vulnerability / NVI-00013158 / Revision 3
Hono missing validation of cookie name on write path in setCookie()
GitHub lists this reviewed advisory for hono. Published version ranges and source prerequisites are shown below; this is not an inspection of a visitor’s application.
This report has not inspected your inventory, configuration, deployed build, reachability or evidence. A catalog listing and a severity score do not establish exposure or compromise.
01 / Meaning
Why it matters
Published affected context helps an owner decide what evidence to gather. This report has not examined your application.
5.3 medium
GitHub source severity; exploitability and local consequence require separate evidence.
As of · GitHub Advisory Database
5.3 MEDIUM (3.1)
disclosure@vulncheck.com severity; no combined Null risk score.
6.9 MEDIUM (4.0)
disclosure@vulncheck.com severity; no combined Null risk score.
0.418%
FIRST EPSS model v2026.06.15; exploitation probability over 30 days, percentile 0.36123. Missing scores are unknown.
As of · FIRST EPSS
02 / Applicability
The affected context
Affected versions, configuration prerequisites and known exclusions are public. Confirm each one against the deployed service.
hono
source listed< 4.12.12
## 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. I
03 / Response
What to do next
- investigate
Identify the exact component and deployed version, examine the linked publisher’s conditions, and retain evidence of any mitigation.
Confirm current vendor support, compatibility and deployment evidence. This report has not tested a fix in your system. FIRST EPSS
A fixed release is not deployment evidence.
Check current vendor support and compatibility. After making a change, verify the deployed build and relevant runtime conditions. Keep the evidence, owner and time. An updated lockfile alone does not prove what is running.
04 / Limits
What this report cannot establish
- Customer inventory, deployment, reachability and exploitation have not been inspected.
- NVD lastModified does not establish freshness of every associated CPE record.
05 / Provenance
Sources you can inspect
Each assertion retains its source. Mirrored records may repeat one underlying publisher; additional links are not independent corroboration.
- GHSA-26pp-8wgv-hjvm ↗
GitHub Advisory Database · vendor advisory
Observed . GitHub Advisory Database; CC-BY-4.0. Each advisory links its original attribution. Null normalizes fields.
- CVE-2026-56762 ↗
NIST National Vulnerability Database · official catalog
Observed . This product uses data from the NVD API but is not endorsed or certified by the NVD.
- CVE-2026-56762 ↗
FIRST EPSS · official catalog
Observed . FIRST EPSS; probability of exploitation in the next 30 days, not local compromise. Dataset date/model retained; FIRST services terms apply.
Public revision history
Only published revisions appear here. Routine fetches do not create a material-change event.
- Revision 3 ·
Source facts changed; compare the preserved prior revision.
- Revision 2 ·
Dated EPSS estimate updated; this is not a new disclosure or proof of exploitation.
- Revision 1 ·
First indexed by Null; source disclosure date is shown separately.