CVE-2026-59993

MEDIUM
MEDIUM Priority: 0.02 BB Relevance: 63/100
Published: 2026-10-30 Modified: 2026-10-30 First seen: 2026-10-30 Status: active

Attack Surface

Network Low Complexity No Auth

CVSS Vector Breakdown

AV: Network
AC: Low
PR: None
UI: Required
S: Unchanged
C: None
I: None
A: High

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.

Weakness Classification (1)

Affected Software (1)

VendorProductVersion
h2o picotls < a06ca417a16f9126808bf5cabe6c5e6e0f16ecae

Bug Bounty Relevance

63 / 100
✓ Network accessible
✓ No authentication
✓ Low complexity

CVSS Score

6.5 / 10.0 v3.1
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H

EPSS — Exploitation Probability

0.25%
Raw Score 0.002470
Percentile 16.1%
Date 2026-10-31

Intelligence Sources

mitre ref →
nvd ref →