Vulnerability-Lookup

GHSA-GQ94-HF88-G4WV

Vulnerability from github – Published: 2026-06-26 00:32 – Updated: 2026-06-27 21:30

Details

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.

Severity ?

6.5 (Medium)


                  
                    CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N

6.0 (Medium)


                  
                    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

Show details on source website

JSON

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{
  "affected": [],
  "aliases": [
    "CVE-2026-55962"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-287"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-06-25T22:17:02Z",
    "severity": "MODERATE"
  },
  "details": "TLS 1.3 post-handshake authentication (PHA) issue where a server could accept a client\u0027s 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.",
  "id": "GHSA-gq94-hf88-g4wv",
  "modified": "2026-06-27T21:30:28Z",
  "published": "2026-06-26T00:32:06Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-55962"
    },
    {
      "type": "WEB",
      "url": "https://github.com/wolfSSL/wolfssl/pull/10702"
    },
    {
      "type": "WEB",
      "url": "https://www.wolfssl.com/docs/security-vulnerabilities"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N",
      "type": "CVSS_V3"
    },
    {
      "score": "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/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",
      "type": "CVSS_V4"
    }
  ]
}

CVE-2026-55962 (GCVE-0-2026-55962)

Vulnerability from cvelistv5 – Published: 2026-06-25 21:12 – Updated: 2026-06-26 10:31

Title

TLS 1.3 post-handshake authentication: server accepts Finished without client Certificate/CertificateVerify

Summary

Severity ?

6 (Medium)


                        
                          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

CWE

CWE-287 - Improper Authentication

Assigner

wolfSSL

References

URL

Tags

	https://github.com/wolfSSL/wolfssl/pull/10702	patch
	https://www.wolfssl.com/docs/security-vulnerabilities/

Impacted products

	Vendor	Product	Version
	wolfSSL	wolfSSL	Affected: 5.5.4 , ≤ 5.9.1 (semver)

Credits

NVIDIA Project Vanessa

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-55962",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-06-26T10:30:28.816026Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-06-26T10:31:12.017Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "collectionURL": "https://github.com/wolfSSL/wolfssl",
          "defaultStatus": "unaffected",
          "product": "wolfSSL",
          "vendor": "wolfSSL",
          "versions": [
            {
              "lessThanOrEqual": "5.9.1",
              "status": "affected",
              "version": "5.5.4",
              "versionType": "semver"
            }
          ]
        }
      ],
      "credits": [
        {
          "lang": "en",
          "type": "finder",
          "value": "NVIDIA Project Vanessa"
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "supportingMedia": [
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              "type": "text/html",
              "value": "\u003cp\u003eTLS 1.3 post-handshake authentication (PHA) issue where a server could accept a client\u0027s 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.\u003c/p\u003e"
            }
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        }
      ],
      "metrics": [
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          "cvssV4_0": {
            "Automatable": "NOT_DEFINED",
            "Recovery": "NOT_DEFINED",
            "Safety": "NOT_DEFINED",
            "attackComplexity": "LOW",
            "attackRequirements": "PRESENT",
            "attackVector": "NETWORK",
            "baseScore": 6,
            "baseSeverity": "MEDIUM",
            "exploitMaturity": "NOT_DEFINED",
            "privilegesRequired": "LOW",
            "providerUrgency": "NOT_DEFINED",
            "subAvailabilityImpact": "NONE",
            "subConfidentialityImpact": "NONE",
            "subIntegrityImpact": "NONE",
            "userInteraction": "NONE",
            "valueDensity": "NOT_DEFINED",
            "vectorString": "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",
            "version": "4.0",
            "vulnAvailabilityImpact": "NONE",
            "vulnConfidentialityImpact": "NONE",
            "vulnIntegrityImpact": "HIGH",
            "vulnerabilityResponseEffort": "NOT_DEFINED"
          },
          "format": "CVSS",
          "scenarios": [
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              "lang": "en",
              "value": "GENERAL"
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      "problemTypes": [
        {
          "descriptions": [
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              "cweId": "CWE-287",
              "description": "CWE-287 Improper Authentication",
              "lang": "en",
              "type": "CWE"
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          ]
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      ],
      "providerMetadata": {
        "dateUpdated": "2026-06-25T21:12:38.074Z",
        "orgId": "50d2cd11-d01a-48ed-9441-5bfce9d63b27",
        "shortName": "wolfSSL"
      },
      "references": [
        {
          "tags": [
            "patch"
          ],
          "url": "https://github.com/wolfSSL/wolfssl/pull/10702"
        },
        {
          "url": "https://www.wolfssl.com/docs/security-vulnerabilities/"
        }
      ],
      "source": {
        "discovery": "UNKNOWN"
      },
      "title": "TLS 1.3 post-handshake authentication: server accepts Finished without client Certificate/CertificateVerify",
      "x_generator": {
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  "cveMetadata": {
    "assignerOrgId": "50d2cd11-d01a-48ed-9441-5bfce9d63b27",
    "assignerShortName": "wolfSSL",
    "cveId": "CVE-2026-55962",
    "datePublished": "2026-06-25T21:12:38.074Z",
    "dateReserved": "2026-06-17T22:10:55.453Z",
    "dateUpdated": "2026-06-26T10:31:12.017Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

Sightings

Author	Source	Type	Date

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

Action not permitted

GHSA-GQ94-HF88-G4WV

CVE-2026-55962 (GCVE-0-2026-55962)

Tags

Sightings

Nomenclature