueberauth
- guardian
CWE
CWE-770
Allocation of Resources Without Limits or Throttling