CVE-2026-44455
ADVISORY - githubSummary
Summary
Improper handling of JSX element tag names in hono/jsx allowed unvalidated tag names to be directly inserted into the generated HTML output.
When untrusted input is used as a tag name via the programmatic jsx() or createElement() APIs during server-side rendering, specially crafted values may break out of the intended element context and inject unintended HTML.
Details
When rendering JSX elements to HTML strings, attribute values are escaped and attribute names are validated. However, element tag names were previously inserted into the output without validation.
If a tag name contains characters such as <, >, quotes, or whitespace, it may alter the structure of the generated HTML.
For example, malformed tag names can:
- Break out of the intended element and introduce unintended HTML elements
- Inject attributes or event handlers into the rendered output
This issue arises when untrusted input (such as query parameters or database content) is used as JSX tag names via jsx() or createElement() during server-side rendering.
Impact
An attacker who can control tag names used in JSX rendering may inject unintended HTML into the generated output.
This may lead to:
- Injection of unexpected HTML elements or attributes
- Corruption of the HTML structure
- Cross-site scripting (XSS) when combined with unsafe usage patterns
This issue only affects applications that construct JSX tag names from untrusted input. Applications using static or allowlisted tag names are not affected.
Common Weakness Enumeration (CWE)
Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection')
GitHub
1.6
CVSS SCORE
4.7medium| Package | Type | OS Name | OS Version | Affected Ranges | Fix Versions |
|---|---|---|---|---|---|
| hono | npm | - | - | <4.12.16 | 4.12.16 |
CVSS:3 Severity and metrics
The CVSS metrics represent different qualitative aspects of a vulnerability that impact the overall score, as defined by the CVSS Specification.
The vulnerable component is bound to the network stack, but the attack is limited at the protocol level to a logically adjacent topology. This can mean an attack must be launched from the same shared physical (e.g., Bluetooth or IEEE 802.11) or logical (e.g., local IP subnet) network, or from within a secure or otherwise limited administrative domain (e.g., MPLS, secure VPN to an administrative network zone). One example of an Adjacent attack would be an ARP (IPv4) or neighbor discovery (IPv6) flood leading to a denial of service on the local LAN segment (e.g., CVE-2013-6014).
A successful attack depends on conditions beyond the attacker's control, requiring investing a measurable amount of effort in research, preparation, or execution against the vulnerable component before a successful attack.
The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files of the vulnerable system to carry out an attack.
Successful exploitation of this vulnerability requires a user to take some action before the vulnerability can be exploited. For example, a successful exploit may only be possible during the installation of an application by a system administrator.
An exploited vulnerability can affect resources beyond the security scope managed by the security authority of the vulnerable component. In this case, the vulnerable component and the impacted component are different and managed by different security authorities.
There is some loss of confidentiality. Access to some restricted information is obtained, but the attacker does not have control over what information is obtained, or the amount or kind of loss is limited. The information disclosure does not cause a direct, serious loss to the impacted component.
Modification of data is possible, but the attacker does not have control over the consequence of a modification, or the amount of modification is limited. The data modification does not have a direct, serious impact on the impacted component.
There is no impact to availability within the impacted component.
Chainguard
CGA-5jwv-wvrm-7qxq
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