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VulnerabilityPublished Updated

CVE-2026-55962: Wolfssl · TLS 1.3 post-handshake authentication (PHA) issue where a server could accept a client's Finished message without the client having sent a

Affects wolfsslSource GCVE Database

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Not known to be exploited · CVSS 6.5 Medium.

Data as of 30 Oct 2026, 06:59 UTC

CVSS 3.1 base score
6.5Medium
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.2% chance of exploitation in 30 days – higher than 14% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 25 Jun 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 29 Oct 2026.

What to do

Affected software

ProductAffectedFixed in
Ubuntu 26.10wolfsslpkg:deb/ubuntu/wolfssl?arch=source&distro=stonkingOther threatsAffected
  • =5.9.1-0.1
  • =5.9.2-1
Fixed in–
Ubuntu 26.04 LTSwolfsslpkg:deb/ubuntu/wolfssl?arch=source&distro=resoluteOther threatsAffected
  • 5.7.2-0.1 – 5.9.1-0.1
4 affected builds
Fixed in–
Ubuntu 25.10wolfsslpkg:deb/ubuntu/wolfssl?arch=source&distro=questingOther threatsAffected
  • =5.7.2-0.1
Fixed in–
Ubuntu 24.04 LTSwolfsslpkg:deb/ubuntu/wolfssl?arch=source&distro=nobleOther threatsAffected
  • 5.5.4-2 – 5.6.6-1.3build1
6 affected builds
Fixed in–
Ubuntu 22.04 LTSwolfsslpkg:deb/ubuntu/wolfssl?arch=source&distro=jammyOther threatsAffected
  • 4.6.0-3 – 5.2.0-2
5 affected builds
Fixed in–
Ubuntu 20.04 LTSwolfsslpkg:deb/ubuntu/wolfssl?arch=source&distro=focalOther threatsAffected
  • 4.1.0+dfsg-2 – 4.3.0+dfsg-2
5 affected builds
Fixed in–

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

Until an official fix is available, avoid enabling post-handshake authentication on wolfSSL TLS 1.3 servers or disable client certificate requests after the handshake. Monitor vendor communications for patches or updates addressing this issue.

Description

A vulnerability in wolfSSL's TLS 1.3 post-handshake authentication (PHA) allows a server to accept a client's Finished message without the client sending the required Certificate and CertificateVerify messages when PHA is enabled. This issue arises because an exemption meant only for the initial handshake was incorrectly applied during post-handshake CertificateRequest. Only TLS 1.3 servers built with PHA support and configured to request client certificates after the handshake are affected. Clients and servers not using PHA are not impacted.

References

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