CVE-2026-71848Network attack vector

Request-processing denial of service via quadratic language truncation

Published Aug 7, 2026 · Updated Aug 7, 2026

Algorithmic complexity denial of service in Hono 4.12.0 through 4.12.33 allows remote attackers to block request processing. normalizeLanguage() rebuilds every possible hyphen-delimited prefix with slice().join(), making work grow quadratically with subtag count. Default query, cookie, and header detectors expose this synchronous CPU load to unauthenticated requests; runtime and proxy limits bound each request.

CVSS severity5.3
Medium
EPSS probability0.29%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Algorithmic complexity denial of service in Hono 4.12.0 through 4.12.33 allows remote attackers to block request processing. normalizeLanguage() rebuilds every possible hyphen-delimited prefix with slice().join(), making work grow quadratically with subtag count. Default query, cookie, and header detectors expose this synchronous CPU load to unauthenticated requests; runtime and proxy limits bound each request.

The record

CVE
CVE-2026-71848
Published
Aug 7, 2026
Updated
Aug 7, 2026
Vendor
Hono
Product
Hono
Classifications
CWE-407, T1499.004
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=>= 4.12.0, < 4.12.34

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Hono · Honoversion=>= 4.12.0, < 4.12.34

Published CVSS scores

5.3GitHub, Inc.CVSS: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-407Inefficient Algorithmic Complexity
T1499.004Application or System Exploitation

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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