CVE-2026-82760 Superlinear base62 decoding exhausts CPU and memory in AshAuthentication API key sign-in
Unauthenticated attackers can exhaust CPU and memory by submitting oversized API keys, causing denial of service in applications using AshAuthentication.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-82760?
CVE-2026-82760 is a high-severity denial of service vulnerability in team-alembic ash_authentication, published on 17 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official 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.
Weakness: CWE-407
Which versions are affected by CVE-2026-82760?
1 open source package ship an affected version, including ash_authentication.
| Package | Affected | Fixed in |
|---|---|---|
ash_authentication Hex | From 4.8.0 | 4.15.0, 5.0.0-rc.14 |
How do I fix CVE-2026-82760?
Upgrade ash_authentication to a fixed version for your release line: 4.15.0 or 5.0.0-rc.14.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-82760 being exploited?
There is no known exploitation of CVE-2026-82760 in the wild and no public exploit code.
Sources
Also known as EEF-CVE-2026-82760, GHSA-q876-xr24-2mcx.