CVE-2026-49440
HighCVSS 7.4Exploitation Probability (EPSS)
Low risk4th percentile — higher than 4% of all known CVEs
Summary
In Deno prior to version 2.8.1, the `node:crypto.checkPrime` and `crypto.checkPrimeSync` functions performed no Miller-Rabin rounds when the `options.checks` parameter was left at its default value of 0. In this mode, the only test applied was trial division by primes up to 17,863, causing composite numbers whose smallest prime factor exceeds that bound to be incorrectly reported as probably prime.
Risk Assessment
Organizations may rely on false positive primality test results, which in a cryptographic context can lead to the use of weak or inappropriate prime numbers, increasing the risk of compromised encryption and digital signatures.
Recommendation
Immediately update Deno to version 2.8.1 or later, which contains the fix for this vulnerability. In the meantime, it is recommended to explicitly set the `options.checks` parameter to a value greater than 0.
Original NVD description (English source)
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.