OpenSSL Security Advisory [16th October 2024]
=============================================

Low-level invalid GF(2^m) parameters lead to OOB memory access (CVE-2024-9143)
==============================================================================

Severity: Low

Issue summary: Use of the low-level GF(2^m) elliptic curve APIs with untrusted
explicit values for the field polynomial can lead to out-of-bounds memory reads
or writes.

Impact summary: Out of bound memory writes can lead to an application crash or
even a possibility of a remote code execution, however, in all the protocols
involving Elliptic Curve Cryptography that we're aware of, either only "named
curves" are supported, or, if explicit curve parameters are supported, they
specify an X9.62 encoding of binary (GF(2^m)) curves that can't represent
problematic input values. Thus the likelihood of existence of a vulnerable
application is low.

In particular, the X9.62 encoding is used for ECC keys in X.509 certificates,
so problematic inputs cannot occur in the context of processing X.509
certificates.  Any problematic use-cases would have to be using an "exotic"
curve encoding.

The affected APIs include: EC_GROUP_new_curve_GF2m(), EC_GROUP_new_from_params(),
and various supporting BN_GF2m_*() functions.

Applications working with "exotic" explicit binary (GF(2^m)) curve parameters,
that make it possible to represent invalid field polynomials with a zero
constant term, via the above or similar APIs, may terminate abruptly as a
result of reading or writing outside of array bounds.  Remote code execution
cannot easily be ruled out.

The FIPS modules in 3.3, 3.2, 3.1 and 3.0 are not affected by this issue.

OpenSSL 3.3, 3.2, 3.1, 3.0, 1.1.1 and 1.0.2 are vulnerable to this issue.

OpenSSL 3.3 users should upgrade to OpenSSL 3.3.3 once it is released.

OpenSSL 3.2 users should upgrade to OpenSSL 3.2.4 once it is released.

OpenSSL 3.1 users should upgrade to OpenSSL 3.1.8 once it is released.

OpenSSL 3.0 users should upgrade to OpenSSL 3.0.16 once it is released.

OpenSSL 1.1.1 users should upgrade to OpenSSL 1.1.1zb once it is released
(premium support customers only).

OpenSSL 1.0.2 users should upgrade to OpenSSL 1.0.2zl once it is released
(premium support customers only).

Due to the low severity of this issue we are not issuing new releases of
OpenSSL at this time. The fix will be included in the next release of each
branch, once it becomes available. The fix is also available in commit
c0d3e4d3 (for 3.3), commit bc7e04d7 (for 3.2), commit fdf67233 (for 3.1)
and commit 72ae83ad (for 3.0) in the OpenSSL git repository. It is available
to premium support customers in commit 8efc0cba (for 1.1.1) and in commit
9d576994 (for 1.0.2).

This issue was reported on 16th September 2024 by Google OSS-Fuzz-Gen.
The fix was developed by Viktor Dukhovni.

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

URL for this Security Advisory:
https://openssl-library.org/news/secadv/20241016.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/