CVE-2026-43981

8.2 highEPSS 0.2%

High (8.2). EPSS 0.2% chance of exploitation in the next 30 days.

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.

Severity

CVSS 4.0

8.2 high

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: 0.2% chance of exploitation in the next 30 days; higher than 7% of CVEs (scores of 2026-10-31)
CWE: CWE-362
Published: 2026-05-26
Modified: 2026-07-24
Record from: the NVD, synced 2026-10-19

References

https://github.com/xyproto/algernon/issues/172
https://github.com/xyproto/algernon/security/advisories/GHSA-rr2f-4wrm-h6rg

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