When initializing an RSA public key from DER or PEM bytes throws an error, the EVPPKEY is double-freed: first in the catch block, then in the deinit. This can lead to a crash on future memory allocations. This double-free manifests when BoringSSL cannot decode the public key from the bytes provided. This vulnerability is addressed in swift-crypto version 4.5.1.

Hello,

CERT/CC published three vulnerability notes on 13 and 14 October 2026 about how open-source TLS/X.509 libraries enforce Name Constraints (RFC 5280 section 4.2.1.10). I reported the findings. This is a summary of public fixes and statuses; it does not announce new CVEs.

https://kb.cert.org/vuls/id/573195 https://kb.cert.org/vuls/id/948176 https://kb.cert.org/vuls/id/410595

The differences fall into four areas: DNS-name comparison (RFC 5280 requires case-insensitive matching), IP addresses (the RFC does not say whether IPv4-mapped IPv6 should be treated as IPv4), URI-authority parsing, and wildcards (the RFC does not define wildcard SAN semantics).

Fixed or merged:

pyca/cryptography CVE-2026-34073, fixed in 46.0.6. DNS constraints were checked against the certificate's SANs but not against the requested peer name. GHSA-m959-cc7f-wv43 rustls/webpki wildcards under permitted subtrees: CVE-2026-93601, fixed in 0.103.12 / 0.104.0-alpha.6 (GHSA-xgp8-3hg3-c2mh). Unsupported URI constraints were accepted: CVE-2026-93600, first fix in 0.103.12 / 0.104.0-alpha.6, excludedSubtrees case completed in 0.103.13 / 0.104.0-alpha.7 (GHSA-965h-392x-2mh5). GnuTLS CVE-2026-3833, fixed in 3.8.13. DNS names and the domain part of rfc822Name constraints compared case-sensitively. Independently co-reported. wolfSSL CVE-2026-5263, fixed in 5.9.1: URI constraints parsed but not enforced. Fragment wildcards (e.g. foo.com): PR 9991, in 5.9.1. Note: VU#948176 cites CVE-2026-3547 for the URI report; that CVE record describes an ALPN parsing issue. AWS-LC wildcard Common Name fallback fixed in 1.71.0 / aws-lc-sys 0.39.0 (GHSA-3jrg-j22w-mpmc, GHSA-394x-vwmw-crm3). The same advisory covers Unicode CN; VU#948176 lists that report as still under coordination. Go crypto/x509 CVE-2026-33810, fixed in Go 1.26.2 (GO-2026-4866, co-credited): case handling in wildcard parent-constraint lookup. OpenSSL URI authority: the userinfo scan for @ ran past /, ? or #. PR #30319; OpenSSL confirmed on 2026-09-10 that it is in all then-supported versions. BoringSSL VU#410595.8 (wildcard vs excluded host) and .12 (trailing-dot DNS names) fixed upstream in commit 5774eca (2026-03-04), legacy crypto/x509 path.

Open, disputed or declined (per the notes):

Go two reports in triage; IPv4-mapped IPv6 report not accepted as meeting the security bar OpenSSL userinfo-colon report in triage BoringSSL .9 accepted (upstream change b84dc60, 2026-05-05), .10 disputed, .11 declined Mozilla NSS IP-address report under coordination LibreSSL wildcard report under coordination s2n-tls Common Name fallback report in triage Mbed TLS non-critical Name Constraints not enforced in the reported configuration; vendor treats support as a feature request, reporter's concern disputed

Conditions, according to CERT/CC: an attacker needs a trusted signature over chosen certificate fields, an affected validation path must be reachable, and the application must use the accepted name for authorization. The notes do not report exploitation. Using one of these libraries does not by itself mean a product reaches an affected path.

No test vectors are published for anything not fixed.

Per-finding status with dated sources: https://paperlock.org/findings/

Regards, Oleh Konko 1seal - https://1seal.org/research/

Attack Vector: Local

Vendor: OpenSSL, LibreSSL, BoringSSL

Versions Affected: OpenSSL 1.0.1u and previous versions LibreSSL (pre 6.0 errata 16, pre 5.9 errata 33) BoringSSL pre November 2015

Description: The signing function in crypto/ecdsa/ecdsaossl.c in certain OpenSSL versions and forks is vulnerable to timing attacks when signing with the standardized elliptic curve P-256 despite featuring constant-time curve operations and modular inversion. A software defect omits setting the BNFLGCONSTTIME flag for nonces, failing to take a secure code path in the BNmodinverse method and therefore resulting in a cache-timing attack vulnerability. A malicious user with local access can recover ECDSA P-256 private keys.

Mitigation: Users of OpenSSL with the affected versions should apply the patch available in the manuscript at [1].

Users of LibreSSL should apply the official patch from OpenBSD [2,3].

Users of BoringSSL should upgrade to a more recent version.

Credit: This issue was reported by Cesar Pereida García and Billy Brumley (Tampere University of Technology).

Timeline: 19 Dec 2016 Disclosure to OpenSSL, LibreSSL, BoringSSL security teams 29 Dec 2016 Embargo lifted

References: [1] http://ia.cr/2016/1195 [2] https://ftp.openbsd.org/pub/OpenBSD/patches/5.9/common/033libcrypto.patch.sig [3] https://ftp.openbsd.org/pub/OpenBSD/patches/6.0/common/016libcrypto.patch.sig

- Cesar