OpenSSL Security Advisory

[Tomas Mraz]

OpenSSL Security Advisory [30th September 2025]
===============================================

Out-of-bounds read & write in RFC 3211 KEK Unwrap (CVE-2025-9230)
=================================================================

Severity: Moderate

Issue summary: An application trying to decrypt CMS messages encrypted using
password based encryption can trigger an out-of-bounds read and write.

Impact summary: This out-of-bounds read may trigger a crash which leads to
Denial of Service for an application. The out-of-bounds write can cause
a memory corruption which can have various consequences including
a Denial of Service or Execution of attacker-supplied code.

Although the consequences of a successful exploit of this vulnerability
could be severe, the probability that the attacker would be able to
perform it is low. Besides, password based (PWRI) encryption support in CMS
messages is very rarely used. For that reason the issue was assessed as
Moderate severity according to our Security Policy.

The FIPS modules in 3.5, 3.4, 3.3, 3.2, 3.1 and 3.0 are not affected by this
issue, as the CMS implementation is outside the OpenSSL FIPS module
boundary.

OpenSSL 3.5, 3.4, 3.3, 3.2, 3.0, 1.1.1 and 1.0.2 are vulnerable to this issue.

OpenSSL 3.5 users should upgrade to OpenSSL 3.5.4.

OpenSSL 3.4 users should upgrade to OpenSSL 3.4.3.

OpenSSL 3.3 users should upgrade to OpenSSL 3.3.5.

OpenSSL 3.2 users should upgrade to OpenSSL 3.2.6.

OpenSSL 3.0 users should upgrade to OpenSSL 3.0.18.

OpenSSL 1.1.1 users should upgrade to OpenSSL 1.1.1zd.
(premium support customers only)

OpenSSL 1.0.2 users should upgrade to OpenSSL 1.0.2zm.
(premium support customers only)

This issue was reported on 9th August 2025 by Stanislav Fort (Aisle Research).
The fix was developed by Stanislav Fort (Aisle Research) and Viktor Dukhovni.


Timing side-channel in SM2 algorithm on 64 bit ARM (CVE-2025-9231)
=================================================================

Severity: Moderate

Issue summary: A timing side-channel which could potentially allow remote
recovery of the private key exists in the SM2 algorithm implementation on 64 bit
ARM platforms.

Impact summary: A timing side-channel in SM2 signature computations on 64 bit
ARM platforms could allow recovering the private key by an attacker.

While remote key recovery over a network was not attempted by the reporter,
timing measurements revealed a timing signal which may allow such an attack.

OpenSSL does not directly support certificates with SM2 keys in TLS, and so
this CVE is not relevant in most TLS contexts. However, given that it is
possible to add support for such certificates via a custom provider, coupled
with the fact that in such a custom provider context the private key may be
recoverable via remote timing measurements, we consider this to be a Moderate
severity issue.

The FIPS modules in 3.5, 3.4, 3.3, 3.2, 3.1 and 3.0 are not affected by this
issue, as SM2 is not an approved algorithm.

OpenSSL 3.1, 3.0, 1.1.1 and 1.0.2 are not vulnerable to this issue.

OpenSSL 3.5, 3.4, 3.3, and 3.2 are vulnerable to this issue.

OpenSSL 3.5 users should upgrade to OpenSSL 3.5.4.

OpenSSL 3.4 users should upgrade to OpenSSL 3.4.3.

OpenSSL 3.3 users should upgrade to OpenSSL 3.3.5.

OpenSSL 3.2 users should upgrade to OpenSSL 3.2.6.

This issue was reported on 18th August 2025 by Stanislav Fort (Aisle Research)
The fix was developed by Stanislav Fort.

Out-of-bounds read in HTTP client no_proxy handling (CVE-2025-9232)
===================================================================

Severity: Low

Issue summary: An application using the OpenSSL HTTP client API functions may
trigger an out-of-bounds read if the "no_proxy" environment variable is set and
the host portion of the authority component of the HTTP URL is an IPv6 address.

Impact summary: An out-of-bounds read can trigger a crash which leads to
Denial of Service for an application.

The OpenSSL HTTP client API functions can be used directly by applications
but they are also used by the OCSP client functions and CMP (Certificate
Management Protocol) client implementation in OpenSSL. However the URLs used
by these implementations are unlikely to be controlled by an attacker.

In this vulnerable code the out of bounds read can only trigger a crash.
Furthermore the vulnerability requires an attacker-controlled URL to be
passed from an application to the OpenSSL function and the user has to have
a "no_proxy" environment variable set. For the aforementioned reasons the
issue was assessed as Low severity.

The vulnerable code was introduced in the following patch releases:
3.0.16, 3.1.8, 3.2.4, 3.3.3, 3.4.0 and 3.5.0.

The FIPS modules in 3.5, 3.4, 3.3, 3.2, 3.1 and 3.0 are not affected by this
issue, as the HTTP client implementation is outside the OpenSSL FIPS module
boundary.

OpenSSL 3.5, 3.4, 3.3, 3.2 and 3.0 are vulnerable to this issue.

OpenSSL 1.1.1 and 1.0.2 are not affected by this issue.

OpenSSL 3.5 users should upgrade to OpenSSL 3.5.4.

OpenSSL 3.4 users should upgrade to OpenSSL 3.4.3.

OpenSSL 3.3 users should upgrade to OpenSSL 3.3.5.

OpenSSL 3.2 users should upgrade to OpenSSL 3.2.6.

OpenSSL 3.0 users should upgrade to OpenSSL 3.0.18.

This issue was reported on 16th August 2025 by Stanislav Fort (Aisle Research).
The fix was developed by Stanislav Fort (Aisle Research).

General Advisory Notes
======================

URL for this Security Advisory:
https://openssl-library.org/news/secadv/20250930.txt

Note: the online version of the advisory may be updated with additional details
over time.

For details of OpenSSL severity classifications please see:
https://openssl-library.org/policies/general/security-policy/