GHSA-p77w-8qqv-26rm — hono
MEDIUMGHSA-p77w-8qqv-26rm 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's 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 GHSA-p77w-8qqv-26rm.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
GHSA-p77w-8qqv-26rm by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.
Where this sits among everything scored
Of 379,842 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.
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 |
Affected Products
honohonoDetection & 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 GHSA-p77w-8qqv-26rm 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.
Frequently Asked Questions
Is GHSA-p77w-8qqv-26rm in your dependencies?
Find it across npm, including transitive dependencies.