CVE-2025-48934
Deno.env.toObject() ignores the variables listed in --deny-env and returns all environment variables
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
Blast Radius
deno🦀deno🦀deno_runtimeReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects crates.io packages — download data is not available via public APIs for these ecosystems.
Description
Deno is a JavaScript, TypeScript, and WebAssembly runtime. Prior to versions 2.1.13 and 2.2.13, the Deno.env.toObject method ignores any variables listed in the --deny-env option of the deno run command. When looking at the documentation of the --deny-env option this might lead to a false impression that variables listed in the option are impossible to read. Software relying on the combination of both flags to allow access to most environment variables except a few sensitive ones will be vulnerable to malicious code trying to steal secrets using the Deno.env.toObject() method. Versions 2.1.13 and 2.2.13 contains a patch.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🦀crates.io | deno | all versions | 2.1.13 |
| 🦀crates.io | deno | ≥ 2.2.0&&< 2.2.13 | 2.2.13 |
| 🦀crates.io | deno_runtime | all versions | 0.212.0 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for deno. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update deno to 2.1.13 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2025-48934 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether CVE-2025-48934 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to CVE-2025-48934. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2025-48934 in your dependencies?
O3 detects CVE-2025-48934 across crates.io dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.