{"affected":[{"package":{"ecosystem":"Hex","name":"ash_authentication","purl":"pkg:hex/ash_authentication"},"ranges":[{"events":[{"introduced":"4.12.0"},{"fixed":"4.15.0"}],"type":"SEMVER"},{"events":[{"introduced":"5.0.0-rc.0"},{"fixed":"5.0.0-rc.14"}],"type":"SEMVER"}],"versions":["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","5.0.0-rc.0","5.0.0-rc.1","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","5.0.0-rc.10","5.0.0-rc.11","5.0.0-rc.12","5.0.0-rc.13"]},{"ranges":[{"events":[{"introduced":"255cfc9c0e511b7e0de39f8b3d676ae994fae06c"},{"fixed":"d8a9c4b6bde828fdc8346198d5e4f588b5937541"},{"fixed":"c3a6d5fe0d4fd383ea81b0402db0a96638479478"}],"repo":"https://github.com/team-alembic/ash_authentication","type":"GIT"}]}],"aliases":["GHSA-cgqj-pcpq-xhfm","CVE-2026-82759"],"credits":[{"name":"Jonatan Männchen / EEF","type":"ANALYST"},{"name":"James Harton","type":"REMEDIATION_DEVELOPER"},{"name":"Peter Ullrich","type":"REPORTER"}],"database_specific":{"capec_ids":["CAPEC-112"],"cpe_ids":["cpe:2.3:a:team-alembic:ash_authentication:*:*:*:*:*:*:*:*"],"cwe_ids":["CWE-760"]},"details":"## Summary\n\nUse of a One-Way Hash with a Predictable Salt vulnerability in team-alembic AshAuthentication allows readers of the audit store to recover the client IP addresses that the audit log add-on's `:hash` privacy mode is meant to pseudonymise.\n\n`AshAuthentication.AddOn.AuditLog.IpPrivacy.hash_ip/1` computes a single unkeyed `:crypto.hash(:sha256, salt <> ip)` and truncates the result to 16 hexadecimal characters. The salt is read from the `:audit_log_ip_salt` or `:secret` application config keys, and falls back to the constant `\"default-salt-change-in-production\"` published in the library source when neither is set, with nothing warning that the default is in use. The IPv4 space is only 2^32 values and SHA-256 is fast, so the whole hash table is precomputable and every stored value maps back to its source address. Truncating to 16 characters does not help, and even a configured salt leaves the hash cheap enough to enumerate once it leaks.\n\nThis issue affects ash_authentication: from 4.12.0 before 4.15.0 and from 5.0.0-rc.0 before 5.0.0-rc.14.\n\n## Configurations\n\nOnly applications that enable the `audit_log` add-on and set its `ip_privacy` mode to `:hash` store the affected value. Other modes (`:none`, `:truncate`, `:exclude`) do not reach `hash_ip/1`.\n\nThe complete break additionally requires the default salt, that is neither `:audit_log_ip_salt` nor `:secret` configured under the `:ash_authentication` application. This is the out-of-the-box state: no warning or error is raised when the hardcoded salt is in use.","id":"EEF-CVE-2026-82759","modified":"2026-09-17T13:08:22.393759Z","published":"2026-09-17T13:08:21.929Z","references":[{"type":"ADVISORY","url":"https://github.com/team-alembic/ash_authentication/security/advisories/GHSA-cgqj-pcpq-xhfm"},{"type":"WEB","url":"https://cna.erlef.org/cves/CVE-2026-82759.html"},{"type":"WEB","url":"https://github.com/team-alembic/ash_authentication/commit/255cfc9c0e511b7e0de39f8b3d676ae994fae06c"},{"type":"FIX","url":"https://github.com/team-alembic/ash_authentication/commit/d8a9c4b6bde828fdc8346198d5e4f588b5937541"},{"type":"FIX","url":"https://github.com/team-alembic/ash_authentication/commit/c3a6d5fe0d4fd383ea81b0402db0a96638479478"},{"type":"PACKAGE","url":"https://hex.pm/packages/ash_authentication"}],"related":[],"schema_version":"1.7.3","severity":[{"score":"CVSS:4.0/AV:L/AC:L/AT:P/PR:H/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N","type":"CVSS_V4"}],"summary":"Reversible IP address pseudonymisation in AshAuthentication audit log hash mode","upstream":[]}