CVE-2026-11703 - wolfSSL TLS resumption SNI ALPN binding bypass

CVE-2026-11703 - wolfSSL TLS resumption SNI ALPN binding bypass - High - 2026-06-25

Business risk: Cached client-authentication state can cross virtual-host boundaries and bypass stricter authentication policy.

Root cause: Stateful session-ID resumption skipped the SNI/ALPN binding check that ticket-based resumption performed.

Affected versions

  • Vulnerable: wolfSSL builds before the fix when stateful session-ID resumption is used across virtual hosts with different SNI/ALPN or client-auth policy.
  • Fixed / safe target: Upgrade to a wolfSSL build containing PR 10489 or later and partition/validate session caches by SNI and ALPN.
  • CVSS: 7.5 (High)

Exact vulnerable code pattern

wolfSSL_CTX_set_session_cache_mode(ctx, SSL_SESS_CACHE_SERVER);
serve_tls_connection(shared_ctx, client);

Fixed / mitigated code pattern

set_session_cache_key(current_sni, current_alpn, client_auth_policy_id);
if (!session_binding_matches(session, current_sni, current_alpn)) {
    wolfSSL_set_session(ssl, NULL);
}

Step-by-step integration guide

  1. Inventory wolfSSL packages, vendored source, submodules, and embedded SDKs.
  2. Upgrade to the vendor-fixed build and rebuild static consumers.
  3. Add protocol regression/fuzz coverage for the affected path.
  4. Deploy patched firmware/images and retire vulnerable artifacts.
  5. Document temporary network controls used during rollout.

Alternative mitigations

  • Block untrusted traffic to affected protocol endpoints.
  • Disable the affected protocol feature where possible.
  • Run affected services with process sandboxing and rate limits.

Detection signature

rg -n "wolfSSL|WOLFSSL_VERSION|libwolfssl|DTLS|ALPN|SNI|X509" .

Copy-paste skill block

Model context: this prompt was generated by GPT 5.5 Extra High reasoning.

Remediate CVE-2026-11703: wolfSSL TLS resumption SNI ALPN binding bypass.

Required output:
- A reviewer-ready PR with dependency/config/code changes, tests, and deployment notes; or
- TRIAGE.md if the affected runtime is outside this repository.

Steps:
1. Confirm exposure using the detection signature above.
2. Apply the fixed or mitigated pattern.
3. Add or run a regression test for the exploit shape.
4. Record commands, versions, and residual risk in the PR body.

Boundaries:
- Scope only CVE-2026-11703 and directly related hardening.
- Do not run destructive exploit payloads against production.
- Preserve existing behavior except for the vulnerable path.

Tags and revenue routing

  • Keywords: cve, wolfssl, tls, c, memory-safety, sellable_to_iot, zero_day_gold, high
  • Affected tech stack: c/cpp
  • Revenue tags: sellable_to_iot, zero_day_gold

References