CVE-2026-89040: Tencent Mass Service Engine in Cluster (MSEC) path traversal

Severity: critical (CVSS 9.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 1.1% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-09-15 · updated 2026-09-22
Weakness: CWE-22

Description

Tencent Mass Service Engine in Cluster (MSEC) allows a remote, unauthenticated attacker to send a crafted POST request including ../ and gain root access on the target device. An attacker who uploads a webshell can execute arbitrary code as root.

Affected products

Tencent Mass Service Engine in Cluster (MSEC): all versions

References

https://github.com/Tencent/MSEC
https://raw.githubusercontent.com/cisagov/CSAF/develop/csaf_files/IT/white/2026/va-26-258-02.json
https://www.cve.org/CVERecord?id=CVE-2026-89040

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