CVE-2026-82759

Reversible IP address pseudonymisation in AshAuthentication audit log hash mode

CVSS 4.0 1.8 LOWCheck source for fixed versionsKEV status unknown

Original advisory

cve-program · CVE-2026-82759

Published

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.

Read the publisher's advisory

Affected versions, risk and source history

cve-program · CVE-2026-82759

Published

ash_authentication

https://repo.hex.pm

Publisher's version information

Shown as published. These rules are not interpreted as NuGet package version ranges.

{
                    "collectionURL": "https://repo.hex.pm",
                    "cpes": [
                        "cpe:2.3:a:team-alembic:ash_authentication:*:*:*:*:*:*:*:*"
                    ],
                    "defaultStatus": "unaffected",
                    "modules": [
                        "'Elixir.AshAuthentication.AddOn.AuditLog.IpPrivacy'"
                    ],
                    "packageName": "ash_authentication",
                    "packageURL": "pkg:hex/ash_authentication",
                    "product": "ash_authentication",
                    "programFiles": [
                        "lib/ash_authentication/add_ons/audit_log/ip_privacy.ex"
                    ],
                    "programRoutines": [
                        {
                            "name": "'Elixir.AshAuthentication.AddOn.AuditLog.IpPrivacy':hash_ip/1"
                        },
                        {
                            "name": "'Elixir.AshAuthentication.AddOn.AuditLog.IpPrivacy':apply_privacy/3"
                        }
                    ],
                    "repo": "https://github.com/team-alembic/ash_authentication",
                    "vendor": "team-alembic",
                    "versions": [
                        {
                            "lessThan": "4.15.0",
                            "status": "affected",
                            "version": "4.12.0",
                            "versionType": "semver"
                        },
                        {
                            "lessThan": "5.0.0-rc.14",
                            "status": "affected",
                            "version": "5.0.0-rc.0",
                            "versionType": "semver"
                        }
                    ]
                }

team-alembic/ash_authentication

https://github.com

Publisher's version information

Shown as published. These rules are not interpreted as NuGet package version ranges.

{
                    "collectionURL": "https://github.com",
                    "cpes": [
                        "cpe:2.3:a:team-alembic:ash_authentication:*:*:*:*:*:*:*:*"
                    ],
                    "defaultStatus": "unaffected",
                    "modules": [
                        "'Elixir.AshAuthentication.AddOn.AuditLog.IpPrivacy'"
                    ],
                    "packageName": "team-alembic/ash_authentication",
                    "packageURL": "pkg:github/team-alembic/ash_authentication",
                    "product": "ash_authentication",
                    "programFiles": [
                        "lib/ash_authentication/add_ons/audit_log/ip_privacy.ex"
                    ],
                    "programRoutines": [
                        {
                            "name": "'Elixir.AshAuthentication.AddOn.AuditLog.IpPrivacy':hash_ip/1"
                        },
                        {
                            "name": "'Elixir.AshAuthentication.AddOn.AuditLog.IpPrivacy':apply_privacy/3"
                        }
                    ],
                    "repo": "https://github.com/team-alembic/ash_authentication",
                    "vendor": "team-alembic",
                    "versions": [
                        {
                            "changes": [
                                {
                                    "at": "d8a9c4b6bde828fdc8346198d5e4f588b5937541",
                                    "status": "unaffected"
                                },
                                {
                                    "at": "c3a6d5fe0d4fd383ea81b0402db0a96638479478",
                                    "status": "unaffected"
                                }
                            ],
                            "lessThan": "*",
                            "status": "affected",
                            "version": "255cfc9c0e511b7e0de39f8b3d676ae994fae06c",
                            "versionType": "git"
                        }
                    ]
                }

Original source record · Cite this exact observation · Complete original publisher JSON