Listen to this Post
How the CVE Works:
This vulnerability exists within the wolfSSL library’s implementation of TLS 1.3. During the handshake, a client can use a Pre-Shared Key (PSK) for resumption. Part of this process involves sending a “PSK binder,” which is an HMAC value the server must verify. The vulnerable wolfSSL server code compared this received HMAC against the expected value using a standard `memcmp()` or similar non-constant-time function. Differences in the time taken to complete this comparison (based on how many bytes match) could leak information about the secret binder value. A remote attacker capable of precise timing measurements could iteratively probe and potentially forge a valid PSK binder, leading to an unauthorized session resumption or impersonation.
Platform: wolfSSL Library
Version: Specific versions
Vulnerability: Timing Side-Channel
Severity: Medium
date: 2025-11-21
Prediction: Patch 2025-12-18
What Undercode Say:
$ grep -r "PSK binder" ./src/ $ git log --oneline --grep="timing" --grep="constant" --grep="CVE-2025-11932" Check for patch in version: $ ./configure && make && ./tests/unit.test --test tls13
How Exploit:
Attacker measures handshake response times across many connection attempts with crafted binders. Statistical analysis of timing differences reveals correct HMAC bytes incrementally, allowing binder forgery and session compromise.
Protection from this CVE:
Update wolfSSL library. Apply vendor patch implementing constant-time HMAC comparison (e.g., using `ConstantCompare` function). Disable TLS 1.3 PSK resumption if not required.
Impact:
Unauthorized TLS session establishment, potential impersonation of clients or servers using PSK-based authentication.
🎯Let’s Practice Exploiting & Learn Patching For Free:
Sources:
Reported By: nvd.nist.gov
Extra Source Hub:
Undercode
