oRPC: Vary Header Injection in CORS Plugin leading to potential Cache/CORS Bypass

Exploitation

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

CVSS 4.0

6.3 · CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N · score source

EPSS

• CVE-2026-77360: 0.54% estimated exploitation activity in the next 30 days; percentile 45.65 (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 A flaw in the CORS plugin allowed the incoming request's Vary header to be reflected into the response, letting a client influence a header that should be controlled solely by the server. Details The CORS plugin previously copied the request's Vary header directly onto the response instead of treating Vary as a response-only header. Because Vary tells downstream caches and proxies how to key their cached responses, this allowed a client to inject arbitrary values into the response's Vary header, potentially distorting cache-key behavior in shared caches/CDNs sitting in front of an oRPC server and leading to inconsistent CORS enforcement for other clients. Practical impact is limited to deployments where a shared cache or reverse proxy keys on the Vary header; the real-world effect depends on the caching layer's configuration. Impact May cause cache key pollution and inconsistent CORS enforcement in setups that rely on shared/edge caches keying on Vary. No direct…

Published by the source

17 Sep 2026, 14:52 UTC

Last modified by the source

17 Sep 2026, 15:00 UTC

Source last checked

26 Oct 2026, 13:02 UTC

1. Revision 4 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-j9v4-rhgr-4m5f

2. Revision 3 · amended · 24 Oct 2026

   Reviewed OSV alias/range/CVSS4 correction; package source scopes and original publication preserved. No customer finding resolved.

3. Revision 2 · amended · 24 Oct 2026

   Amended from osv record GHSA-j9v4-rhgr-4m5f

4. Revision 1 · created · 23 Oct 2026

   Published from ghsa record GHSA-j9v4-rhgr-4m5f

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# Patch Next advisory brief: CVE-2026-77360

Advisory: oRPC: Vary Header Injection in CORS Plugin leading to potential Cache/CORS Bypass
IDs: CVE-2026-77360, GHSA-j9v4-rhgr-4m5f
Record: https://patchnext.com/advisories/cve-2026-77360 (revision 4, source checked 26 Oct 2026, 13:02 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 6.3)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: @orpc/server 1.14.8. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm @orpc/server: affected <= 1.14.7; fixed in 1.14.8

## Suggested inspection (read-only)
- `npm ls @orpc/server --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 @orpc/server.
- 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://github.com/advisories/GHSA-j9v4-rhgr-4m5f (GitHub-reviewed advisory GHSA-j9v4-rhgr-4m5f lists affected ranges: npm @orpc/server >=0 <=1.14.7)
- Verified: https://osv.dev/vulnerability/GHSA-j9v4-rhgr-4m5f (OSV record GHSA-j9v4-rhgr-4m5f lists affected ranges: npm @orpc/server >=0 <1.14.8 (fixed))

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