CVE-2026-43981: CWE-362: Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition') in xyproto algernon
CVE-2026-43981 is a race condition vulnerability in the xyproto algernon web server versions prior to 1.17.6. The issue arises because a synchronization mutex protecting a shared Lua state is released too early, allowing concurrent requests to corrupt the Lua virtual machine state. This vulnerability has a high severity with a CVSS score of 8.2. The vulnerability is fixed in version 1.17.6 of algernon.
AI Analysis
Technical Summary
Algernon, a pure-Go web server, had a concurrency flaw in versions before 1.17.6 where the sync.RWMutex guarding LoadCommonFunctions was released before calls to L.Push() and L.PCall() on the Lua state. Since the Lua state (gopher-lua's LState) is not safe for concurrent goroutine access, this leads to race conditions and corruption of the Lua VM under concurrent requests. The Go race detector confirms this behavior under moderate concurrency. This issue is tracked as CWE-362 (Concurrent Execution using Shared Resource with Improper Synchronization) and is resolved in algernon 1.17.6.
Potential Impact
Exploitation of this vulnerability can cause corruption of the Lua virtual machine state during concurrent request processing, potentially leading to application instability, crashes, or unexpected behavior in the algernon web server. The CVSS score of 8.2 indicates a high impact, but there is no indication of privilege escalation or remote code execution. No known exploits in the wild have been reported.
Mitigation Recommendations
This vulnerability is fixed in algernon version 1.17.6. Users should upgrade to version 1.17.6 or later to remediate this issue. Patch status is not explicitly confirmed in the vendor advisory, but the description states the issue is fixed in 1.17.6, indicating an official fix is available.
CVE-2026-43981: CWE-362: Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition') in xyproto algernon
Description
CVE-2026-43981 is a race condition vulnerability in the xyproto algernon web server versions prior to 1.17.6. The issue arises because a synchronization mutex protecting a shared Lua state is released too early, allowing concurrent requests to corrupt the Lua virtual machine state. This vulnerability has a high severity with a CVSS score of 8.2. The vulnerability is fixed in version 1.17.6 of algernon.
CVSS v4.0
Score 8.2high
Affected software
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Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
Algernon, a pure-Go web server, had a concurrency flaw in versions before 1.17.6 where the sync.RWMutex guarding LoadCommonFunctions was released before calls to L.Push() and L.PCall() on the Lua state. Since the Lua state (gopher-lua's LState) is not safe for concurrent goroutine access, this leads to race conditions and corruption of the Lua VM under concurrent requests. The Go race detector confirms this behavior under moderate concurrency. This issue is tracked as CWE-362 (Concurrent Execution using Shared Resource with Improper Synchronization) and is resolved in algernon 1.17.6.
Potential Impact
Exploitation of this vulnerability can cause corruption of the Lua virtual machine state during concurrent request processing, potentially leading to application instability, crashes, or unexpected behavior in the algernon web server. The CVSS score of 8.2 indicates a high impact, but there is no indication of privilege escalation or remote code execution. No known exploits in the wild have been reported.
Mitigation Recommendations
This vulnerability is fixed in algernon version 1.17.6. Users should upgrade to version 1.17.6 or later to remediate this issue. Patch status is not explicitly confirmed in the vendor advisory, but the description states the issue is fixed in 1.17.6, indicating an official fix is available.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- GitHub_M
- Date Reserved
- 2026-05-04T20:24:31.916Z
- Cvss Version
- 4.0
- State
- PUBLISHED
- Remediation Level
- null
Threat ID: 6a15d22e891d628fdc600885
Added to database: 05/26/2026, 17:02:38 UTC
Last enriched: 06/02/2026, 21:19:59 UTC
Last updated: 07/31/2026, 19:22:59 UTC
Views: 72
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