CVE-2026-55734: ueberauth guardian · Unthrottled Resource Allocation
Affects ueberauth guardianSource CVE Database V5
Not known to be exploited · CVSS 6.9 Medium : upgrade to 2.4.1 when convenient.
Data as of 31 Oct 2026, 08:20 UTC
- EPSS
- 0.4% chance of exploitation in 30 days – higher than 41% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 2.4.1, 8d4efbfc352d30f5fcfc75a4d69a795b0e472724
CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:HExploitation evidence
Disclosed: evidence found.
CVE published 1 Aug 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 30 Oct 2026.
What to do
Upgrade guardian to 2.4.1; guardian to 8d4efbfc352d30f5fcfc75a4d69a795b0e472724.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| ueberauthguardian | Affected
| Fixed in
|
| ueberauthguardian | Affected
| Fixed in
|
Hexguardianpkg:hex/guardianOther threats | Affected
| Fixed in
|
CPE configurations (1)
cpe:2.3:a:ueberauth:guardian:*:*:*:*:*:*:*:*
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
AI-suggested
If you cannot patch yet, avoid passing untrusted or attacker-controlled data to the encode_permissions!/1 function or related permission encoding routines. Consider implementing input validation or throttling on permission map keys to prevent uncontrolled atom creation.
Description
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
- github.com/ueberauth/guardian/security/advisories/GHSA-9qx2-v587-q3gg (opens in a new tab)
- cna.erlef.org/cves/CVE-2026-55734.html (opens in a new tab)
- osv.dev/vulnerability/EEF-CVE-2026-55734 (opens in a new tab)
- github.com/ueberauth/guardian/commit/8d4efbfc352d30f5fcfc75a4d69a795b0e472724 (opens in a new tab)