Vulnerability advisory

EEF-CVE-2026-82760

Superlinear base62 decoding exhausts CPU and memory in AshAuthentication API key sign-in

Published Sep 17, 2026Updated Sep 17, 2026OSV record ↗

Also known as CVE-2026-82760GHSA-q876-xr24-2mcx

Severity

CVSS 4.0CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

Affected versions

ash_authentication Hex

All ash_authentication advisories →

Affected	Fixed in
`4.8.0` to before 4.15.0	`4.15.0`Advisories →
`5.0.0-rc.0` to before 5.0.0-rc.14	`5.0.0-rc.14`Advisories →
Also listed as affected (45) `4.10.0` `4.11.0` `4.12.0` `4.13.0` `4.13.1` `4.13.2` `4.13.3` `4.13.4` `4.13.5` `4.13.6` `4.13.7` `4.14.0` `4.14.1` `4.14.2` `4.8.0` `4.8.1` `4.8.2` `4.8.3` `4.8.5` `4.8.6` `4.8.7` `4.9.0` `4.9.1` `4.9.2` `4.9.3` `4.9.4` `4.9.5` `4.9.6` `4.9.7` `4.9.8` `4.9.9` `5.0.0-rc.0` `5.0.0-rc.1` `5.0.0-rc.10` `5.0.0-rc.11` `5.0.0-rc.12` `5.0.0-rc.13` `5.0.0-rc.2` `5.0.0-rc.3` `5.0.0-rc.4` `5.0.0-rc.5` `5.0.0-rc.6` `5.0.0-rc.7` `5.0.0-rc.8` `5.0.0-rc.9`

Repository

Affected commits	Fixed by commit
GIT github.com/team-alembic/ash_authentication ↗
f3a53f480088419788d5c3934af3131fa9066773 to before d5a5d4cb5cc17fbd6e2a120a6111b47accad4b8e	`d5a5d4cb5cc17fbd6e2a120a6111b47accad4b8e`
Not specified	`dfb19c897853686ab481c5e773f7a1a0c74dea04`
Also listed as affected (45) `v4.14.2` `v5.0.0-rc.13` `v4.14.1` `v5.0.0-rc.12` `v5.0.0-rc.11` `v5.0.0-rc.10` `v4.14.0` `v4.13.7` `5.0.0-rc.9` `5.0.0-rc.8` `v5.0.0-rc.7` `v5.0.0-rc.6` `v5.0.0-rc.5` `v5.0.0-rc.4` `v5.0.0-rc.3` `v5.0.0-rc.2` `v5.0.0-rc.1` `v5.0.0-rc.0` `v4.13.6` `v4.13.5` `v4.13.4` `v4.13.3` `v4.13.2` `v4.13.1` `v4.13.0` `v4.12.0` `v4.11.0` `v4.10.0` `v4.9.9` `v4.9.8` `v4.9.7` `v4.9.6` `v4.9.5` `v4.9.4` `v4.9.3` `v4.9.2` `v4.9.1` `v4.9.0` `v4.8.7` `v4.8.5` `v4.8.4` `v4.8.3` `v4.8.2` `v4.8.1` `v4.8.0`

Description

Summary

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.