# CVE-2026-56761: hono - HTML Injection via Improper JSX Attribute Name Handling in SSR

> Attackers can inject arbitrary HTML or scripts via malformed JSX attribute names in Hono's server-side rendering, potentially leading to XSS.

- **Severity:** Medium 5.3 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N`)
- **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:** Yes
- **Published:** 24 Jun 2026
- **Updated:** 24 Jun 2026
- **Also known as:** CLEANSTART-2026-YG16880, ECHO-985a-be76-78fe, GHSA-458j-xx4x-4375, MINI-223w-382m-6v5v, MINI-22hj-9r93-47v2, MINI-6gw4-h5vm-9h7r, MINI-6vxq-pmcp-gq6p, MINI-gggg-jr85-gwmp, MINI-p74h-qmjm-83qf, MINI-w39v-8r74-4crh, ROOT-APP-NPM-CVE-2026-56761

## What is CVE-2026-56761?

CVE-2026-56761 is a medium-severity cross-site scripting vulnerability in hono, published on 24 Jun 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 before 4.12.14 contains an html injection vulnerability in jsx server-side rendering that allows attackers to inject unintended html by using malformed attribute names. Attackers can craft specially crafted attribute keys containing characters like quotes or angle brackets to break html tag boundaries and inject arbitrary attributes or elements.

Weakness: CWE-79 (Improper Neutralization of Input During Web Page Generation)

## Which versions are affected by CVE-2026-56761?

2 open source packages ship an affected version, including hono. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `hono` | npm | All versions | 4.12.14 |
| `hono` | npm | All versions | 4.12.14 |

Products: Hono Hono.

## How do I fix CVE-2026-56761?

Upgrade hono to 4.12.14 or later.

## Is CVE-2026-56761 being exploited?

There is no known exploitation of CVE-2026-56761 in the wild and no public exploit code.

## Other vulnerabilities in hono

- [CVE-2026-27700](https://insights.sbomify.com/CVE-2026-27700/): Hono is Vulnerable to Authentication Bypass by IP Spoofing in AWS Lambda ALB conninfo (high 8.2)
- [CVE-2026-22817](https://insights.sbomify.com/CVE-2026-22817/): JWT Algorithm Confusion via Unsafe Default (HS256) in Hono JWT Middleware Allows Token Forgery and Auth Bypass (high 8.2)
- [CVE-2026-22818](https://insights.sbomify.com/CVE-2026-22818/): JWT algorithm confusion in Hono JWK Auth Middleware when JWK lacks "alg" (untrusted header.alg fallback) (high 8.2)
- [CVE-2025-62610](https://insights.sbomify.com/CVE-2025-62610/): Hono Improperly Authorizes JWT Audience Validation (high 8.1)
- [CVE-2026-29045](https://insights.sbomify.com/CVE-2026-29045/): Hono: Arbitrary file access via serveStatic vulnerability (high 7.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-56761 and fix it if it is affected.

What it is: CVE-2026-56761 is a medium-severity cross-site scripting vulnerability in hono, published on 24 Jun 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2026-56761 in the wild and no public exploit code.

Affected packages and fixed versions:
- hono (npm): affected all versions; fixed in 4.12.14
- hono (npm): affected all versions; fixed in 4.12.14

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-56761/ (Markdown: https://insights.sbomify.com/CVE-2026-56761/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-56761
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-56761
- OSV: https://osv.dev/vulnerability/CVE-2026-56761

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-56761/
Summaries are generated and may contain mistakes; the official description above is the record.