CVE-2026-69207Network attack vector

Unauthenticated service interruption via quadratic header parsing

Published Aug 7, 2026 · Updated Aug 7, 2026

Regular expression denial of service in Hono before 4.12.34 allows remote attackers to interrupt service via crafted preflight requests. The CORS middleware splits Access-Control-Request-Headers with a whitespace-tolerant regular expression whose backtracking is quadratic on long whitespace runs. No authentication or user interaction is required, but the path is reachable only when cors() uses an unset or empty allowHeaders; repeated requests can stall concurrent processing.

CVSS severity5.3
Medium
EPSS probability0.49%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Regular expression denial of service in Hono before 4.12.34 allows remote attackers to interrupt service via crafted preflight requests. The CORS middleware splits Access-Control-Request-Headers with a whitespace-tolerant regular expression whose backtracking is quadratic on long whitespace runs. No authentication or user interaction is required, but the path is reachable only when cors() uses an unset or empty allowHeaders; repeated requests can stall concurrent processing.

The record

CVE
CVE-2026-69207
Published
Aug 7, 2026
Updated
Aug 7, 2026
Vendor
Hono
Product
Hono
Classifications
CWE-1333, CAPEC-492, T1499.003
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 7, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 7, 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=< 4.12.34

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Hono · Honoversion=< 4.12.34

Published CVSS scores

5.3GitHubCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-1333Inefficient Regular Expression Complexity
CAPEC-492Regular Expression Exponential Blowup
T1499.003Endpoint Denial of Service: Application Exhaustion Flood

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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