CVE-2026-44457 — hono
MEDIUMCVE-2026-44457 is a medium-severity (CVSS 5.3) CWE-524 vulnerability in hono. A fix is available for hono — see the affected versions and patch details below.
Hono: Cache Middleware ignores Vary: Authorization / Vary: Cookie leading to cross-user cache leakage
Exploitation Status
No confirmed exploitation observed yet
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-44457.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
CVE-2026-44457 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 379,145 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.
hononpmDescription
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 user-specific data present in the response body
- Inconsistent or incorrect behavior in user-specific endpoints
This issue affects applications that use the Cache Middleware on endpoints whose responses vary by Authorization or Cookie and that do not also set Cache-Control: private.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | hono | all versions | 4.12.18npm install hono@4.12.18 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for hono, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update hono to 4.12.18 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-44457 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2026-44457 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2026-44457. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2026-44457 in your dependencies?
O3 Security finds CVE-2026-44457 across npm dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.