```
Patch Package:           OTP 27.3.4.12
Git Tag:                 OTP-27.3.4.12
Date:                    2026-05-27
Trouble Report Id:       OTP-20112, OTP-20128, OTP-20129, OTP-20130,
                         OTP-20140, OTP-20141
Seq num:                 CVE-2026-42789, CVE-2026-42790, ERIERL-1314,
                         GH-11088, PR-11079, PR-11089, PR-11123,
                         PR-11124, PR-11125, PR-11136
System:                  OTP
Release:                 27
Application:             compiler-8.6.1.5, inets-9.3.2.5,
                         public_key-1.17.1.3, ssl-11.2.12.8
Predecessor:             OTP 27.3.4.11
```

Check out the git tag OTP-27.3.4.12, and build a full OTP system including
documentation. Apply one or more applications from this build as patches to your
installation using the 'otp_patch_apply' tool. For information on install
requirements, see descriptions for each application version below.

# POTENTIAL INCOMPATIBILITIES

- 'public_key', Adhere to RFC 9525, and remove support for legacy fallback to
  check hostname against subject common name. Also improve error handling
  creating two separate errors for name constraint check for subject names and
  subject alternative names.

  'ssl'. Error handling is slightly changed to better reflect public_key
  behaviour.

  Own Id: OTP-20130  
  Application(s): public_key, ssl  
  Related Id(s): [PR-11124], [CVE-2026-42790]

# compiler-8.6.1.5

The compiler-8.6.1.5 application can be applied independently of other
applications on a full OTP 27 installation.

## Fixed Bugs and Malfunctions

- In rare circumstances, optimization of boolean expressions could invert the
  boolean value.

  Own Id: OTP-20140  
  Related Id(s): [GH-11088], [PR-11089]

> #### Full runtime dependencies of compiler-8.6.1.5
>
> crypto-5.1, erts-13.0, kernel-8.4, stdlib-6.0

# inets-9.3.2.5

The inets-9.3.2.5 application can be applied independently of other applications
on a full OTP 27 installation.

## Fixed Bugs and Malfunctions

- A call to httpd:reload_config/2 now validates the new configuration before
  removing the old one, leaving the server running in case of faulty config,
  instead of putting it in an unrecoverable state.

  Own Id: OTP-20128  
  Related Id(s): ERIERL-1314, [PR-11079]

> #### Full runtime dependencies of inets-9.3.2.5
>
> erts-14.0, kernel-9.0, mnesia-4.12, public_key-1.13, runtime_tools-1.8.14,
> ssl-9.0, stdlib-5.0, stdlib-6.0

# public_key-1.17.1.3

The public_key-1.17.1.3 application can be applied independently of other
applications on a full OTP 27 installation.

## Fixed Bugs and Malfunctions

- OCSP responder certificates are now checked for expiration before being
  accepted as authorized responders. Previously, expired or not-yet-valid
  responder certificates were incorrectly accepted when verifying OCSP
  responses.

  Own Id: OTP-20112  
  Related Id(s): [PR-11136]

- Corrected basic constraint path validation check in accordance to RFC 5280.

  Own Id: OTP-20129  
  Related Id(s): [PR-11123], [CVE-2026-42789]

- 'public_key', Adhere to RFC 9525, and remove support for legacy fallback to
  check hostname against subject common name. Also improve error handling
  creating two separate errors for name constraint check for subject names and
  subject alternative names.

  'ssl'. Error handling is slightly changed to better reflect public_key
  behaviour.

  Own Id: OTP-20130  
  Related Id(s): [PR-11124], [CVE-2026-42790]

  \*\*\* POTENTIAL INCOMPATIBILITY \*\*\*

> #### Full runtime dependencies of public_key-1.17.1.3
>
> asn1-5.0, crypto-5.0, erts-13.0, kernel-8.0, stdlib-4.0

# ssl-11.2.12.8

Note! The ssl-11.2.12.8 application _cannot_ be applied independently of other
applications on an arbitrary OTP 27 installation.

       On a full OTP 27 installation, also the following runtime
       dependency has to be satisfied:
       -- public_key-1.17.1.3 (first satisfied in OTP 27.3.4.12)

## Fixed Bugs and Malfunctions

- 'public_key', Adhere to RFC 9525, and remove support for legacy fallback to
  check hostname against subject common name. Also improve error handling
  creating two separate errors for name constraint check for subject names and
  subject alternative names.

  'ssl'. Error handling is slightly changed to better reflect public_key
  behaviour.

  Own Id: OTP-20130  
  Related Id(s): [PR-11124], [CVE-2026-42790]

  \*\*\* POTENTIAL INCOMPATIBILITY \*\*\*

- Could cause server to terminate a connection without an alert towards a bad
  client.

  Own Id: OTP-20141  
  Related Id(s): [PR-11125]

> #### Full runtime dependencies of ssl-11.2.12.8
>
> crypto-5.0, erts-15.0, inets-5.10.7, kernel-9.0, public_key-1.17.1.3,
> runtime_tools-1.15.1, stdlib-6.0

# Thanks to

Paul Guyot

[CVE-2026-42789]: https://nvd.nist.gov/vuln/detail/CVE-2026-42789
[CVE-2026-42790]: https://nvd.nist.gov/vuln/detail/CVE-2026-42790
[GH-11088]: https://github.com/erlang/otp/issues/11088
[PR-11079]: https://github.com/erlang/otp/pull/11079
[PR-11089]: https://github.com/erlang/otp/pull/11089
[PR-11123]: https://github.com/erlang/otp/pull/11123
[PR-11124]: https://github.com/erlang/otp/pull/11124
[PR-11125]: https://github.com/erlang/otp/pull/11125
[PR-11136]: https://github.com/erlang/otp/pull/11136