Vulnerability · Published Sep 17, 2026 · Assigned by EEF
CVE-2026-82759Reversible IP address pseudonymisation in AshAuthentication audit log hash mode
Low 1.8
In plain English
A low-severity security flaw in ash_authentication from team-alembic. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.1% (higher than 3% of all known vulnerabilities).
Official description
Use 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. 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. This 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.
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| team-alembic | ash_authentication | 4.12.0 – before 4.15.05.0.0-rc.0 – before 5.0.0-rc.14 |
| team-alembic | ash_authentication | 255cfc9c0e511b7e0de39f8b3d676ae994fae06c – before * |
Weakness: CWE-760 · Vector: 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
References
- https://github.com/team-alembic/ash_authentication/security/advisories/GHSA-cgqj-pcpq-xhfm related, vendor-advisory
- EEF CNA record for CVE-2026-82759 related
- OSV record EEF-CVE-2026-82759 related
- Introducing commit 255cfc9 in team-alembic/ash_authentication related
- Fix commit d8a9c4b in team-alembic/ash_authentication patch
- Fix commit c3a6d5f in team-alembic/ash_authentication patch