denoland deno up to 2.8.0 missing cryptographic step

Summaryinfo

A vulnerability was found in denoland deno up to 2.8.0. It has been rated as problematic. Affected is an unknown function. This manipulation causes missing cryptographic step. The identification of this vulnerability is CVE-2026-49440. It is possible to initiate the attack remotely. There is no exploit available. Upgrading the affected component is advised.

Detailsinfo

A vulnerability has been found in denoland deno up to 2.8.0 and classified as problematic. Affected by this vulnerability is an unknown function. The manipulation with an unknown input leads to a missing cryptographic step vulnerability. The CWE definition for the vulnerability is CWE-325. The product does not implement a required step in a cryptographic algorithm, resulting in weaker encryption than advertised by the algorithm. As an impact it is known to affect confidentiality, integrity, and availability. The summary by CVE is:

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.

The advisory is shared at github.com. This vulnerability is known as CVE-2026-49440 since 05/30/2026. The exploitation appears to be difficult. The attack can be launched remotely. The exploitation doesn't need any form of authentication. Neither technical details nor an exploit are publicly available. MITRE ATT&CK project uses the attack technique T1600 for this issue.

Upgrading to version 2.8.1 eliminates this vulnerability. Applying a patch is able to eliminate this problem. The bugfix is ready for download at github.com. The best possible mitigation is suggested to be upgrading to the latest version.

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Productinfo

Vendor

• denoland

Name

• deno

Version

• 2.0
• 2.1
• 2.2
• 2.3
• 2.4
• 2.5
• 2.6
• 2.7
• 2.8.0

Website

• Product: https://github.com/denoland/deno/

CPE 2.3info

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Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

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