What is CVE-2026-55962?
TLS 1.3 post-handshake authentication (PHA) issue where a server could accept a client's Finished message without the client having sent a Certificate and CertificateVerify. The post-handshake-auth exemption that allows an empty/absent peer certificate was only intended for the initial handshake, but it was also being applied while a post-handshake CertificateRequest was still outstanding. The check is now scoped to the initial handshake only: on the server, once a post-handshake CertificateRequest has been sent (certReqCtx is set), a peer certificate and a valid CertificateVerify are required again before the Finished is accepted, with empty-certificate handling following the configured verify mode (FAIL_IF_NO_PEER_CERT) just as during first-handshake client authentication. Only affects TLS 1.3 servers built with post-handshake authentication support (WOLFSSL_POST_HANDSHAKE_AUTH / --enable-postauth, included in --enable-all) that enable WOLFSSL_VERIFY_POST_HANDSHAKE and request a client certificate after the handshake via wolfSSL_request_certificate(). Clients, and servers that do not use post-handshake authentication, are unaffected.
The record classifies CVE-2026-55962 under weakness class CWE-287. Its CVSS v3 base vector states that the flaw is reachable remotely over the network, needs low-privilege credentials, needs no user interaction, and has high impact on integrity. 1 affected-product entry is recorded, across 1 vendor, listed below. The identifier was first published 102 days ago.
Severity and exploitation probability
- CVSS v3.1 base score
- 6.5 — MEDIUM
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N - CVSS v4.0 base score
- 6
CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N - EPSS (FIRST)
- 0.2% probability of exploitation in the next 30 days, higher than 10.1% of all scored CVEs
- CISA KEV
- Not listed in the CISA Known Exploited Vulnerabilities catalog
- Threadlinqs priority
- 3.7/10 — a Threadlinqs composite of the CVSS base score, the EPSS percentile and public exploit availability
- Published
- 2026-06-25, last modified 2026-06-26
Is CVE-2026-55962 being exploited?
It currently carries a trending score of 32 in the Threadlinqs vulnerability feed.
Affected products and versions
- wolfSSL: wolfSSL
How to fix CVE-2026-55962
The record marks a vendor fix as available for CVE-2026-55962. Patch reference: https://github.com/wolfSSL/wolfssl/pull/10702. Vendor advisory: https://www.wolfssl.com/docs/security-vulnerabilities/. Apply the vendor fix referenced above to every affected product listed in this record, then confirm the running version against the vendor advisory.
Threat activity tracking CVE-2026-55962
No threat campaign in the Threadlinqs corpus currently references CVE-2026-55962, in its CVE list or as an indicator. The linkage is recomputed from the live corpus on every daily ingest, so this section fills in as soon as a tracked campaign cites the identifier.
Sources
Enriched from CVE.org, NVD, FIRST EPSS, GitHub Security Advisories. Last verified by Threadlinqs on . This product uses the NVD API but is not endorsed or certified by the NVD.