LowCVE-2026-82759

    Reversible IP address pseudonymisation in AshAuthentication audit log hash mode (CVE-2026-82759)

    Published Last modified Sources: CVE.org, OSV

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    What is affected, what to do

    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.

    Update Team-alembic Ash Authentication to version 4.15.0, Team-alembic Ash Authentication to version 5.0.0-rc.14.

    Affected
    • Team-alembic Ash Authentication lt 4.12.0..4.15.0
    • Team-alembic Ash Authentication lt 5.0.0-rc.0..5.0.0-rc.14
    Fixed in
    • Team-alembic Ash Authentication 4.15.0
    • Team-alembic Ash Authentication 5.0.0-rc.14

    Not sure whether and how you are affected? Ask a question about this vulnerability

    Metrics

    1.8

    Priority

    XIEM Effective CVSS: highest available CVSS rating from NVD and vendor data.

    Source: Vendor (CNA), CVSS v4

    1.8

    CVSS v4

    Severity Low on the scale from 0 to 10.

    Source: CVE.org, OSV

    0.1 %

    EPSS score

    Low — model estimates < 1% exploitation likelihood.

    Source: FIRST EPSS, percentile 3.3

    Show all metrics
    Severity
    Low
    Priority (0–325)

    The priority score is a consolidated metric that condenses several individual signals into a single, action-guiding ranking: technical severity (CVSS), exploitation likelihood (EPSS), known-exploited status (KEV) and the context of the affected asset. The aim is to answer the only truly important question in vulnerability management: what first?

    Read in glossary
    35.38 Methodology
    Exploit maturity

    An exploit is code or a technique that specifically uses a concrete vulnerability to force unintended behaviour — such as executing code or escalating privileges. It is the tool that turns a theoretical flaw into a practical attack.

    Read in glossary
    no public PoC known
    XIEM Effective CVSS

    XIEM® is the tiered managed-security operating model from NEOSEC and a registered trademark of NEOSEC GmbH. It extends classic SIEM — the central collection, normalisation and correlation of security-relevant events — with endpoint forensics, network visibility and deception technology, and consolidates them into three building tiers: Sentry, Orchestrate and Command.

    Read in glossary
    1.8 Methodology
    CVSS v4

    CVSS is the globally established, open standard for assessing the technical severity of a vulnerability on a scale from 0 to 10. It describes how easily a flaw can be exploited and what damage it can cause — but not how likely its actual exploitation is. CVSS and the complementary EPSS deliberately answer different questions.

    Read in glossary
    1.8
    EPSS score

    The EPSS score is the absolute model output for an individual vulnerability: the estimated probability of real-world exploitation within the next 30 days, expressed as a value between 0 and 1 (i.e. 0 % to 100 %). A score of 0.42 means „the model estimates a 42 % chance of real-world exploitation within 30 days“.

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    0.1 %
    Low — model estimates < 1% exploitation likelihood.
    EPSS percentile

    The EPSS percentile is the relative position of a vulnerability within all EPSS-scored CVEs, expressed as a value between 0 and 1. A percentile of 0.90 means „this CVE has a higher EPSS score than 90 % of all other scored CVEs“. Unlike the EPSS score, it is not a probability — but a positioning within a ranking.

    Read in glossary
    3.3
    Low — this CVE sits in the lower 10% of all CVEs scored today.
    KEV status

    The KEV catalogue is a list maintained by the US authority CISA of vulnerabilities for which active exploitation in the wild has been confirmed. It answers not the question „how severe?“ but „is it already being attacked?“ — thereby sharply prioritising patching.

    Read in glossary
    —
    Published
    CISA assessment (SSVC)
    Exploitation: none known · not automatable · Technical impact: partial
    Source: CISA Vulnrichment, as of 17 September 2026
    CWE

    CWE is a catalogue of typical weakness types in software and hardware — such as flawed input validation, unsafe memory handling or poor authentication. Where a CVE names a concrete vulnerability in a concrete product, a CWE describes the underlying class of defect.

    Read in glossary
    CWE-760

    Detection rules

    No NEOSEC detection rule is available for this vulnerability yet.

    Classification under NIS2 and CRA

    Rule-based classification from exploitation status and severity. It does not replace a case-by-case assessment.

    NIS2

    NIS2 is EU Directive (EU) 2022/2555 to raise the level of cybersecurity across the Union. It substantially broadens obligations compared with the first NIS directive: more sectors, mandatory risk management, staged reporting duties and personal accountability of senior management.

    Read in glossary
    Handle the vulnerability in regular vulnerability handling under Art. 21(2)(e) NIS2.
    CRA

    The CRA is EU Regulation (EU) 2024/2847 setting horizontal cybersecurity requirements for „products with digital elements“ — from industrial controllers and software to connected consumer devices. For the first time manufacturers must ensure security across the entire product lifecycle, handle vulnerabilities and provide security updates.

