CVE-2026-12151
ADVISORY - githubSummary
Impact
The undici WebSocket client enforces maxPayloadSize on the cumulative byte count of fragments in a message but does not enforce a limit on the number of fragments. A malicious WebSocket server can stream many small or empty continuation frames that each pass per-frame and cumulative-size validation, collectively 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(...)) or the WebSocketStream API that can be induced to connect to an attacker-controlled or compromised WebSocket endpoint.
All releases starting at undici 6.17.0 are affected.
Patches
Upgrade to undici v6.27.0, v7.28.0 or v8.5.0.
Workarounds
No workaround is available. The fix must be applied through an upgrade.
Common Weakness Enumeration (CWE)
Allocation of Resources Without Limits or Throttling
GitHub
CVSS SCORE
7.5high| Package | Type | OS Name | OS Version | Affected Ranges | Fix Versions |
|---|---|---|---|---|---|
| undici | npm | - | - | <6.27.0 | 6.27.0 |
| undici | npm | - | - | >=7.0.0,<7.28.0 | 7.28.0 |
| undici | npm | - | - | >=8.0.0,<8.5.0 | 8.5.0 |
CVSS:3 Severity and metrics
The CVSS metrics represent different qualitative aspects of a vulnerability that impact the overall score, as defined by the CVSS Specification.
The vulnerable component is bound to the network stack, but the attack is limited at the protocol level to a logically adjacent topology. This can mean an attack must be launched from the same shared physical (e.g., Bluetooth or IEEE 802.11) or logical (e.g., local IP subnet) network, or from within a secure or otherwise limited administrative domain (e.g., MPLS, secure VPN to an administrative network zone). One example of an Adjacent attack would be an ARP (IPv4) or neighbor discovery (IPv6) flood leading to a denial of service on the local LAN segment (e.g., CVE-2013-6014).
Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success when attacking the vulnerable component.
The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files of the vulnerable system to carry out an attack.
The vulnerable system can be exploited without interaction from any user.
An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
There is no loss of confidentiality.
There is no loss of trust or accuracy within the impacted component.
There is a total loss of availability, resulting in the attacker being able to fully deny access to resources in the impacted component; this loss is either sustained (while the attacker continues to deliver the attack) or persistent (the condition persists even after the attack has completed). Alternatively, the attacker has the ability to deny some availability, but the loss of availability presents a direct, serious consequence to the impacted component.
Debian
-
Ubuntu
-
CVSS SCORE
N/AmediumRed Hat
3.9
CVSS SCORE
7.5highChainguard
CGA-25v4-996r-f3gh
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minimos
MINI-9r4w-3fwx-q69p
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minimos
MINI-gxfr-rpwv-95wf
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minimos
MINI-v9xx-rqpr-v895
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