OTP: Incorrect Authorization
CVE-2026-28808 is a critical-severity incorrect authorization vulnerability in OTP from Erlang, with a CVSS 3.1 base score of 9.8 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. Affected OTP versions: 17.0 and later; 5.10 and later; 07b8f441ca711f9812fad9e9115bab3c3aa92f79 and later. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 0.57% chance of exploitation within 30 days, which is low compared with other CVEs.
Critical severity: a successful attack would have severe impact.
What to do
- Update Erlang/inets to 9.1.0.6 or 9.3.2.4 or 9.6.2, whichever matches your release line, or a later version.
- Update Erlang/otp to 26.2.5.19 or 27.3.4.10 or 28.4.2, whichever matches your release line, or a later version.
- Read the advisory on cna.erlef.org for workarounds and exact fixed builds.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Erlang | OTP | 17.0 and later; 5.10 and later; 07b8f441ca711f9812fad9e9115bab3c3aa92f79 and later | Not stated |
| Red Hat | Red Hat OpenStack Platform 16.2 | Not specified in the record | Not stated |
| Red Hat | Red Hat OpenStack Platform 17.1 | Not specified in the record | Not stated |
| Red Hat | Red Hat OpenStack Platform 18.0 | Not specified in the record | Not stated |
| Erlang | Erlang/inets | 5.10 up to, but not including, 9.1.0.6; after 9.2 up to, but not including, 9.3.2.4; after 9.4 up to, but not including, 9.6.2 | 9.1.0.6, 9.3.2.4, 9.6.2 |
| Erlang | Erlang/otp | 17.0 up to, but not including, 26.2.5.19; 27.0 up to, but not including, 27.3.4.10; 28.0 up to, but not including, 28.4.2 | 26.2.5.19, 27.3.4.10, 28.4.2 |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 4.0 | 8.3 | High | CNA |
| CVSS 3.1 | 9.8 | Critical | NVD |
| CVSS 3.1 | 7.4 | High | CNA |
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.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Incorrect Authorization
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.
How developers prevent this class of flaw
- Divide the product into anonymous, normal, privileged, and administrative areas. Reduce the attack surface by carefully mapping roles with data and functionality. Use role-based access control (RBAC) to enforce the roles at the appropriate boundaries. Note that this approach may not protect against horizontal authorization, i.e., it will not protect a user from attacking others with the same role.
- Ensure that access control checks are performed related to the business logic. These checks may be different than the access control checks that are applied to more generic resources such as files, connections, processes, memory, and database records. For example, a database may restrict access for medical records to a specific database user, but each record might only be intended to be accessible to the patient and the patient's doctor.
- Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. For example, consider using authorization frameworks such as the JAAS Authorization Framework and the OWASP ESAPI Access Control feature.
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: yes, technical impact: partial).
- Record last changed materially (score, affected products, status or references).
References
Advisories
- cna.erlef.org/cves/CVE-2026-28808.htmlMitigation
- github.com/erlang/otp/security/advisories/GHSA-3vhp-h532-mc3fThird Party Advisory
Patches and release notes
Other references
Other vulnerabilities in OTP
- 8.2 High severity
- 9.3 Critical severity
- 7.1 High severity
- 8.2 High severity
- 8.2 High severity
- 8.7 High severity
Recent Incorrect Authorization vulnerabilities
- 7.1 High severity
- 8.1 High severity
- 9.8 Critical severity
- 8.1 High severity
- 8.8 High severity
- 8.8 High severity
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