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Critical, CVSS 9.3amended

HAXcms: Private Key Disclosure via Broken HMAC Implementation

CVE-2026-46395GHSA-6c8g-9hfh-pq5h

What to do

Vendor fix available. Upgrade each affected package to the fixed version on its release line (@haxtheweb/haxcms-nodejs 26.0.0), 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
9.3 · CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N · score source
EPSS
  • CVE-2026-46395: 0.29% estimated exploitation activity in the next 30 days; percentile 22.19 (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.

Summary The hmacBase64() function in the HAXcms Node.js backend contains two critical cryptographic implementation errors that together allow any unauthenticated attacker to extract the system’s private signing key and forge arbitrary admin-level JSON Web Tokens (JWTs) allowing them to get full admin access with a single HTTP request. Details Bug 1: Hardcoded HMAC Key (line 2160): The function passes the literal string "0" as the HMAC signing key instead of the key parameter, making every HAXcms instance compute identical HMACs for the same input. Bug 2: Private Key Appended to Output (lines 2161- 2163): After computing the HMAC, the function concatenates the real key parameter which is "this.privateKey + this.salt", the system’s master signing secret is directly onto the output. The combined buffer is base64-encoded and returned as the token. Every base64url token produced has the same structure: 32 bytes HMAC keyed with "0" and N bytes of privateKey+salt. An attacker base64-decodes…

Dates and revisions
Published by the source
Last modified by the source
Source last checked
  1. Revision 4 · amended ·

    Amended from ghsa record GHSA-6c8g-9hfh-pq5h

  2. Revision 3 · amended ·

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

  3. Revision 2 · amended ·

    Amended from osv record GHSA-6c8g-9hfh-pq5h

  4. Revision 1 · created ·

    Published from ghsa record GHSA-6c8g-9hfh-pq5h

Agent brief

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# Patch Next advisory brief: CVE-2026-46395

Advisory: HAXcms: Private Key Disclosure via Broken HMAC Implementation
IDs: CVE-2026-46395, GHSA-6c8g-9hfh-pq5h
Record: https://patchnext.com/advisories/cve-2026-46395 (revision 4, source checked 26 Oct 2026, 12:53 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Critical (CVSS 9.3)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: @haxtheweb/haxcms-nodejs 26.0.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm @haxtheweb/haxcms-nodejs: affected <= 25.0.0; fixed in 26.0.0

## Suggested inspection (read-only)
- `npm ls @haxtheweb/haxcms-nodejs --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 @haxtheweb/haxcms-nodejs.
- 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-6c8g-9hfh-pq5h (GitHub-reviewed advisory GHSA-6c8g-9hfh-pq5h lists affected ranges: npm @haxtheweb/haxcms-nodejs >=0 <=25.0.0)
- Verified: https://osv.dev/vulnerability/GHSA-6c8g-9hfh-pq5h (OSV record GHSA-6c8g-9hfh-pq5h lists affected ranges: npm @haxtheweb/haxcms-nodejs >=0 <26.0.0 (fixed))

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