CVE-2026-49440Public exploitNetwork attack vectorHinoki check available

Cryptographic validation bypass via zero-round primality test

Published Jun 23, 2026 · Updated Jun 23, 2026

Cryptographic validation flaw in Deno before 2.8.1 allows remote attackers to pass crafted composite numbers as prime. The node:crypto checkPrime and checkPrimeSync paths forward the default checks value of zero to is_probably_prime, skipping every Miller-Rabin round after limited trial division. Exposure requires an application to validate attacker-controlled numbers with default options and trust the result in a security-sensitive protocol, whose guarantees then depend on the crafted composite.

CVSS severity7.4
High
EPSS probability0.24%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkAvailable
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Summary

What happened

Cryptographic validation flaw in Deno before 2.8.1 allows remote attackers to pass crafted composite numbers as prime. The node:crypto checkPrime and checkPrimeSync paths forward the default checks value of zero to is_probably_prime, skipping every Miller-Rabin round after limited trial division. Exposure requires an application to validate attacker-controlled numbers with default options and trust the result in a security-sensitive protocol, whose guarantees then depend on the crafted composite.

The record

CVE
CVE-2026-49440
Published
Jun 23, 2026
Updated
Jun 23, 2026
Vendor
Deno Land Inc.
Product
Deno
Classifications
CWE-325
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jun 23, 2026CVE publishedPublication date reported by the CVE source.
  2. Jun 23, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 2.8.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Deno Land Inc. · Denoversion=< 2.8.1

Published CVSS scores

7.4GitHub, Inc.CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-325Missing Cryptographic Step

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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