Patch Package OTP 27.3.4.18 Released
Erlang/OTP
otp@REDACTED
Tue Sep 22 10:33:12 CEST 2026
Patch Package: OTP 27.3.4.18
Git Tag: OTP-27.3.4.18
Date: 2026-09-22
Trouble Report Id: OTP-20256, OTP-20272, OTP-20287, OTP-20327,
OTP-20355, OTP-20358, OTP-20365, OTP-20367,
OTP-20371, OTP-20384, OTP-20386, OTP-20388,
OTP-20390
Seq num: CVE-2026-65634, CVE-2026-68956,
CVE-2026-89422, ERIERL-1355, ERIERL-1356,
ERIERL-1363, GH-11338, GH-11344, GH-11534,
GH-11586, GH-11619, GH-SA-qhcm-px9c-rvfh,
PR-11356, PR-11426, PR-11523, PR-11559,
PR-11566, PR-11570, PR-11574, PR-11616,
PR-11632, PR-11638, PR-11641, PR-11651,
PR-11655
System: OTP
Release: 27
Application: asn1-5.3.4.3, compiler-8.6.1.7,
mnesia-4.23.5.5, public_key-1.17.1.6,
ssh-5.2.11.13, ssl-11.2.12.13
Predecessor: OTP 27.3.4.17
Check out the git tag OTP-27.3.4.18, 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
- Fixed a vulnerability where the `max_channels` daemon option was not enforced
for session channels without an active subsystem, allowing a remote
authenticated user to open an infinite number of channels and exhaust server
resources despite the configured limit.
The default value of the max_channels daemon option has been changed from
infinity to 256. Deployments requiring more than 256 simultaneous channels per
connection can restore the previous behavior by setting
`{max_channels, infinity}`.
The default value of the max_sessions daemon option has been changed from
infinity to 1024. Deployments requiring more concurrent SSH connections can
restore the previous behavior by setting `{max_sessions, infinity}`.
Own Id: OTP-20287
Application(s): ssh
Related Id(s): GH-SA-qhcm-px9c-rvfh, PR-11523, CVE-2026-68956
# asn1-5.3.4.3
The asn1-5.3.4.3 application can be applied independently of other applications
on a full OTP 27 installation.
## Fixed Bugs and Malfunctions
- Fixed a denial-of-service attack in asn1, where abnormally large OID
components (arcs) could cause resource exhaustion.
Own Id: OTP-20272
Related Id(s): PR-11655, CVE-2026-65634
- The JER backend will no longer break certain values (true, false, null) when
they are typed as ENUMERATED, they will now be encoded as strings as required
by the standard.
Own Id: OTP-20355
Related Id(s): ERIERL-1355, PR-11559
> #### Full runtime dependencies of asn1-5.3.4.3
>
> erts-14.0, kernel-9.0, stdlib-5.0
# compiler-8.6.1.7
The compiler-8.6.1.7 application can be applied independently of other
applications on a full OTP 27 installation.
## Fixed Bugs and Malfunctions
- In rare circumstances, the type analysis pass of the compiler could run for
many minutes.
Own Id: OTP-20365
Related Id(s): GH-11534, PR-11566
- Certain uses of funs could crash the compiler. For example:
f() ->
F = fun Fn(0) -> 0; Fn(N) -> Fn(N - 1) end,
[F(X) || X <- [1, 2]].
This has been corrected.
Own Id: OTP-20386
Related Id(s): GH-11619, PR-11638
> #### Full runtime dependencies of compiler-8.6.1.7
>
> crypto-5.1, erts-13.0, kernel-8.4, stdlib-6.0
# mnesia-4.23.5.5
The mnesia-4.23.5.5 application can be applied independently of other
applications on a full OTP 27 installation.
## Fixed Bugs and Malfunctions
- Fixed mnesia:force_load_table/1 getting stuck when the remote node becomes
unreachable during table loading. When a network loader is aborted due to
sender node going down and a user has forced a table load, we now retry
loading from disc instead. Additionally, for disc_only_copies tables, the
process actually loading the table is the dets server process, not the mnesia
loader, so it would not receive the abort notification and would hang
indefinitely. Now it correctly receives the notification and aborts table
loading.
Own Id: OTP-20256
Related Id(s): GH-11344, PR-11426
> #### Full runtime dependencies of mnesia-4.23.5.5
>
> erts-9.0, kernel-5.3, stdlib-5.0
# public_key-1.17.1.6
The public_key-1.17.1.6 application can be applied independently of other
applications on a full OTP 27 installation.
## Fixed Bugs and Malfunctions
- Align moduli and pubkey_moduli.hrl to state on OTP-28 and newer.
Own Id: OTP-20367
Related Id(s): PR-11574
> #### Full runtime dependencies of public_key-1.17.1.6
>
> asn1-5.0, crypto-5.0, erts-13.0, kernel-8.0, stdlib-4.0
# ssh-5.2.11.13
The ssh-5.2.11.13 application can be applied independently of other applications
on a full OTP 27 installation.
## Fixed Bugs and Malfunctions
- Fixed a vulnerability where the `max_channels` daemon option was not enforced
for session channels without an active subsystem, allowing a remote
authenticated user to open an infinite number of channels and exhaust server
resources despite the configured limit.
The default value of the max_channels daemon option has been changed from
infinity to 256. Deployments requiring more than 256 simultaneous channels per
connection can restore the previous behavior by setting
`{max_channels, infinity}`.
The default value of the max_sessions daemon option has been changed from
infinity to 1024. Deployments requiring more concurrent SSH connections can
restore the previous behavior by setting `{max_sessions, infinity}`.
Own Id: OTP-20287
Related Id(s): GH-SA-qhcm-px9c-rvfh, PR-11523, CVE-2026-68956
*** POTENTIAL INCOMPATIBILITY ***
- The SSH daemon no longer rejects a `subsystem` request that is preceded by
`env` or `pty-req` request on the same channel.
Own Id: OTP-20371
Related Id(s): ERIERL-1363, GH-11586, PR-11616
> #### Full runtime dependencies of ssh-5.2.11.13
>
> crypto-5.0, erts-14.0, kernel-9.0, public_key-1.6.1, runtime_tools-1.15.1,
> stdlib-5.0, stdlib-6.0
# ssl-11.2.12.13
Note! The ssl-11.2.12.13 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
- Undecodable `certificate_authorities` names are now skipped, as they are just
a hint.
Own Id: OTP-20327
Related Id(s): GH-11338, PR-11356
- Corrected generated keylog information generated from the `keylog_hs` option
in the corner case that it was invoked after the client had reached its
connection state, but the server closed the connection before it reached its
connection state.
Own Id: OTP-20358
Related Id(s): ERIERL-1356, PR-11570
- Fix restart bug for TLS-1.3 session ticket server, introduced by backport
commit in OTP-27.3.4.14, would case a restart to fail due to wrong number of
arguments.
Own Id: OTP-20384
Related Id(s): PR-11632
- Reject unsolicited TLS-1.3 pre_shared_key in client.
Own Id: OTP-20388
Related Id(s): PR-11641, CVE-2026-89422
- Security and robustness hardening returning RFC mandated alert reasons,
narrowing/correcting length checks.
Correct signature algorithm handling that slightly mixed up signature
algorithms and signature algorithms cert in TLS-1.2.
Add missing TLS-1.3 Brainpool groups support. (Not relevant in 27 patch)
Enhanced/corrected documentation and spec errors/deviations.
Own Id: OTP-20390
Related Id(s): PR-11651
> #### Full runtime dependencies of ssl-11.2.12.13
>
> crypto-5.1, 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
Alex Nogueira, ausimian
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