CVE-2026-29086 Hono: Cookie Attribute Injection via Unsanitized domain and path in setCookie()
Attackers can inject cookie attributes via unsanitized domain or path inputs in Hono's setCookie function, potentially bypassing security controls.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- Available
What is CVE-2026-29086?
CVE-2026-29086 is a medium-severity vulnerability in honojs hono, published on 4 Mar 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Official 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.
Weakness: CWE-1113
Which versions are affected by CVE-2026-29086?
2 open source packages ship an affected version, including hono. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
hono npm | All versions | 4.12.4 |
hono npm | All versions | 4.12.4 |
Products include Hono Hono.
How do I fix CVE-2026-29086?
Upgrade hono to 4.12.4 or later.
Is CVE-2026-29086 being exploited?
There is no known exploitation of CVE-2026-29086 in the wild and no public exploit code.
Other vulnerabilities in honojs hono
- CVE-2026-27700 Hono is Vulnerable to Authentication Bypass by IP Spoofing in AWS Lambda ALB conninfo
- CVE-2026-22817 JWT Algorithm Confusion via Unsafe Default (HS256) in Hono JWT Middleware Allows Token Forgery and Auth Bypass
- CVE-2026-22818 JWT algorithm confusion in Hono JWK Auth Middleware when JWK lacks "alg" (untrusted header.alg fallback)
- CVE-2025-62610 Hono Improperly Authorizes JWT Audience Validation
- CVE-2026-29045 Hono: Arbitrary file access via serveStatic vulnerability
Sources
Also known as CLEANSTART-2026-NA27145, CLEANSTART-2026-NF09700, GHSA-5pq2-9x2x-5p6w, MINI-25pr-cvw3-x27p, MINI-7rxw-5vg9-77wf, MINI-fc86-p727-ffhv and 3 more.