enspirit
Elo: Sandbox escape to arbitrary Node.js / browser code execution via unfiltered `.constructor` member access in Elo JavaScript emitter
Not on CISA's list of exploited flaws, and not in the news we track.
CVE-2026-44267Critical9.8
Black Shard's team can check your exposure to CVE-2026-44267 and take the fix off your plate.
Elo is a purely functional expression language for no-code tools. Prior to 1.0.1, plain Elo strings supplied to defaultFormats.elo.parse(), bin/elo, or elo-lang.org/try can use.constructor.constructor to reach JavaScript Function because the member_access handler in src/transform.ts does not reject meta-properties, src/compilers/javascript.ts emits the surviving property directly, and src/parser.ts accepts constructor as an ordinary identifier. The resulting generated JavaScript executes attacker-selected code in the host runtime. This permits browser script execution and session compromise on the auto-running playground and arbitrary Node.js code execution on library, CI, or DevOps hosts. This plain-string path is distinct from the programmatic AST-object injection issue. This issue is fixed in version 1.0.1.
Black Shard's team can check your exposure, take a fix off your plate or step in on a live incident.
Chance of exploitation in the next 30 days
0.83%
EPSS score from FIRST
Updated 13 Nov 2026, 12:04 UTC, 31 of 36 sources answering.
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