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High, CVSS 8.6amended

Uni-CLI: Legacy HTTP MCP transport accepted browser-originated localhost requests

CVE-2026-58497GHSA-v3f4-w7r7-v3hm

What to do

Vendor fix available. Upgrade each affected package to the fixed version on its release line (@zenalexa/unicli 0.225.2), redeploy, then verify what is actually installed.

This page has no inventory attached, so it cannot say whether you are affected. A vendor fix is not proof that your deployment is fixed.

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Affected packages

Sources

Severity and exploitation
Exploitation
No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.
CVSS 4.0
8.6 · CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N · score source
EPSS
  • CVE-2026-58497: 0.26% estimated exploitation activity in the next 30 days; percentile 17.20 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.
Source description

As published by the source; long descriptions are shortened.

Impact Uni-CLI versions before 0.225.2 exposed the legacy JSON-RPC-over-HTTP MCP transport on loopback without validating browser Origin headers before routing requests. A malicious web page could send a CORS simple POST request, such as text/plain, to the local /mcp endpoint and deliver a JSON-RPC body to the dispatcher. If the user had started the local MCP HTTP transport, that page could drive tools/call requests against the user's local Uni-CLI server. The Streamable HTTP transport already enforced this browser-to-localhost boundary. The legacy stateless HTTP path did not, so the two HTTP transports had drifted. This issue is about the browser-to-localhost boundary; it does not change Uni-CLI's local-code-execution trust model. Patches Version 0.225.2 fixes the issue by moving the Origin policy into a shared guard and applying it before routing in both HTTP transports. Non-loopback browser Origins are rejected with HTTP 403 before health, OAuth, or /mcp dispatch runs. Non-browser…

Dates and revisions
Published by the source
Last modified by the source
Source last checked
  1. Revision 3 · amended ·

    Amended from ghsa record GHSA-v3f4-w7r7-v3hm

  2. Revision 2 · amended ·

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

  3. Revision 1 · created ·

    Published from osv record GHSA-v3f4-w7r7-v3hm

Agent brief

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# Patch Next advisory brief: CVE-2026-58497

Advisory: Uni-CLI: Legacy HTTP MCP transport accepted browser-originated localhost requests
IDs: CVE-2026-58497, GHSA-v3f4-w7r7-v3hm
Record: https://patchnext.com/advisories/cve-2026-58497 (revision 3, source checked 26 Oct 2026, 12:56 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 8.6)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: @zenalexa/unicli 0.225.2. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm @zenalexa/unicli: affected < 0.225.2; fixed in 0.225.2

## Suggested inspection (read-only)
- `npm ls @zenalexa/unicli --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 @zenalexa/unicli.
- 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-v3f4-w7r7-v3hm (OSV record GHSA-v3f4-w7r7-v3hm lists affected ranges: npm @zenalexa/unicli >=0 <0.225.2 (fixed))
- Verified: https://github.com/advisories/GHSA-v3f4-w7r7-v3hm (GitHub-reviewed advisory GHSA-v3f4-w7r7-v3hm lists affected ranges: npm @zenalexa/unicli >=0 <0.225.2)

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