undici up to 8.4.x maxPayloadSize Feature resource consumption

CVSS Meta Temp Score
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CTI Interest Score
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6.3$0-$5k1.79-

Summaryinfo

A vulnerability labeled as problematic has been found in undici up to 8.4.x. Affected is an unknown function of the component maxPayloadSize Feature. Such manipulation leads to resource consumption. This vulnerability is traded as CVE-2026-9675. The attack may be launched remotely. There is no exploit available. The affected component should be upgraded.

Detailsinfo

A vulnerability was found in undici up to 8.4.x and classified as problematic. Affected by this issue is an unknown part of the component maxPayloadSize Feature. The manipulation with an unknown input leads to a resource consumption vulnerability. Using CWE to declare the problem leads to CWE-400. The product does not properly control the allocation and maintenance of a limited resource, thereby enabling an actor to influence the amount of resources consumed, eventually leading to the exhaustion of available resources. Impacted is availability. CVE summarizes:

Impact: The undici WebSocket client enforces maxPayloadSize per-frame but does not enforce the cumulative size of fragmented uncompressed messages. A malicious WebSocket server can stream many small fragments that each pass per-frame validation but collectively exceed the configured limit, causing unbounded memory growth in the client process. The result is memory exhaustion and a denial of service. Affected applications are those using the undici WebSocket client (new WebSocket(...)) that can be induced to connect to an attacker-controlled or compromised WebSocket endpoint. This is a regression specific to undici 8.1.0. The 6.25.0 line shipped the equivalent cumulative check from the start and is unaffected. The 7.x line never had the maxPayloadSize feature and is also unaffected. Patches: Upgrade to undici >= 8.5.0. Workarounds: No workaround is available. The fix must be applied through an upgrade.

The weakness was shared by Str1ckl4nd, lzhou1110 and Zyy0530. The advisory is available at github.com. This vulnerability is handled as CVE-2026-9675 since 05/27/2026. The exploitation is known to be easy. The attack may be launched remotely. No form of authentication is required for exploitation. The technical details are unknown and an exploit is not available. This vulnerability is assigned to T1499 by the MITRE ATT&CK project.

Upgrading to version 8.5.0 eliminates this vulnerability.

The vulnerability is also documented in the vulnerability database at EUVD (EUVD-2026-37752). If you want to get best quality of vulnerability data, you may have to visit VulDB.

Productinfo

Name

Version

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

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 (openjs): 🔒

CVSSv2info

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

Exploitinginfo

Class: Resource consumption
CWE: CWE-400 / 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: undici 8.5.0

Timelineinfo

05/27/2026 CVE reserved
06/17/2026 +21 days Advisory disclosed
06/17/2026 +0 days VulDB entry created
06/17/2026 +0 days VulDB entry last update

Sourcesinfo

Advisory: github.com
Researcher: Str1ckl4nd, lzhou1110, Zyy0530
Status: Confirmed

CVE: CVE-2026-9675 (🔒)
GCVE (CVE): GCVE-0-2026-9675
GCVE (VulDB): GCVE-100-372074
EUVD: 🔒

Entryinfo

Created: 06/17/2026 18:51
Updated: 06/17/2026 20:41
Changes: 06/17/2026 18:51 (64), 06/17/2026 20:41 (1)
Complete: 🔍
Cache ID: 216::103

If you want to get best quality of vulnerability data, you may have to visit VulDB.

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