# CVE-2026-71850: Hono hono/jsx cross-user data disclosure in memo function

Source: https://junglewise.ai/threats/cve-2026-71850-hono-hono-jsx-cross-user-data-disclosure-in-memo-function  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-08-07. Updated: 2026-08-07  
License: CC BY 4.0 with a link back

CVE-2026-71850 · Severity: medium · CVSS 4.8 · Published 2026-08-07

A vulnerability in the Hono web framework could cause a user to see another person's private information. This happens because the system incorrectly saves and reuses parts of a webpage that were originally created for a different user. As a result, sensitive data like account details or security tokens could be accidentally shown to the wrong person.

Technologies: [hono (npm)](https://junglewise.ai/threats/technologies/hono). Vendors: [npm](https://junglewise.ai/threats/vendors/npm).

## Quick answers

**Is CVE-2026-71850 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-71850 being exploited in the wild.

**How severe is CVE-2026-71850?** Medium severity, with a CVSS score of 4.8, published 7 August 2026.

**Which products and versions are affected?** hono (npm) >= 3.8.0, < 4.12.34, SEMVER:introduced=3.8.0,fixed=4.12.34.

**Is there a fix for CVE-2026-71850?** Yes. hono (npm): upgrade to 4.12.34 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-71850 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-71850?** Check whether you run hono (npm) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- hono (npm): upgrade to 4.12.34 or later

  ```sh
  npm install hono@4.12.34
  ```


## Technical details

The `memo()` function in `hono/jsx` implements a caching mechanism that compares components based solely on their props. However, it fails to account for request-scoped ambient context (such as JSX Context, `useRequestContext`, or `getContext`) during this comparison. If a memoized component reads user-specific data from the context rather than through props, the rendered HTML from a previous request may be served to a subsequent user if the props match. This leads to a session leakage vulnerability (CWE-488) where sensitive data like CSRF tokens or profile information is disclosed across requests on the same warm instance. The issue is fixed in version 4.12.34.

## Affected products

- honojs hono >= 3.8.0, < 4.12.34

## Identifiers

- CVE-2026-71850
- GHSA-f23p-vx2j-j53r

## Timeline

- 2026-08-03: patched: Fix released in version 4.12.34
- 2026-08-07: advisory: GitHub Advisory published

## References

- [https://api.github.com/users/raster0x2a](https://api.github.com/users/raster0x2a)
- [https://github.com/raster0x2a](https://github.com/raster0x2a)
- [https://api.github.com/users/raster0x2a/gists%7B/gist_id%7D](https://api.github.com/users/raster0x2a/gists%7B/gist_id%7D)
- [https://api.github.com/users/raster0x2a/repos](https://api.github.com/users/raster0x2a/repos)
- [https://avatars.githubusercontent.com/u/64038390?v=4](https://avatars.githubusercontent.com/u/64038390?v=4)
- [https://api.github.com/users/raster0x2a/events%7B/privacy%7D](https://api.github.com/users/raster0x2a/events%7B/privacy%7D)

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