h3js h3 up to 2.0.1-rc.17 Cookie setChunkedCookie/deleteChunkedCookie infinite loop

CVSS Meta Temp Score
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CTI Interest Score
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6.3$0-$5k1.25+

Summaryinfo

A vulnerability classified as problematic has been found in h3js h3 up to 2.0.1-rc.17. This impacts the function setChunkedCookie/deleteChunkedCookie of the component Cookie Handler. The manipulation leads to infinite loop. This vulnerability is traded as CVE-2026-86250. It is possible to initiate the attack remotely. There is no exploit available.

Detailsinfo

A vulnerability was found in h3js h3 up to 2.0.1-rc.17. It has been rated as problematic. This issue affects the function setChunkedCookie/deleteChunkedCookie of the component Cookie Handler. The manipulation with an unknown input leads to a infinite loop vulnerability. Using CWE to declare the problem leads to CWE-835. The product contains an iteration or loop with an exit condition that cannot be reached, i.e., an infinite loop. Impacted is availability. The summary by CVE is:

h3 versions before 2.0.1-rc.18 fail to validate the chunk count parsed from user-controlled cookie values in setChunkedCookie() and deleteChunkedCookie() functions. Attackers can send a crafted cookie header with an extremely large chunk count to trigger an O(n²) cleanup loop that hangs the server process.

It is possible to read the advisory at github.com. The identification of this vulnerability is CVE-2026-86250 since 09/06/2026. The exploitation is known to be easy. The attack may be initiated remotely. No form of authentication is needed for a successful exploitation. Technical details of the vulnerability are known, but there is no available exploit. The attack technique deployed by this issue is T1499 according to MITRE ATT&CK.

Upgrading to version 2.0.1-rc.18 eliminates this vulnerability.

The vulnerability is also documented in the vulnerability database at EUVD (EUVD-2026-72106). Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

Productinfo

Vendor

Name

Version

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA CVSS-B Score: 🔒
CNA CVSS-BT Score: 🔒
CNA Vector: 🔒

CVSSv3info

VulDB Meta Base Score: 6.4
VulDB Meta Temp Score: 6.3

VulDB Base Score: 5.3
VulDB Temp Score: 5.1
VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA Base Score: 7.5
CNA Vector (VulnCheck): 🔒

CVSSv2info

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

Exploitinginfo

Class: Infinite loop
CWE: CWE-835 / 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: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: h3 2.0.1-rc.18

Timelineinfo

09/06/2026 Advisory disclosed
09/06/2026 +0 days CVE reserved
09/06/2026 +0 days VulDB entry created
09/06/2026 +0 days VulDB entry last update

Sourcesinfo

Product: github.com

Advisory: github.com
Status: Confirmed

CVE: CVE-2026-86250 (🔒)
GCVE (CVE): GCVE-0-2026-86250
GCVE (VulDB): GCVE-100-399419
EUVD: 🔒

Entryinfo

Created: 09/06/2026 14:21
Updated: 09/06/2026 16:57
Changes: 09/06/2026 14:21 (77), 09/06/2026 16:57 (1)
Complete: 🔍
Cache ID: 216::103

Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

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