CVE-2025-11933

Published Nov 21, 2025

Last updated 14 days ago

CVSS low 2.3
Tls

Overview

Description
Improper Input Validation in the TLS 1.3 CKS extension parsing in wolfSSL 5.8.2 and earlier on multiple platforms allows a remote unauthenticated attacker to potentially cause a denial-of-service via a crafted ClientHello message with duplicate CKS extensions.
Source
facts@wolfssl.com
NVD status
Analyzed
Products
wolfssl

Risk scores

CVSS 4.0

Type
Secondary
Base score
2.3
Impact score
-
Exploitability score
-
Vector string
CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:L/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Severity
LOW

CVSS 3.1

Type
Primary
Base score
6.5
Impact score
3.6
Exploitability score
2.8
Vector string
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Severity
MEDIUM

Weaknesses

facts@wolfssl.com
CWE-20

Social media

Hype score
Not currently trending

  1. CVE-2025-11933 Improper Input Validation in the TLS 1.3 CKS extension parsing in wolfSSL 5.8.2 and earlier on multiple platforms allows a remote unauthenticated attacker to potentia… https://t.co/Jg2lWROSaI

    @CVEnew

    21 Nov 2025

    272 Impressions

    0 Retweets

    0 Likes

    1 Bookmark

    0 Replies

    0 Quotes

Configurations

Related CVEs

  1. Citrix NetScaler Improper Input Validation Vulnerability•CVE-2026-88771
  2. Citrix NetScaler Improper Restriction of Operations within the Bounds of a Memory Buffer Vulnerability•CVE-2026-88772
  3. When an application enables both OCSP and CRL revocation checking on one WOLFSSL_CTX or certificate manager, wolfSSL skips the CRL check for any peer certificate that carries no Authority Information Access OCSP URL, and accepts a certificate the loaded CRL lists as revoked. The soft-fail policy for a missing responder collapses the OCSP result onto success before the code decides whether the CRL fallback is still needed, so "no responder exists" becomes indistinguishable from "the responder answered good". Affected builds define both HAVE_OCSP and HAVE_CRL: --enable-ocsp --enable-crl directly, and implicitly --enable-all, --enable-distro, --enable-curl, --enable-nginx, --enable-haproxy, --enable-stunnel, --enable-lighty, --enable-wpas, --enable-strongswan, --enable-mosquitto, --enable-jni, --enable-openvpn and --enable-krb. An application is affected only if it calls both wolfSSL_CTX_EnableOCSP() (or wolfSSL_EnableOCSP() / wolfSSL_CertManagerEnableOCSP()) and wolfSSL_CTX_EnableCRL() (or the equivalents) with a CRL loaded; an application that uses OCSP stapling alone through wolfSSL_CTX_EnableOCSPStapling() is not affected, because that sets up a separate OCSP instance. The defect sits in ProcessPeerCerts() and is reachable over TLS 1.0 through TLS 1.3 and DTLS, both on a client verifying a server certificate and on a server verifying a client certificate under mutual or post-handshake authentication. When the skipped check falls on a chain certificate rather than the leaf, the unchecked intermediate is promoted into the certificate manager and stays a trusted signer for every later connection on that context, so an affected long-running process needs its WOLFSSL_CTX torn down and not only its library replaced. All wolfSSL versions from 5.9.2 and earlier are affected; on versions 5.9.1 and 5.9.2 the WOLFSSL_OCSP_CHECKALL configuration fails closed with OCSP_NEED_URL, which leaves wolfSSL_CTX_EnableOCSP() without CHECKALL as the exposed configuration on 5.9.2.•CVE-2026-94417
  4. MatchTrustedPeer ignores the public key used, leading to forged CA clones passing verification. Affected builds are any that enable the macro WOLFSSL_TRUST_PEER_CERT and load CA certificates with wolfSSL_CTX_trust_peer_cert() or wolfSSL_trust_peer_cert(). The peer must know the certificates being loaded to either of those APIs to take advantage of the issue. When OPENSSL_COMPATIBLE_DEFAULTS is also defined this widens the affected API to include all CA certificate loading. Both macros are defined when using autoconf builds such as (nginx, haproxy, stunnel, wpas, apache httpd, hitch, bind, rsyslog, ffmpeg, all, distro). When the certificate is listed as a trusted peer certificate the issue previously allowed for a malicious (D)TLS server to bypass authentication once knowing which CA’s the client would accept. This also affects mutual authentication cases where the client knows which CA’s the server has loaded. If building with any of these configurations and using (D)TLS where the loaded CA’s could be known and authentication of the peer is desired, users should either: update to the latest wolfSSL version, apply the fix patch, or use the configure flag --disable-openssl-compatible-defaults and not load CA’s with wolfSSL_CTX_trust_peer_cert() or wolfSSL_trust_peer_cert() to mitigate the issue.•CVE-2026-93302
  5. A certificate with no dNSName SAN but another SAN type present (e.g. registeredID or iPAddress) bypassed the Subject CN dNSName name-constraint check. The CN-as-DNS fallback was gated on cert->subjectCN != NULL && cert->altNames == NULL && !cert->isCA instead of "no dNSName SAN", so an out-of-scope CN was accepted. This incomplete fix from CVE-2026-6731, leading to the name-constraint check issue, was introduced in wolfSSL version 5.9.2.•CVE-2026-89134

References

Sources include official advisories and independent security research.