CVE-2026-49440: CWE-325: Missing Cryptographic Step in denoland deno
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.
AI Analysis
Technical Summary
The vulnerability in denoland's Deno runtime affects the node:crypto.checkPrime(candidate[, options][, callback]) and crypto.checkPrimeSync(candidate[, options]) functions prior to version 2.8.1. When the options.checks parameter is set to its default of 0, these functions skip the Miller-Rabin primality test rounds and only perform trial division by primes up to 17,863. This allows composite numbers whose smallest prime factor exceeds 17,863 to be falsely reported as prime. The lower-level op_node_check_prime and op_node_check_prime_bytes paths are similarly affected. This flaw is addressed in Deno 2.8.1.
Potential Impact
The vulnerability can lead to incorrect identification of composite numbers as prime, potentially undermining cryptographic operations that rely on prime number verification. This can compromise the confidentiality and integrity of cryptographic processes using these functions. The CVSS score of 7.4 reflects a high severity with network attack vector, high impact on confidentiality and integrity, and no privileges or user interaction required.
Mitigation Recommendations
A fix is available in Deno version 2.8.1. Users and administrators should upgrade to version 2.8.1 or later to resolve this vulnerability. No other mitigation steps are indicated.
CVE-2026-49440: CWE-325: Missing Cryptographic Step in denoland deno
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.
CVSS v3.1
Score 7.4high
Affected software
Run on your own infrastructure? Check whether these packages are installed with threat-finder — our free open-source scanner.
Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
The vulnerability in denoland's Deno runtime affects the node:crypto.checkPrime(candidate[, options][, callback]) and crypto.checkPrimeSync(candidate[, options]) functions prior to version 2.8.1. When the options.checks parameter is set to its default of 0, these functions skip the Miller-Rabin primality test rounds and only perform trial division by primes up to 17,863. This allows composite numbers whose smallest prime factor exceeds 17,863 to be falsely reported as prime. The lower-level op_node_check_prime and op_node_check_prime_bytes paths are similarly affected. This flaw is addressed in Deno 2.8.1.
Potential Impact
The vulnerability can lead to incorrect identification of composite numbers as prime, potentially undermining cryptographic operations that rely on prime number verification. This can compromise the confidentiality and integrity of cryptographic processes using these functions. The CVSS score of 7.4 reflects a high severity with network attack vector, high impact on confidentiality and integrity, and no privileges or user interaction required.
Mitigation Recommendations
A fix is available in Deno version 2.8.1. Users and administrators should upgrade to version 2.8.1 or later to resolve this vulnerability. No other mitigation steps are indicated.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- GitHub_M
- Date Reserved
- 2026-05-30T02:43:33.105Z
- Cvss Version
- 3.1
- State
- PUBLISHED
- Remediation Level
- null
Threat ID: 6a3ac4efeed863c81e61823a
Added to database: 06/23/2026, 17:39:59 UTC
Last enriched: 06/30/2026, 23:09:21 UTC
Last updated: 08/06/2026, 12:41:11 UTC
Views: 56
Community Reviews
0 reviewsCrowdsource mitigation strategies, share intel context, and vote on the most helpful responses. Sign in to add your voice and help keep defenders ahead.
Want to contribute mitigation steps or threat intel context? Sign in or create an account to join the community discussion.
Actions
Updates to AI analysis require Pro Console access. Upgrade inside Console → Billing.
Need more coverage?
Upgrade to Pro Console for AI refresh and higher limits.
For incident response and remediation, OffSeq services can help resolve threats faster.
Latest Threats
Check if your credentials are on the dark web
Instant breach scanning across billions of leaked records. Free tier available.