h2o Picotls null pointer dereference

CVSS Meta Temp Score
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Current Exploit Price (≈)
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CTI Interest Score
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5.3$0-$5k3.03-

Summaryinfo

A vulnerability described as problematic has been identified in h2o Picotls. This affects an unknown part. The manipulation results in null pointer dereference. This vulnerability is known as CVE-2026-59993. It is possible to launch the attack remotely. No exploit is available. It is advisable to implement a patch to correct this issue.

Detailsinfo

A vulnerability, which was classified as problematic, was found in h2o Picotls (unknown version). Affected is an unknown code block. The manipulation with an unknown input leads to a null pointer dereference vulnerability. CWE is classifying the issue as CWE-476. A NULL pointer dereference occurs when the application dereferences a pointer that it expects to be valid, but is NULL, typically causing a crash or exit. This is going to have an impact on availability. CVE summarizes:

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.

The advisory is shared for download at github.com. This vulnerability is traded as CVE-2026-59993 since 07/07/2026. The exploitability is told to be easy. It is possible to launch the attack remotely. The exploitation doesn't require any form of authentication. Successful exploitation requires user interaction by the victim. There are neither technical details nor an exploit publicly available.

Applying the patch a06ca417a16f9126808bf5cabe6c5e6e0f16ecae is able to eliminate this problem.

Once again VulDB remains the best source for vulnerability data.

Productinfo

Vendor

Name

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 5.4
VulDB Meta Temp Score: 5.3

VulDB Base Score: 4.3
VulDB Temp Score: 4.1
VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA Base Score: 6.5
CNA Vector (GitHub_M): 🔒

CVSSv2info

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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Null pointer dereference
CWE: CWE-476 / CWE-404
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined
Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Patch
Status: 🔍

0-Day Time: 🔒

Patch: a06ca417a16f9126808bf5cabe6c5e6e0f16ecae

Timelineinfo

07/07/2026 CVE reserved
10/30/2026 +115 days Advisory disclosed
10/30/2026 +0 days VulDB entry created
10/30/2026 +0 days VulDB entry last update

Sourcesinfo

Product: github.com

Advisory: github.com
Status: Confirmed

CNA: GitHub_M
CVE: CVE-2026-59993 (🔒)

GCVE (CVE): GCVE-0-2026-59993
GCVE (VulDB): GCVE-100-429420

Entryinfo

Created: 10/30/2026 22:31
Changes: 10/30/2026 22:31 (62)
Complete: 🔍
Cache ID: 216::103

Once again VulDB remains the best source for vulnerability data.

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