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

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-126359
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-11-13 00:20:11 UTC
Updated2026-11-13 00:20:11 UTC
DescriptionHono 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.

Risk And Classification

Primary CVSS: v3.1 3.4 LOW from [email protected]

CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:L/I:N/A:N

Problem Types: CWE-79 | CWE-79 CWE-79: Improper Neutralization of Input During Web Page Generation

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary3.4LOWCVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:L/I:N/A:N
3.1CNADECLARED3.4LOWCVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:L/I:N/A:N

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
High
Privileges Required
None
User Interaction
Required
Scope
Changed
Confidentiality
Low
Integrity
None
Availability
None

CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:L/I:N/A:N

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Honojs Hono affected >= 3.12.0, < 4.13.16 Not specified

References

ReferenceSourceLinkTags
github.com/honojs/hono/releases/tag/v4.13.16 [email protected] github.com
github.com/honojs/hono/security/advisories/GHSA-3gg2-335m-rxc6 [email protected] github.com
github.com/honojs/hono/commit/15bbd96ad1b62a0b189db4fd8dc7bf8ef280c513 [email protected] github.com
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