CVE-2026-43981CWE-362

Algernon: Race Condition in handle() shared LState

High · published May 26, 2026

CVSS v4.0
8.2
EPSS
0%
Percentile
19.6
In the wild
Unconfirmed
What it is

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.

The record
Technical detail
CVSS v4.0
8.2 · HIGH
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
EPSS
0.00282 · 19.6th percentile
Weakness
CWE-362 · Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')
Published
2026-05-26T16:31Z
EPSS history
Timeline
  • 26 MAY 16:31Z
    Algernon: Race Condition in handle() shared LState
    cvelistv5