CVE-2026-82760
Superlinear base62 decoding exhausts CPU and memory in AshAuthentication API key sign-in
- State
- Published
- Severity
- 8.2 High
- Published
- Sep 17, 2026
- Updated
- Sep 17, 2026
- Reserved
- Aug 31, 2026
Description
Inefficient Algorithmic Complexity vulnerability in team-alembic AshAuthentication allows an unauthenticated attacker to exhaust CPU and memory via an oversized base62 segment in a submitted API key.
AshAuthentication.Base.decode62/1 in lib/ash_authentication/base.ex splits its argument into one binary per character and folds it with charval62/2, which recomputes Integer.pow(62, index) at every position instead of accumulating by Horner's method, so cost grows roughly cubically in the input length. bindecode62/1 in the same module is quadratic through Integer.undigits/2 and Integer.digits/2. Neither function caps byte_size/1, and AshAuthentication.Strategy.ApiKey.SignInPreparation passes the underscore-separated segments of the submitted key straight into both, before any key lookup and without prior authentication. The surrounding rescue clauses catch exceptions, not CPU or memory exhaustion.
This issue affects ash_authentication: from 4.8.0 before 4.15.0 and from 5.0.0-rc.0 before 5.0.0-rc.14.
Scores
| CVSS | Score | Vector | Source |
|---|---|---|---|
| 4.0 | 8.2 High | CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N | EEF |
Weaknesses
- CWE-407 Inefficient Algorithmic Complexity
Affected Products
| Product | Versions |
|---|---|
ash_authenticationteam-alembic |
|
ash_authenticationteam-alembic |
|
References
- https://github.com/team-alembic/ash_authentication/security/advisories/GHSA-q876-xr24-2mcxrelatedvendor-advisory
- EEF CNA record for CVE-2026-82760related
- OSV record EEF-CVE-2026-82760related
- Introducing commit f3a53f4 in team-alembic/ash_authenticationrelated
- Fix commit d5a5d4c in team-alembic/ash_authenticationpatch
- Fix commit dfb19c8 in team-alembic/ash_authenticationpatch
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