dbcve.org
Erlang\/inetsApplication · Erlang

CVE-2026-28808

CRITICAL · 9.8 CVSS v3.1 Published 2026-04-07
Fix available
A fix is available. Upgrade to 9.1.0.6 / 9.3.2.4 or later.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable No privileges Zero-click Patch available

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
Incorrect Authorization vulnerability in Erlang OTP (inets modules) allows unauthenticated access to CGI scripts protected by directory rules when served via script_alias. When script_alias maps a URL prefix to a directory outside DocumentRoot, mod_auth evaluates directory-based access controls against the DocumentRoot-relative path while mod_cgi executes the script at the ScriptAlias-resolved path. This path mismatch allows unauthenticated access to CGI scripts that directory rules were meant to protect. This vulnerability is associated with program files lib/inets/src/http_server/mod_alias.erl, lib/inets/src/http_server/mod_auth.erl, and lib/inets/src/http_server/mod_cgi.erl. This issue affects OTP from OTP 17.0 before OTP 28.4.2, OTP 27.3.4.10 and OTP 26.2.5.19, corresponding to inets from 5.10 before 9.6.2, 9.3.2.4 and 9.1.0.6.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

In Erlang OTP's inets HTTP server, an incorrect authorization vulnerability exists where mod_auth evaluates directory-based access controls against the DocumentRoot-relative path while mod_cgi executes the script at the ScriptAlias-resolved path. This path mismatch allows unauthenticated attackers to bypass directory protection rules and execute CGI scripts that should be restricted, achieving unauthenticated remote code execution.

MitigationUpgrade Erlang OTP/inets to versions 28.4.2, 27.3.4.10, 26.2.5.19, or the corresponding inets versions 9.6.2, 9.3.2.4, 9.1.0.6. Alternatively, ensure CGI scripts are not placed in directories accessible via script_alias configurations that map outside DocumentRoot.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Erlang\/inetsApplication
Affected:>= 5.10, < 9.1.0.6> 9.2, < 9.3.2.4> 9.4, < 9.6.2
Erlang\/otpApplication
Affected:>= 17.0, < 26.2.5.19>= 27.0, < 27.3.4.10>= 28.0, < 28.4.2

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify Erlang/OTP or inets version
    Run 'erl -eval "erlang:display(erlang:system_info(otp_release)), halt()." -noshell' or check your Erlang installation via 'erl' and call erlang:system_info(otp_release). For inets specifically, check the inets version with 'inets:version()' or via the inets app file.
    Affected if The installed Erlang/OTP version falls within: >= 17.0 and < 26.2.5.19; OR >= 27.0 and < 27.3.4.10; OR >= 28.0 and < 28.4.2. Alternatively, inets version is >= 5.10 and < 9.1.0.6; OR > 9.2 and < 9.3.2.4; OR > 9.4 and < 9.6.2.
  2. Verify inets HTTP server is running
    Check if the inets application is started: connect to the Erlang node and run 'application:which_applications()' to see if inets is listed, or check your system's running processes for an inets HTTP server instance.
    Affected if inets HTTP server is actively running and serving HTTP requests.
  3. Confirm mod_cgi is enabled
    Examine your inets configuration file (typically inets.conf or httpd.conf) and look for the mod_cgi module being loaded, or check for ScriptAlias directives that map URL prefixes to CGI script directories.
    Affected if mod_cgi is enabled and ScriptAlias directives are configured to map URL prefixes to CGI script directories.
  4. Check for mod_auth directory-based access controls
    Examine the inets configuration for mod_auth setup, specifically look for <Directory> blocks or auth configuration that restricts access to specific paths based on authentication rules.
    Affected if mod_auth is configured with directory-based access control rules (such as require valid-user or require user) protecting CGI script paths.
  5. Identify script_alias mapping outside DocumentRoot
    Review your inets configuration for ScriptAlias directives. Compare the directory path specified in each ScriptAlias directive against the DocumentRoot setting. ScriptAlias maps a URL prefix to a filesystem path.
    Affected if A ScriptAlias directive maps a URL prefix to a directory that is NOT under the DocumentRoot directory, AND that directory contains CGI scripts protected by mod_auth access controls.

You are affected if you run a vulnerable Erlang/OTP/inets version AND have inets HTTP server running with mod_cgi enabled AND use ScriptAlias to map CGI scripts outside DocumentRoot while those scripts are protected by mod_auth directory-based access controls.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 9.1.0.6 / 9.3.2.4 / 9.6.2 or later
Fixed in 9.1.0.69.3.2.49.6.2
Vendor patch github.com →
Interim mitigation

Upgrade Erlang OTP/inets to versions 28.4.2, 27.3.4.10, 26.2.5.19, or the corresponding inets versions 9.6.2, 9.3.2.4, 9.1.0.6. Alternatively, ensure CGI scripts are not placed in directories accessible via script_alias configurations that map outside DocumentRoot.

Recommended fix High confidence

Erlang/OTP 28.4.2 (or 27.3.4.10 for OTP 27.x, or 26.2.5.19 for OTP 26.x)

  1. 1. Identify the current Erlang/OTP and inets versions running in your environment using 'erl -eval "erlang:display(erlang:system_info(otp_release)), halt()." -noshell' or checking your package manager.
  2. 2. For Erlang/OTP 26.x users: upgrade to OTP 26.2.5.19 or later.
  3. 3. For Erlang/OTP 27.x users: upgrade to OTP 27.3.4.10 or later.
  4. 4. For Erlang/OTP 28.x users: upgrade to OTP 28.4.2 or later.
  5. 5. Alternatively, if using inets standalone: upgrade to inets 9.1.0.6, 9.3.2.4, or 9.6.2 depending on your base OTP version.
  6. 6. After upgrading, verify the inets version matches one of the fixed releases by checking the inets app version in the Erlang shell: 'application:version(inets).'
  7. 7. Test that CGI script access controls now correctly enforce directory-based authorization rules.
  8. 8. Review and test any CGI scripts that were previously protected by directory rules to confirm they now require proper authentication.
Caveat Minor: This is a security patch with no expected breaking changes; however, test CGI authentication flows to verify the fix does not alter expected behavior.

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Erlang\/inets Scoped from the published advisory
  • Consultation4.0 h
  • Implementation12.0 h
  • Testing8.0 h
  • Review / QA4.0 h
28.0 hours of engineering $4,880
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

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