CVE-2026-82759
Reversible IP address pseudonymisation in AshAuthentication audit log hash mode
- State
- Published
- Severity
- 1.8 Low
- Published
- Sep 17, 2026
- Updated
- Sep 17, 2026
- Reserved
- Aug 31, 2026
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.
Scores
| CVSS | Score | Vector | Source |
|---|---|---|---|
| 4.0 | 1.8 Low | 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 | EEF |
Weaknesses
- CWE-760 Use of a One-Way Hash with a Predictable Salt
Affected Products
| Product | Versions |
|---|---|
ash_authenticationteam-alembic |
|
ash_authenticationteam-alembic |
|
References
- https://github.com/team-alembic/ash_authentication/security/advisories/GHSA-cgqj-pcpq-xhfmrelatedvendor-advisory
- EEF CNA record for CVE-2026-82759related
- OSV record EEF-CVE-2026-82759related
- Introducing commit 255cfc9 in team-alembic/ash_authenticationrelated
- Fix commit d8a9c4b in team-alembic/ash_authenticationpatch
- Fix commit c3a6d5f in team-alembic/ash_authenticationpatch
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