CVE-2026-43981

HIGH

Algernon: Race Condition in handle() shared LState

Title source: cna
STIX 2.1

Description

Algernon is a small self-contained pure-Go web server. Prior to 1.17.6, in engine/luahandler.go, the sync.RWMutex protecting LoadCommonFunctions is released before L.Push() and L.PCall() execute. Since gopher-lua's LState is explicitly not goroutine-safe, concurrent requests race on the shared state causing Lua VM corruption. The Go race detector confirms this immediately under modest concurrency (ab -n 1000 -c 100). This vulnerability is fixed in 1.17.6.

References (2)

Core 2
Core References
X_Refsource_Misc x_refsource_misc
https://github.com/xyproto/algernon/issues/172

Scores

CVSS v4 8.2
EPSS 0.0018
EPSS Percentile 7.9%
CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

CISA SSVC

Vulnrichment
Exploitation none
Automatable no
Technical Impact total

Details

CWE
CWE-362
Status published
Products (1)
xyproto/algernon < 1.17.6
Published May 26, 2026
Tracked Since May 26, 2026