# CVE-2026-28808: ScriptAlias CGI targets bypass directory auth in inets httpd (mod_auth vs mod_cgi path mismatch)

> Attackers can bypass directory authentication to access protected CGI scripts in Erlang OTP inets when ScriptAlias is used.

- **Severity:** High 8.3 (`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`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 7 Apr 2026
- **Updated:** 22 Sep 2026
- **Also known as:** AZL-83390, DEBIAN-CVE-2026-28808, EEF-CVE-2026-28808, GHSA-3vhp-h532-mc3f, OESA-2026-2572, OESA-2026-2573, UBUNTU-CVE-2026-28808

## What is CVE-2026-28808?

CVE-2026-28808 is a high-severity missing authorization vulnerability in Erlang OTP, published on 7 Apr 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official 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.

Weakness: CWE-551 (Incorrect Behavior Order: Authorization Before Parsing and Canonicalization), CWE-863 (Incorrect Authorization)

## Which versions are affected by CVE-2026-28808?

It affects 2 products.


Products: Erlang Erlang\/Inets, Erlang Erlang\/Otp.

## How do I fix CVE-2026-28808?

Upgrade to a fixed version.

## Is CVE-2026-28808 being exploited?

There is no known exploitation of CVE-2026-28808 in the wild and no public exploit code.

## Other vulnerabilities in Erlang OTP

- [CVE-2026-48856](https://insights.sbomify.com/CVE-2026-48856/): httpc leaks Authorization header to cross-origin redirect targets (high 7.1)
- [CVE-2026-23941](https://insights.sbomify.com/CVE-2026-23941/): Request smuggling via first-wins Content-Length parsing in inets httpd (high 7.0)
- [CVE-2026-48858](https://insights.sbomify.com/CVE-2026-48858/): ftp client PASV response IP not validated against control peer, enabling SSRF and FTP bounce attacks (medium 6.3)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-28808 and fix it if it is affected.

What it is: CVE-2026-28808 is a high-severity missing authorization vulnerability in Erlang OTP, published on 7 Apr 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-28808 in the wild and no public exploit code.

Affected product: Erlang OTP. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-28808/ (Markdown: https://insights.sbomify.com/CVE-2026-28808/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-28808
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-28808
- OSV: https://osv.dev/vulnerability/CVE-2026-28808

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-28808/
Summaries are generated and may contain mistakes; the official description above is the record.