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Fencer Intel
low 3.4

CVE-2026-126359 json

Hono: `css` helper does not escape a closing tag split between the template and an interpolated value, allowing HTML injection

published 14d ago modified 2d ago also EUVD-2026-124740 , GHSA-3gg2-335m-rxc6

cvss
3.4
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.3%
EPSS 0.3% chance of exploitation in 30 days, percentile 18%
public exploits
0
none known

Summary

Hono is a Web application framework that provides support for any JavaScript runtime. From 3.12.0 until 4.13.16, the css helper in hono/css escapes interpolated string values separately and therefore fails to neutralize a closing style tag when < ends the template text or a preceding value and / begins the next attacker-controlled value. During server-side rendering, the combined output can close the <Style /> element early and cause the remainder of the interpolated value to be interpreted as HTML. Applications that place an untrusted string immediately after < in a css template, including adjacent untrusted interpolations, can expose viewers to attacker-controlled HTML or script and information accessible to that page. Other uses of the css helper are not affected. This issue is fixed in version 4.13.16.

Patch / fix

  • npm hono 4.13.16

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Exploit prediction

0.26% chance of exploitation in the next 30 days, higher than 18% of all scored CVEs (FIRST EPSS, 2026-11-14).

CVSS scores

assigned by version score vector
CNA 3.1 3.4 CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:L/I:N/A:N
GitHub 3.1 3.4 CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:L/I:N/A:N

Affected packages

ecosystem package affected fixed in
npm hono
>=3.12.0, <4.13.16
4.13.16

Affected products

  • honojs hono

Classification

Weakness
  • CWE-79 Improper Neutralization of Input During Web Page Generation

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

The maintainers of honojs/hono published their own advisory on GitHub. Reviewed sources take precedence over it.