    Read in glossary
    From 11.12.2027, Annex I Part II CRA requires manufacturers of affected products with digital elements to handle vulnerabilities without delay and provide security updates.
    ISO/IEC 27001

    ISO/IEC 27001 is the internationally leading standard for an information security management system (ISMS). It describes a risk-based, process-oriented framework to systematically plan, implement, review and improve information security.

    Read in glossary
    Control A.8.8, management of technical vulnerabilities: assess relevance to your systems, plan remediation and keep evidence.

    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.

    Source: NVD (NIST), cvelistv5, OSV (Open Source Vulnerabilities)

    Affected products

    The following versions are affected. Older releases of the same product line are also vulnerable unless stated otherwise.

    Affected products
    Affected versionsFixed in
    team-alembicash_authentication
    • 4.12.0 – < 4.15.0
    • 5.0.0-rc.0 – < 5.0.0-rc.14
    • 4.15.0
    • 5.0.0-rc.14
    hexash_authentication
    • 4.13.2
    • 4.14.2
    • 4.13.5
    • 5.0.0-rc.5
    • 5.0.0-rc.7
    • 5.0.0-rc.6
    • 4.14.1
    • 5.0.0-rc.3
    • 5.0.0-rc.4
    • 4.13.7
    • 5.0.0-rc.12
    • 4.13.0
    • 4.13.6
    • 5.0.0-rc.8
    • 4.12.0
    • 4.13.1
    • 5.0.0-rc.13
    • 5.0.0-rc.0
    • 5.0.0-rc.9
    • 4.13.4
    • 5.0.0-rc.10
    • 4.14.0
    • 4.13.3
    • 5.0.0-rc.2
    • 5.0.0-rc.11
    • 5.0.0-rc.1
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    Vendors and products

    Weakness classes (CWE)

    • CWE-760Use of a One-Way Hash with a Predictable Salt

      Variant

      The product uses a one-way cryptographic hash against an input that should not be reversible, such as a password, but the product uses a predictable salt as part of the input.

      Entry at MITRE CWE-760

    References & sources

    • github.comteam-alembic/ash_authentication/security/advisories/GHSA-cgqj-p…related, Vendor advisory
    • cna.erlef.orgEEF CNA record for CVE-2026-82759related
    • OSV (Open Source Vulnerabilities)OSV record EEF-CVE-2026-82759related
    • github.comIntroducing commit 255cfc9 in team-alembic/ash_authenticationrelated
    • github.comFix commit d8a9c4b in team-alembic/ash_authenticationPatch
    • github.comFix commit c3a6d5f in team-alembic/ash_authenticationPatch
    • hex.pmpackages/ash_authenticationpackage

    Changes to this CVE

    Who changed this CVE and when: NVD (analysis, affected products, CVSS), the CVE publisher (CNA) and additional providers such as CISA (ADP).

    1. Record modifiedCISA ADP

      CISA assessment (SSVC): exploitation: none known, automatable: no

      Show the original change
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      SSVC assessmentadded
      —
      {"id":"CVE-2026-82759","role":"CISA Coordinator","options":[{"exploitation":"none"},{"automatable":"no"},{"technicalImpact":"partial"}],"version":"2.0.3","timestamp":"2026-09-17T18:19:03.885925Z"}

      Source identifier: 134c704f-9b21-4f2e-91b3-4a467353bcc0

    2. ReceivedEEF

      CVSS V4.0: AV:L/AC:L/AT:P/PR:H/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N

      Weakness type: CWE-760

      Description added or changed

      Show 10 original changes
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Descriptionadded
      —
      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.
      CVSSadded
      —
      AV:L/AC:L/AT:P/PR:H/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
      Weakness type (CWE)added
      —
      CWE-760
      Affected versions (publisher)added
      —
      New affected value received. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/82xxx/CVE-2026-82759.json">CVE-2026-82759</a>
      Referenceadded
      —
      https://cna.erlef.org/cves/CVE-2026-82759.html
      Referenceadded
      —
      https://github.com/team-alembic/ash_authentication/commit/255cfc9c0e511b7e0de39f8b3d676ae994fae06c
      Referenceadded
      —
      https://github.com/team-alembic/ash_authentication/commit/c3a6d5fe0d4fd383ea81b0402db0a96638479478
      Referenceadded
      —
      https://github.com/team-alembic/ash_authentication/commit/d8a9c4b6bde828fdc8346198d5e4f588b5937541
      Referenceadded
      —
      https://github.com/team-alembic/ash_authentication/security/advisories/GHSA-cgqj-pcpq-xhfm
      Referenceadded
      —
      https://osv.dev/vulnerability/EEF-CVE-2026-82759

      Source identifier: 6b3ad84c-e1a6-4bf7-a703-f496b71e49db

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