MediumCVE-2026-74994

    inets, httpd: Authentication Bypass via Directory Namespace Collapse in httpd mod_auth (CVE-2026-74994)

    Published Last modified Sources: Red Hat, Debian, BSI, OSV, CVE.org, Msrc Update Guide

    What is affected, what to do

    The mod_auth module in OTP's inets httpd server, when configured with dets or mnesia authentication backends and multiple directory configuration blocks, collapses all directory blocks into a single shared user/group namespace. A user added to one protected directory is accepted as valid for all other protected directories on the same server instance.

    Update Erlang OTP to version 27.3.4.17, Erlang OTP to version 28.5.0.6, Erlang OTP to version 29.0.6.

    Affected
    • Erlang OTP lt 17.0..27.3.4.17
    • Erlang OTP lt 28.0..28.5.0.6
    • Erlang OTP lt 29.0..29.0.6
    • Erlang OTP lt 5.10..9.3.2.7
    • Erlang OTP lt 9.4..9.6.2.3
    • Erlang OTP lt 9.7..9.7.2
    Fixed in
    • Erlang OTP 27.3.4.17
    • Erlang OTP 28.5.0.6
    • Erlang OTP 29.0.6
    • Erlang OTP 9.3.2.7
    • Erlang OTP 9.6.2.3
    • Erlang OTP 9.7.2

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

    Metrics

    6.0

    Priority

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

    Source: Vendor (CNA), CVSS v4

    6.0

    CVSS v4

    Severity Medium on the scale from 0 to 10.

    Source: Red Hat, Debian, BSI, OSV, CVE.org, Msrc Update Guide

    0.6 %

    EPSS score

    Low — model estimates < 1% exploitation likelihood.

    Source: FIRST EPSS, percentile 50.2

    Show all metrics
    Severity
    Medium
    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
    75.39 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
    6.0 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
    6.0
    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“.

    Read in glossary
    0.6 %
    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
    50.2
    High — this CVE ranks above the median of all CVEs scored today (rank ≥ 36%).
    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 1 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-863, CWE-1289

    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

    The mod_auth module in OTP's inets httpd server, when configured with dets or mnesia authentication backends and multiple directory configuration blocks, collapses all directory blocks into a single shared user/group namespace. A user added to one protected directory is accepted as valid for all other protected directories on the same server instance. This issue affects OTP from OTP 17.0 before OTP 27.3.4.17, from OTP 28.0 before OTP 28.5.0.6, and from OTP 29.0 before OTP 29.0.6, corresponding to inets from 5.10 before 9.3.2.7, from 9.4 before 9.6.2.3, and from 9.7 before 9.7.2. Whether OTP before OTP 17.0, corresponding to inets before 5.10, is affected is unknown.

    Source: redhat_csaf, Debian Security Advisories, BSI WID Portal, BSI CSAF, OSV (Open Source Vulnerabilities), cvelistv5, NVD (NIST), Microsoft Security Update Guide

    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
    ErlangOTP
    • 28.0 – < 28.5.0.6
    • 5.10 – < 9.3.2.7
    • 9.4 – < 9.6.2.3
    • 29.0 – < 29.0.6
    • 17.0 – < 27.3.4.17
    • 9.7 – < 9.7.2
    • 28.5.0.6
    • 9.3.2.7
    • 9.6.2.3
    • 29.0.6
    • 27.3.4.17
    • 9.7.2
    Open SourceErlang/OTP
    • < 28.5.0.6
    • < 27.3.4.17
    • < 29.0.6
    • 28.5.0.6
    • 27.3.4.17
    • 29.0.6

    Vendors and products

    Affected operating systems

    Affected operating systems
    Linuxdebianerlangtrixie

    Weakness classes (CWE)

    • CWE-863Incorrect Authorization

      Class

      The product performs an authorization check when an actor attempts to access a resource or perform an action, but it does not correctly perform the check.

      Entry at MITRE CWE-863

    • CWE-1289Improper Validation of Unsafe Equivalence in Input

      Base

      The product receives an input value that is used as a resource identifier or other type of reference, but it does not validate or incorrectly validates that the input is equivalent to a potentially-unsafe value.

      Entry at MITRE CWE-1289

    References & sources

    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 modifiedEEF

      1 individual change: Affected versions (publisher)

      Show the original change
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Affected versions (publisher)added
      —
      Affected value modified. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/74xxx/CVE-2026-74994.json">CVE-2026-74994</a>

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

    2. 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-2026-74994","role":"CISA Coordinator","options":[{"exploitation":"none"},{"automatable":"no"},{"technicalImpact":"partial"}],"version":"2.0.3","timestamp":"2026-09-01T15:57:45.946562Z"}

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

    3. ReceivedEEF

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

      Weakness type: CWE-863, CWE-1289

      Description added or changed

      Show 11 original changes
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Descriptionadded
      —
      The mod_auth module in OTP's inets httpd server, when configured with dets or mnesia authentication backends and multiple directory configuration blocks, collapses all directory blocks into a single shared user/group namespace. A user added to one protected directory is accepted as valid for all other protected directories on the same server instance. This issue affects OTP from OTP 17.0 before OTP 27.3.4.17, from OTP 28.0 before OTP 28.5.0.6, and from OTP 29.0 before OTP 29.0.6, corresponding to inets from 5.10 before 9.3.2.7, from 9.4 before 9.6.2.3, and from 9.7 before 9.7.2. Whether OTP before OTP 17.0, corresponding to inets before 5.10, is affected is unknown.
      CVSSadded
      —
      AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/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-863
      Weakness type (CWE)added
      —
      CWE-1289
      Affected versions (publisher)added
      —
      New affected value received. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/74xxx/CVE-2026-74994.json">CVE-2026-74994</a>
      Referenceadded
      —
      https://cna.erlef.org/cves/CVE-2026-74994.html
      Referenceadded
      —
      https://github.com/erlang/otp/commit/6101cb74ff2870718c622ba7af0c100f7f2524e3
      Referenceadded
      —
      https://github.com/erlang/otp/commit/6982e381137ede21a4e1faf5fa2dd82321691176
      Referenceadded
      —
      https://github.com/erlang/otp/commit/c5ccec8ed25c70ec6557fd81277e4b2f52285c19
      Referenceadded
      —
      https://github.com/erlang/otp/security/advisories/GHSA-c3cq-q8x6-547g
      Referenceadded
      —
      https://osv.dev/vulnerability/EEF-CVE-2026-74994

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

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