CVE-2026-59993

Full vulnerability record from the local CVENow database.

Description

Picotls is a TLS protocol library that allows users select different crypto backends based on their use case. In affected revisions through 44bc503, when picotls is used as a `client-side TLS stack`, a peer can send a `HelloRetryRequest` followed by a `spoofed Hello message` that causes a null-pointer dereference. This can terminate the consuming process, including a process performing other work, resulting in denial of service. This issue is fixed in commit a06ca41.

Severity

MEDIUM

CVSS score

6.5 (v3.1)

Vulnerability status

Deferred

Source identifier

[email protected]

Published

2026-10-30 21:17:13.067000

Last modified

2026-10-30 21:17:13.193000

View original CVE JSON

{
  "id": "CVE-2026-59993",
  "sourceIdentifier": "[email protected]",
  "published": "2026-10-30T21:17:13.067",
  "lastModified": "2026-10-30T21:17:13.193",
  "vulnStatus": "Deferred",
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "Picotls is a TLS protocol library that allows users select different crypto backends based on their use case. In affected revisions through 44bc503, when picotls is used as a `client-side TLS stack`, a peer can send a `HelloRetryRequest` followed by a `spoofed Hello message` that causes a null-pointer dereference. This can terminate the consuming process, including a process performing other work, resulting in denial of service. This issue is fixed in commit a06ca41."
    }
  ],
  "affected": [
    {
      "source": "[email protected]",
      "affectedData": [
        {
          "vendor": "h2o",
          "product": "picotls",
          "versions": [
            {
              "version": "< a06ca417a16f9126808bf5cabe6c5e6e0f16ecae",
              "status": "affected"
            }
          ]
        }
      ]
    }
  ],
  "metrics": {
    "cvssMetricV31": [
      {
        "source": "[email protected]",
        "type": "Secondary",
        "cvssData": {
          "version": "3.1",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H",
          "baseScore": 6.5,
          "baseSeverity": "MEDIUM",
          "attackVector": "NETWORK",
          "attackComplexity": "LOW",
          "privilegesRequired": "NONE",
          "userInteraction": "REQUIRED",
          "scope": "UNCHANGED",
          "confidentialityImpact": "NONE",
          "integrityImpact": "NONE",
          "availabilityImpact": "HIGH"
        },
        "exploitabilityScore": 2.8,
        "impactScore": 3.6
      }
    ]
  },
  "weaknesses": [
    {
      "source": "[email protected]",
      "type": "Primary",
      "description": [
        {
          "lang": "en",
          "value": "CWE-476"
        }
      ]
    }
  ],
  "references": [
    {
      "url": "https://github.com/h2o/picotls/commit/a06ca417a16f9126808bf5cabe6c5e6e0f16ecae",
      "source": "[email protected]"
    },
    {
      "url": "https://github.com/h2o/picotls/pull/608",
      "source": "[email protected]"
    },
    {
      "url": "https://github.com/h2o/picotls/security/advisories/GHSA-2xcv-h2pg-m99c",
      "source": "[email protected]"
    }
  ]
}