CVE-2026-105113 in Nezha
Summary
by MITRE • 10/03/2026
Nezha Dashboard from 1.8.0 before 2.3.13 contains an improper locking vulnerability where a non-deferred mutex unlock leaks on a nil-map panic path. Any authenticated non-admin member can issue four notification API calls to permanently deadlock the alerting subsystem, then exhaust memory with blocking requests.
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Analysis
by VulDB Data Team • 10/03/2026
The Nezha Dashboard software versions ranging from 1.8.0 up to but not including 2.3.13 contain a critical concurrency control flaw classified as an improper locking vulnerability. This defect manifests specifically within the alerting subsystem, where the application fails to properly manage mutex locks during error handling paths. The core technical issue arises when a nil-map panic occurs in conjunction with non-deferred mutex operations. In standard Go programming practices, it is common practice to use deferred function calls to ensure that resource cleanup and lock releases occur regardless of whether a function exits normally or due to an exception. However, in this specific code path, the unlock operation for the mutex guarding the alerting state is not deferred. Consequently, if the execution flow encounters a nil-map panic before reaching the explicit unlock statement, the mutex remains locked indefinitely. This creates a permanent deadlock condition within the subsystem responsible for processing and dispatching alerts.
The operational impact of this vulnerability allows any authenticated user with non-administrator privileges to disrupt service availability through a denial-of-service attack vector. An attacker can exploit this flaw by issuing four specific notification API calls that trigger the vulnerable code path involving the nil-map panic. Once these requests are processed, the alerting subsystem becomes permanently deadlocked because the mutex is never released due to the unhandled exception bypassing the cleanup logic. Following the initial deadlock, the system continues to accept new blocking requests against this compromised state. Since the thread or goroutine handling these requests remains blocked waiting for a lock that will never be acquired, it consumes memory resources without completing its task. This leads to a gradual but steady exhaustion of available memory on the server hosting the Nezha Dashboard instance.
This vulnerability aligns with CWE-667, which describes improper locking within multi-threaded or concurrent applications, specifically highlighting scenarios where locks are not released in all execution paths. Furthermore, from an offensive security perspective, this exploit technique corresponds to ATT&CK tactic T1499, Endpoint Denial of Service, and more specifically the sub-technique related to resource exhaustion via blocking operations. The ability for a low-privileged user to cause such significant disruption underscores a failure in both input validation and robust error handling mechanisms within the application architecture.
To mitigate this vulnerability, organizations running Nezha Dashboard must upgrade immediately to version 2.3.13 or any later release where the locking mechanism has been corrected. The fix involves ensuring that mutex unlocks are properly deferred so they execute even when panics occur during nil-map access. Additionally, developers should implement defensive programming practices by validating map references before accessing them and handling potential nil-pointer exceptions gracefully rather than allowing them to bypass critical resource management code. Until an upgrade is performed, administrators might consider restricting API access for non-admin users or implementing network-level rate limiting to reduce the risk of rapid successive requests that could trigger this condition more easily.