https://vulnfeed.org/Every disclosure, as it lands. Critical-only feed available.enhttps://vulnfeed.org/cve/CVE-2026-44267/https://vulnfeed.org/cve/CVE-2026-44267/Tue, 03 Nov 2026 17:53:42 +0000### Summary An unauthenticated attacker who controls a string passed to any Elo JavaScript-emission path — `defaultFormats.elo.parse()`, the `bin/elo` CLI, or the live browser playground at `elo-lang.org/try` — can execute arbitrary code in the host JavaScript runtime. A payload built from the `.constructor.constructor` chain compiles, without modification, to a live `Function` invocation in the emitted JavaScript, escaping any sandbox assumption around "Elo is a safe data/DSL language." ### Vulnerable sink and root cause Three interacting sites in `src/` produce the bug at commit `749af7b`: 1. **`src/transform.ts:144–158`** — the `member_access` handler allows access on types `any`, `object`, or `array` without filtering the property name. This is the only place an integrator could have plugged a denylist. 2. **`src/compilers/javascript.ts:210`** — the JS emitter writes `${objectExpr}.${ir.property}` verbatim into the output, so any property name that survives the transform step flows unescaped into emitted JavaScript. 3. **`src/parser.ts:163–170, 748–750`** — the parser accepts `constructor` (and other JS meta-property names) as an ordinary identifier, so `.constructor` clears type-checking without triggering any warning. Combined, the Elo expression `({}).constructor.constructor('…')()` compiles to a live `Function('…')()` call in the emitted JS, executing in the realm of whichever sink runs the compiled code. ### Attack surfaces All three surfaces share the same root cause (no denylist in `transform.ts`) and are addressed by the same one-file patch: | # | Entry point | Threat model | |---|---|---| | 1 | Browser playground — `https://elo-lang.org/try/?code=…&run=1` | **0-click XSS / account takeover** against elo-lang.org. `?run=1` triggers `setTimeout(() => this.run(), 100)` in `playground_controller.ts:531`; the server issues a 301 that preserves `?code=`. Any shared URL that contains a payload compromises the visitor's session on elo-lang.org. | | 2 | `bin/el…https://vulnfeed.org/cve/CVE-2026-44266/https://vulnfeed.org/cve/CVE-2026-44266/Tue, 03 Nov 2026 17:51:30 +0000### Summary Elo's Ruby backend emits attacker-controlled text into Ruby double-quoted strings without escaping the `#` character. Because `#` begins Ruby's interpolation sequences — `#{expr}`, `#@ivar`, `#@@cvar`, `#$gvar` — and any expression wrapped in `#{...}` may use backticks for shell execution, an Elo program that contains a crafted string literal or a labelled subtype constraint compiles to Ruby that evaluates attacker-chosen Ruby, and through backticks runs attacker-chosen shell commands, at runtime. The same Elo source compiled to JavaScript, Python, or SQL is benign, so the bug also breaks the cross-target portability guarantee the rest of the compiler honours. ### Vulnerable sinks Two sinks exist in `src/compilers/ruby.ts` at commit `749af7b`: 1. **String-literal emitter — lines 180–184.** The emitter escapes backslash, double quote, and control characters, but not `#`. Any `#{...}` sequence in an Elo string literal flows straight into the emitted Ruby source. 2. **Labelled subtype-constraint branch — lines 405–412.** The error message passed to `p_fail(p, "...")` is wrapped in a Ruby double-quoted string with no escape pass at all. Because the parser at `src/parser.ts:1339–1348` accepts single-quoted Elo strings as constraint labels, a label such as `'#{` `` `id` `` `}'` flows unchanged into the emitted Ruby. ### Attack surfaces All three surfaces share the same root cause (the missing `#` escape in the Ruby double-quoted-string emission path) and are addressed by the same patch: | # | Entry point | Threat model | |---|---|---| | 1 | `/try` playground on elo-lang.org (Ruby target) | 0-click server-side RCE against elo-lang.org infrastructure from a shared PoC URL | | 2 | `bin/eloc -t ruby -x` on a CI or DevOps host | RCE on any host that passes Elo strings through the CLI | | 3 | Library API — `defaultFormats.elo.parse()` with a Ruby emission step | Ruby RCE for any downstream integrator using Elo as a rule engine, configuration DSL, or form builder DS…https://vulnfeed.org/cve/CVE-2026-44265/https://vulnfeed.org/cve/CVE-2026-44265/Tue, 03 Nov 2026 17:47:03 +0000Elo is a purely functional expression language for no-code tools. Prior to 1.0.1, Elo's programmatic AST API accepts arbitrary values from JSON-deserialized input, plugin output, or other untyped sources and interpolates them into generated JavaScript, Ruby, Python, or SQL without runtime syntax validation. The affected fields are int_literal / float_literal .value, variable.name, member_access.property, object_literal keys, datapath segments, lambda.params[].name, and the SQL let binding name. Crafted values become executable expressions or identifiers, allowing arbitrary code execution in JavaScript, Ruby, and Python targets and SQL injection in the SQL target. This programmatic AST-object path is distinct from the plain-string constructor-chain sandbox escape. This issue is fixed in version 1.0.1.