5.4

CVE-2026-29086: hono Inappropriate Comment Style

CVSS: 5.4v3.1MediumAnalyzed
AliasesGHSA-5pq2-9x2x-5p6wCGA-2rmc-h3w4-w8hhCGA-3833-jmx3-vgp5
Published 04-03-2026Last modified 05-03-2026
Open JSON

Vulnerability summary

CVE-2026-29086 is a medium (CVSS 5.4) Inappropriate Comment Style vulnerability in hono. EPSS estimates a 0.28% chance of exploitation in the next 30 days, higher than 19.2% of scored vulnerabilities.

Overall risk
22/100
0100
Low · default modelHow is this calculated?
CVSS score
5.4/10
010
Medium · v3.1 (CVE.org)
EPSS score
0.28%
0%100%
Low · +0.06 pp in 30 days
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded

Advisory lineage

Upstream 0 · Downstream 0 · Related 1
CGA-R6JM-C92F-47GG

Timeline

  1. 04-03-2026
    PublishedVulnerability first disclosed.
  2. 05-03-2026
    Last modifiedVulnerability information updated.

Description

Hono is a Web application framework that provides support for any JavaScript runtime. Prior to version 4.12.4, the setCookie() utility did not validate semicolons (;), carriage returns (\r), or newline characters (\n) in the domain and path options when constructing the Set-Cookie header. Because cookie attributes are delimited by semicolons, this could allow injection of additional cookie attributes if untrusted input was passed into these fields. This issue has been patched in version 4.12.4.

CVSS metrics

4 scores · 4 sources · 1 version

EPSS trend

Probability

0.28%

Chance of exploitation in the next 30 days

Percentile

19%

Versus all other CVEs

30-day change

+0.06 pp

From 0.22% on 21-09-2026

21-09-202621-10-2026
EPSS score
0.28%

Known exploited

Compare KEV catalogs

Not in any of the 3 tracked catalogs.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Chainguard13 products
  • honoAll versions (No fix recorded)
  • hono-adapter-mqttAll versions (No fix recorded)
  • hono-cliAll versions (No fix recorded)
  • hono-compatAll versions (No fix recorded)
  • hono-service-authAll versions (No fix recorded)
Hono1 product
Honojs1 product
Npm1 product
  • hono< 4.12.4

4 vendors · 16 products

References

5 links