Hono's Cache Middleware ignores Vary: Authorization / Vary: Cookie leading to cross-user cache leakage

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

5.3 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

EPSS

• CVE-2026-44457: 0.20% estimated exploitation activity in the next 30 days; percentile 9.57 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary Cache Middleware does not skip caching for responses that declare per-user variance via Vary: Authorization or Vary: Cookie. As a result, a response cached for one authenticated user may be served to subsequent requests from different users. Details The Cache Middleware skips caching when a response carries Vary: , certain Cache-Control directives (private, no-store, no-cache), or Set-Cookie. However, Vary: Authorization and Vary: Cookie — the standard signals defined in RFC 9110 / RFC 9111 to indicate per-user responses — are not treated as cache-skip reasons. This issue arises when applications use the Cache Middleware on endpoints that return user-specific data and rely on Vary: Authorization or Vary: Cookie to scope the response per user, without also setting Cache-Control: private. Impact A user may receive a cached response that was originally generated for a different authenticated user. This may lead to: - Disclosure of personally identifiable information or other…

Published by the source

9 May 2026, 00:28 UTC

Last modified by the source

10 Sep 2026, 03:51 UTC

Source last checked

26 Oct 2026, 12:52 UTC

1. Revision 2 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-p77w-8qqv-26rm

2. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-p77w-8qqv-26rm

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# Patch Next advisory brief: CVE-2026-44457

Advisory: Hono's Cache Middleware ignores Vary: Authorization / Vary: Cookie leading to cross-user cache leakage
IDs: CVE-2026-44457, GHSA-p77w-8qqv-26rm
Record: https://patchnext.com/advisories/cve-2026-44457 (revision 2, source checked 26 Oct 2026, 12:52 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 5.3)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: hono 4.12.18. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm hono: affected < 4.12.18; fixed in 4.12.18

## Suggested inspection (read-only)
- `npm ls hono --all`: lists every installed copy and version, including transitive ones. Run in the project root after `npm ci`.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on hono.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-p77w-8qqv-26rm (OSV record GHSA-p77w-8qqv-26rm lists affected ranges: npm hono >=0 <4.12.18 (fixed))
- Verified: https://github.com/advisories/GHSA-p77w-8qqv-26rm (GitHub-reviewed advisory GHSA-p77w-8qqv-26rm lists affected ranges: npm hono >=0 <4.12.18)

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