CVE-2026-43981 HIGH

CVE-2026-43981: Algernon: Race Condition in handle() shared LState

Vendor Xyproto
Product algernon
Weakness CWE-362
Published May 26, 2026
Last update May 27, 2026
View on NVD All CVEs

CVSS base score

8.2/10
Attack vector Network
Attack complexity High
Privileges required None
User interaction None
Confidentiality —
Integrity —

CVSS vector

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

What the vulnerability does

01Description

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.

Key dates

02Disclosure timeline

May 26, 2026 CVE published
May 27, 2026 Record updated