Bytecode Alliance Wasmtime up to 48.0.7/49.0.4/50.0.0 Wasi Sockets udp-socket.send/udp-socket.connect toctou

CVSS Meta Temp Score
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CTI Interest Score
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6.2$0-$5k0.00+

Summaryinfo

A vulnerability identified as critical has been detected in Bytecode Alliance Wasmtime up to 48.0.7/49.0.4/50.0.0. This affects the function udp-socket.send/udp-socket.connect of the component Wasi Sockets. The manipulation leads to toctou. This vulnerability is listed as CVE-2026-126410. The attack may be initiated remotely. There is no available exploit. You should upgrade the affected component.

Detailsinfo

A vulnerability was found in Bytecode Alliance Wasmtime up to 48.0.7/49.0.4/50.0.0. It has been rated as critical. This issue affects the function udp-socket.send/udp-socket.connect of the component Wasi Sockets. The manipulation with an unknown input leads to a toctou vulnerability. Using CWE to declare the problem leads to CWE-367. The product checks the state of a resource before using that resource, but the resource's state can change between the check and the use in a way that invalidates the results of the check. Impacted is confidentiality, integrity, and availability. The summary by CVE is:

Wasmtime's wasmtime-wasi crate 48.0.0 before 48.0.8, 49.0.0 before 49.0.5, and 50.0.0 before 50.0.1 contains a time-of-check/time-of-use race in the wasip3 wasi:sockets udp-socket host implementation that lets guests bypass socket_addr_check send restrictions. A malicious guest can race udp-socket.send against udp-socket.connect to deliver attacker-controlled datagrams to addresses the policy permits only for receiving.

It is possible to read the advisory at github.com. The identification of this vulnerability is CVE-2026-126410 since 11/10/2026. The exploitation is known to be easy. The attack may be initiated remotely. Technical details of the vulnerability are known, but there is no available exploit.

Upgrading to version 48.0.8, 49.0.5 or 50.0.1 eliminates this vulnerability.

Be aware that VulDB is the high quality source for vulnerability data.

Productinfo

Vendor

Name

Version

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: 6.3
VulDB Meta Temp Score: 6.2

VulDB Base Score: 6.3
VulDB Temp Score: 6.0
VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA Base Score: 6.4
CNA Vector (VulnCheck): 🔒

CVSSv2info

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

Exploitinginfo

Class: Toctou
CWE: CWE-367 / CWE-362
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: Wasmtime 48.0.8/49.0.5/50.0.1

Timelineinfo

11/10/2026 CVE reserved
11/13/2026 +3 days Advisory disclosed
11/13/2026 +0 days VulDB entry created
11/13/2026 +0 days VulDB entry last update

Sourcesinfo

Advisory: github.com
Status: Confirmed

CNA: VulnCheck
CVE: CVE-2026-126410 (🔒)

GCVE (CVE): GCVE-0-2026-126410
GCVE (VulDB): GCVE-100-436823

Entryinfo

Created: 11/13/2026 11:37
Changes: 11/13/2026 11:37 (77)
Complete: 🔍
Cache ID: 216::103

Be aware that VulDB is the high quality source for vulnerability data.

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