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.
Published: 2026-09-17
Score: 1.8 Low
EPSS: n/a
KEV: No
Impact: n/a
Action: n/a
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Remediation

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History

Thu, 17 Sep 2026 13:30:00 +0000

Type Values Removed Values Added
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.
Title Reversible IP address pseudonymisation in AshAuthentication audit log hash mode
First Time appeared Team-alembic
Team-alembic ash Authentication
Weaknesses CWE-760
CPEs cpe:2.3:a:team-alembic:ash_authentication:*:*:*:*:*:*:*:*
Vendors & Products Team-alembic
Team-alembic ash Authentication
References
Metrics cvssV4_0

{'score': 1.8, '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'}


Subscriptions

Team-alembic Ash Authentication
cve-icon MITRE

Status: PUBLISHED

Assigner: EEF

Published:

Updated: 2026-09-17T13:08:21.929Z

Reserved: 2026-08-31T01:00:10.817Z

Link: CVE-2026-82759

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-09-17T14:17:33.030

Modified: 2026-09-17T14:17:33.030

Link: CVE-2026-82759

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

No data.

Weaknesses