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CVE-2026-49440

7.4 · HIGH

Deno is a JavaScript, TypeScript, and WebAssembly runtime.

Published Jun 23, 2026CWE-325EPSS 0.24%

Overview

CVE-2026-49440 is a high-severity vulnerability. It was published on June 23, 2026 and has a CVSS 3.1 base score of 7.4 (HIGH).

This vulnerability has a CVSS 3.1 base score of 7.4, rated HIGH. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

Technical description

Deno is a JavaScript, TypeScript, and WebAssembly runtime. Prior to 2.8.1, node:crypto.checkPrime(candidate[, options][, callback]) and crypto.checkPrimeSync(candidate[, options]) ran no Miller-Rabin rounds at all when the caller left options.checks at its default of 0. In that mode, the only test applied to the candidate was trial division by the primes up to 17,863. Any composite whose smallest prime factor exceeds that bound — for example the product of two primes just above it, such as 17,881 × 17,891 — was reported as true ("probably prime"). The same divergence affected the lower-level op_node_check_prime / op_node_check_prime_bytes paths that the polyfill calls into. This vulnerability is fixed in 2.8.1.

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References

GitHubgithub.com/denoland/deno/pull/34391GitHubgithub.com/denoland/deno/security/advisories/GHSA-9xg4-qhm4-g43w

How CyberStrike helps

Frequently asked questions

What is CVE-2026-49440?

CVE-2026-49440 is a high-severity vulnerability. It was published on June 23, 2026 and has a CVSS 3.1 base score of 7.4 (HIGH).

How severe is CVE-2026-49440?

This vulnerability has a CVSS 3.1 base score of 7.4, rated HIGH. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

How do I fix or remediate CVE-2026-49440?

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-2026-49440?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2026-49440 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

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