CVE-2026-29086: Hono Hono Vulnerable To Cookie Attribute Vulnerability

MODERATE
Advisory Identifier: GHSA-5pq2-9x2x-5p6w
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CVSS 5.4
CWE-113 CWE-1113
Published
Advisory Summary

CVE-2026-29086 is a MODERATE (CVSS 5.4) hono vulnerable to cookie attribute vulnerability (CWE-113: Improper Neutralization of CRLF Sequences in HTTP Headers ('HTTP Request/Response Splitting')) affecting Hono libraries in the npm ecosystem. The issue involves hono vulnerable to cookie attribute injection via unsanitized domain and path in setcookie(). Remediation is available by upgrading affected packages to version 4.12.4.

CVE-2026-29086 at a Glance

CVE Identifier CVE-2026-29086
GHSA Identifier GHSA-5pq2-9x2x-5p6w
Severity MODERATE
CVSS v3.1 Base Score 5.4
CWE Classification CWE-113: Improper Neutralization of CRLF Sequences in HTTP Headers ('HTTP Request/Response Splitting')
Affected Product Hono
Package Ecosystem npm
Published Date
Last Updated

Security Impact

CVSS: 5.4

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N).

Attack Vector Network (AV:N)
Attack Complexity Low (AC:L)
Privileges Required None (PR:N)
User Interaction Required (UI:R)
Scope Unchanged (S:U)
Confidentiality Low (C:L)
Integrity Low (I:L)
Availability None (A:N)

How to Fix CVE-2026-29086

To remediate this vulnerability, upgrade all affected Hono dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

hono fixed: 4.12.4 
npm install hono@4.12.4
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

npm ls hono

How to Check if You Are Affected

To determine whether your Node.js application is affected by CVE-2026-29086, inspect your project dependencies using npm:

npm ls hono

Analyze the terminal output to locate any version of Hono in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 4.12.4), your application is affected.

Note: The npm ls hono command inspects dependencies declared in your package.json and lockfile; it does not perform automated runtime dynamic scanning.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-113: Improper Neutralization of CRLF Sequences in HTTP Headers ('HTTP Request/Response Splitting'), where the product receives data from an http agent/component (e.g., web server, proxy, browser, etc.), but it does not neutralize or incorrectly neutralizes cr and lf characters before the data is included in outgoing http headers. In Hono, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

## Summary 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. ## Details `setCookie()` builds the `Set-Cookie` header by concatenating option values. While the cookie value itself is URL-encoded, the `domain` and `path` options were previously interpolated without rejecting unsafe characters. Including `;`, `\r`, or `\n` in these fields could result in unintended additional attributes (such as `SameSite`, `Secure`, `Domain`, or `Path`) being appended to the cookie header. Modern runtimes prevent full header injection via CRLF, so this issue is limited to attribute-level manipulation within a single `Set-Cookie` header. The issue has been fixed by rejecting these characters in the `domain` and `path` options. ## Impact An attacker may be able to manipulate cookie attributes if an application passes user-controlled input directly into the `domain` or `path` options of `setCookie()`. This could affect cookie scoping or security attributes depending on browser behavior. Exploitation requires application-level misuse of cookie options.

CVE-2026-29086 Affected Hono Versions

1 component(s)
Fixed Versions:
4.12.4
Product / Package Ecosystem Affected Versions Fixed Version
hono
npm/hono
npm
< 4.12.4
4.12.4

References

GitHub Advisory / Wiki ADVISORY
https://github.com/honojs/hono/security/advisories/GHSA-5pq2-9x2x-5p6w
NVD — CVE-2026-29086 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-29086
Security Fix Commit FIX COMMIT
https://github.com/honojs/hono/commit/44ae0c8cc4d5ab2bed529127a4ac72e1483ad073
Hono Source Repository REPOSITORY
https://github.com/honojs/hono

Frequently Asked Questions

What is CVE-2026-29086?
CVE-2026-29086 is a security vulnerability in Hono involving Hono Vulnerable to Cookie Attribute Injection via Unsanitized domain and path in setCookie() under CWE-113: Improper Neutralization of CRLF Sequences in HTTP Headers ('HTTP Request/Response Splitting').
Which Hono versions are affected?
Affected versions include releases prior to 4.12.4 across affected packages: hono.
What version fixes CVE-2026-29086?
Upgrading to 4.12.4 (or the latest patched release for your respective branch) resolves the vulnerability.
Is hono affected?
Yes, hono is affected in releases prior to 4.12.4. Upgrade your dependency to 4.12.4 or later.
What is the CVSS score of CVE-2026-29086?
CVE-2026-29086 has a CVSS v3.1 base score of 5.4 (MODERATE) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N.
What CWE is associated with CVE-2026-29086?
CVE-2026-29086 is classified under CWE-113: Improper Neutralization of CRLF Sequences in HTTP Headers ('HTTP Request/Response Splitting') (The product receives data from an HTTP agent/component (e.g., web server, proxy, browser, etc.), but it does not neutralize or incorrectly neutralizes CR and LF characters before the data is included in outgoing HTTP headers.).
How can I check npm dependencies for CVE-2026-29086?
Run the dependency tree command: 'npm ls hono'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-5pq2-9x2x-5p6w",
  "modified" : "2026-03-05T15:26:43Z",
  "published" : "2026-03-04T19:49:14Z",
  "aliases" : [ "CVE-2026-29086" ],
  "summary" : "Hono Vulnerable to Cookie Attribute Injection via Unsanitized domain and path in setCookie()",
  "details" : "## Summary\n\nThe `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.\n\nBecause cookie attributes are delimited by semicolons, this could allow injection of additional cookie attributes if untrusted input was passed into these fields.\n\n## Details\n\n`setCookie()` builds the `Set-Cookie` header by concatenating option values. While the cookie value itself is URL-encoded, the `domain` and `path` options were previously interpolated without rejecting unsafe characters.\n\nIncluding `;`, `\\r`, or `\\n` in these fields could result in unintended additional attributes (such as `SameSite`, `Secure`, `Domain`, or `Path`) being appended to the cookie header.\n\nModern runtimes prevent full header injection via CRLF, so this issue is limited to attribute-level manipulation within a single `Set-Cookie` header.\n\nThe issue has been fixed by rejecting these characters in the `domain` and `path` options.\n\n## Impact\n\nAn attacker may be able to manipulate cookie attributes if an application passes user-controlled input directly into the `domain` or `path` options of `setCookie()`.\n\nThis could affect cookie scoping or security attributes depending on browser behavior. Exploitation requires application-level misuse of cookie options.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "npm",
      "name" : "hono"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "4.12.4"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/honojs/hono/security/advisories/GHSA-5pq2-9x2x-5p6w"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-29086"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/honojs/hono/commit/44ae0c8cc4d5ab2bed529127a4ac72e1483ad073"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/honojs/hono"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-1113", "CWE-113" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-03-04T19:49:14Z",
    "nvd_published_at" : "2026-03-04T23:16:10Z"
  }
}