VulnerabilityPublished 27 Jan 2026

CVE-2026-24771: honojs hono · Cross-site Scripting

Affects honojs honoSource CVE Database V5

Not known to be exploited · CVSS 4.7 Medium : upgrade to 4.11.7 when convenient.

Data as of 26 Oct 2026, 14:05 UTC

CVSS 3.1 base score

4.7Medium

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.3% chance of exploitation in 30 days – higher than 31% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 4.11.7

CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:L/I:L/A:N

Attack Vector: Network
Attack Complexity: High
Privileges Required: None
User Interaction: Required
Scope: Changed
Confidentiality: Low
Integrity: Low
Availability: None

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: High: A successful attack depends on conditions beyond the attacker's control. That is, a successful attack cannot be accomplished at will, but requires the attacker to invest in some measurable amount of effort in preparation or execution against the vulnerable component before a successful attack can be expected. For example, a successful attack may require an attacker to: gather knowledge about the environment in which the vulnerable target/component exists; prepare the target environment to improve exploit reliability; or inject themselves into the logical network path between the target and the resource requested by the victim in order to read and/or modify network communications (e.g., a man in the middle attack).
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: Required: Successful exploitation of this vulnerability requires a user to take some action before the vulnerability can be exploited.
Scope: Changed: 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.
Confidentiality: Low: 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.
Integrity: Low: 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.
Availability: None: There is no impact to availability within the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 27 Jan 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade honojs hono to 4.11.7.

Affected software

Product	Affected	Fixed in
honojshono	Affected <4.11.7	Fixed in 4.11.7
npmhono`pkg:npm/hono`Other threats	Affected <4.11.7	Fixed in 4.11.7

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

Upgrade all hono framework instances to version 4.11.7 or later immediately to apply the official patch that neutralizes the XSS vulnerability in the ErrorBoundary component.
Conduct a thorough code review of all custom error handling and rendering logic to ensure that no user-controlled input is rendered as raw HTML without proper sanitization or escaping.
Implement Content Security Policy (CSP) headers to restrict the execution of unauthorized scripts and reduce the impact of potential XSS attacks.
Employ automated security testing tools that can detect XSS vulnerabilities in development and staging environments, focusing on error boundary and JSX rendering components.
Educate developers on secure coding practices related to input validation and output encoding, especially in error handling contexts.
Monitor web application logs and user reports for suspicious activity that might indicate attempted exploitation.
If upgrading immediately is not feasible, apply temporary mitigations such as disabling or restricting the use of the vulnerable ErrorBoundary component or sanitizing inputs before they reach it.

Description

Hono is a Web application framework that provides support for any JavaScript runtime. Prior to version 4.11.7, a Cross-Site Scripting (XSS) vulnerability exists in the `ErrorBoundary` component of the hono/jsx library. Under certain usage patterns, untrusted user-controlled strings may be rendered as raw HTML, allowing arbitrary script execution in the victim's browser. Version 4.11.7 patches the issue.

Impact

For European organizations, this vulnerability poses a risk primarily to web applications built using the hono framework versions prior to 4.11.7. Successful exploitation could lead to client-side script execution, enabling attackers to steal session cookies, perform actions on behalf of users, or deface web content. This can result in loss of user trust, data breaches, and regulatory non-compliance under GDPR due to compromised user data confidentiality. The medium severity score reflects that exploitation requires user interaction and has high complexity, limiting widespread automated attacks. However, targeted attacks against high-value applications or services remain a concern. Organizations in sectors such as finance, e-commerce, and public services that rely on hono-based web applications are particularly vulnerable. The impact on availability is minimal, but integrity and confidentiality risks are notable. Given the increasing use of JavaScript frameworks in Europe, the vulnerability could affect a broad range of applications if not addressed.

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') (opens in a new tab)
Base weaknessLikelihood of exploit: HighCWE Top 25 (2025): #1OWASP Top 10 A05:2025: Injection (opens in a new tab)
The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users.
Architecture and Design · Libraries or Frameworks
Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.
Implementation · Architecture and Design
Understand the context in which your data will be used and the encoding that will be expected. This is especially important when transmitting data between different components, or when generating outputs that can contain multiple encodings at the same time, such as web pages or multi-part mail messages.
Architecture and Design · Implementation · Attack Surface Reduction
Understand all the potential areas where untrusted inputs can enter your software: parameters or arguments, cookies, anything read from the network, environment variables, reverse DNS lookups, query results, request headers, URL components, e-mail, files, filenames, databases, and any external systems that provide…
OWASP Cheat Sheets
Cross Site Scripting Prevention (opens in a new tab)
DOM based XSS Prevention (opens in a new tab)
Injection Prevention (opens in a new tab)
Abuse Case (opens in a new tab)
Deserialization (opens in a new tab)
OWASP ASVS 4.0.3
V5.3.3 (opens in a new tab)
V1.5.1 (opens in a new tab)
Attack patterns
XSS Using MIME Type Mismatch (opens in a new tab)
DOM-Based XSS (opens in a new tab)
Reflected XSS (opens in a new tab)
Stored XSS (opens in a new tab)
Cross-Site Scripting (XSS) (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 27 Jan 2026, 20:05 UTC

WeaknessesCWE-79

Technical details

References

Community reviews

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