Hono has a non-breaking space prefix bypass in cookie name handling in getCookie()

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Summary

CVECVE-2026-39410
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-04-08 15:16:15 UTC
Updated2026-04-21 18:26:00 UTC
DescriptionHono is a Web application framework that provides support for any JavaScript runtime. Prior to 4.12.12, a discrepancy between browser cookie parsing and parse() handling allows cookie prefix protections to be bypassed. Cookie names that are treated as distinct by the browser may be normalized to the same key by parse(), allowing attacker-controlled cookies to override legitimate ones. This vulnerability is fixed in 4.12.12.

Risk And Classification

Primary CVSS: v3.1 4.8 MEDIUM from [email protected]

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

EPSS: 0.000280000 probability, percentile 0.078850000 (date 2026-04-22)

Problem Types: CWE-20 | NVD-CWE-noinfo | CWE-20 CWE-20: Improper Input Validation

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary4.8MEDIUMCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N
3.1CNADECLARED4.8MEDIUMCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N

CVSS v3.1 Breakdown

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

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

NVD Known Affected Configurations (CPE 2.3)

TypeVendorProductVersionUpdateEditionLanguage
Application Hono Hono All All All All

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Honojs Hono affected < 4.12.12 Not specified

References

ReferenceSourceLinkTags
github.com/honojs/hono/commit/cc067c85592415cb1880ad3c61ed923472452ec0 [email protected] github.com Third Party Advisory
github.com/honojs/hono/releases/tag/v4.12.12 [email protected] github.com Release Notes
github.com/honojs/hono/security/advisories/GHSA-r5rp-j6wh-rvv4 [email protected] github.com Vendor Advisory
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