Hono - Missing Cookie Name Validation in setCookie()

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Hono before 4.12.12 does not validate cookie names on the write path in the setCookie(), serialize(), and serializeSigned() functions, allowing invalid characters such as control characters (e.g. \r or \n) when an application passes a user-controlled cookie name. This can produce malformed Set-Cookie header values. In modern runtimes such as Node.js and Cloudflare Workers, such invalid header values are rejected and cause a runtime error before the response is sent, so header injection or response splitting could not be reproduced; the issue primarily affects correctness and robustness, resulting in runtime errors (availability) rather than confirmed header injection.

Source published

23 Jun 2026 12:13:06 UTC

Source modified

24 Jun 2026 11:17:03 UTC

Saved here

23 Oct 2026 15:48:27 UTC

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CVSS 4.0 · 6.9 CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N

CVSS 3.1 · 5.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

Hono before 4.12.12 does not validate cookie names on the write path in the setCookie(), serialize(), and serializeSigned() functions, allowing invalid characters such as control characters (e.g. \r or \n) when an application passes a user-controlled cookie name. This can produce malformed Set-Cookie header values. In modern runtimes such as Node.js and Cloudflare Workers, such invalid header values are rejected and cause a runtime error before the response is sent, so header injection or response splitting could not be reproduced; the issue primarily affects correctness and robustness, resulting in runtime errors (availability) rather than confirmed header injection.

Source published

Jun 23, 2026, 12:13:06 PM (timezone not stated)

Source modified

Jun 24, 2026, 11:17:03 AM (timezone not stated)

Saved here

11 Nov 2026 14:07:11 UTC

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ENISA EUVD · source terms and attribution apply

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EUVD CVSS 4.0 · 6.9 CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N

Hono before 4.12.12 does not validate cookie names on the write path in the setCookie(), serialize(), and serializeSigned() functions, allowing invalid characters such as control characters (e.g. \r or \n) when an application passes a user-controlled cookie name. This can produce malformed Set-Cookie header values. In modern runtimes such as Node.js and Cloudflare Workers, such invalid header values are rejected and cause a runtime error before the response is sent, so header injection or response splitting could not be reproduced; the issue primarily affects correctness and robustness, resulting in runtime errors (availability) rather than confirmed header injection.

Source published

23 Jun 2026 13:16:46 UTC

Source modified

24 Jun 2026 13:16:37 UTC

Saved here

25 Oct 2026 14:19:10 UTC

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CVSS 4.0 · [email protected] · Secondary · 6.9 CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

CVSS 3.1 · [email protected] · Secondary · 5.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

## Summary Cookie names are not validated on the write path when using `setCookie()`, `serialize()`, or `serializeSigned()` to generate Set-Cookie headers. While certain cookie attributes such as domain and path are validated, the cookie name itself may contain invalid characters. This results in inconsistent handling of cookie names between parsing (read path) and serialization (write path). ## Details When applications use `setCookie()`, `serialize()`, or `serializeSigned()` with a user-controlled cookie name, invalid values (e.g., containing control characters such as `\r` or `\n`) can be used to construct malformed `Set-Cookie` header values. For example: ``` Set-Cookie: legit X-Injected: evil=value ``` However, in modern runtimes such as Node.js and Cloudflare Workers, such invalid header values are rejected and result in a runtime error before the response is sent. As a result, the reported header injection / response splitting behavior could not be reproduced in these environments. ## Impact Applications that pass untrusted input as the cookie name to `setCookie()`, `serialize()`, or `serializeSigned()` may encounter runtime errors due to invalid header values. In tested environments, malformed `Set-Cookie` headers are rejected before being sent, and the reported header injection behavior could not be reproduced. This issue primarily affects correctness and robustness rather than introducing a confirmed exploitable vulnerability.

Source published

8 Apr 2026 00:17:02 UTC

Source modified

24 Sep 2026 18:45:10 UTC

Saved here

24 Oct 2026 13:17:17 UTC

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GitHub Advisory Database · CC-BY-4.0

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CVSS_V3 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

Publisher rating · MODERATE

### Duplicate Advisory This advisory has been withdrawn because it is a duplicate of GHSA-26pp-8wgv-hjvm. This link is maintained to preserve external references. ### Original Description Hono before 4.12.12 does not validate cookie names on the write path in the setCookie(), serialize(), and serializeSigned() functions, allowing invalid characters such as control characters (e.g. \r or \n) when an application passes a user-controlled cookie name. This can produce malformed Set-Cookie header values. In modern runtimes such as Node.js and Cloudflare Workers, such invalid header values are rejected and cause a runtime error before the response is sent, so header injection or response splitting could not be reproduced; the issue primarily affects correctness and robustness, resulting in runtime errors (availability) rather than confirmed header injection.

Source published

23 Jun 2026 15:32:37 UTC

Source modified

24 Sep 2026 18:45:10 UTC

Saved here

24 Oct 2026 13:17:17 UTC

Source terms

GitHub Advisory Database · CC-BY-4.0

Original source record · Cite this exact observation · Complete original publisher JSON

Source: osv · GitHub Advisory Database · CC-BY-4.0. The publisher's wording is preserved. ChangeIntel groups the information and labels changes. The JSON record includes additional source fields.

CVSS_V3 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

CVSS_V4 · CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Publisher rating · MODERATE