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High, CVSS 8.1amended

protobuf.js: Code generation gadget after prototype pollution

CVE-2026-44291GHSA-75px-5xx7-5xc7

What to do

Vendor fix available. Upgrade each affected package to the fixed version on its release line (protobufjs 8.0.2, 7.5.6), 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

  • npm protobufjs

    Affected
    <= 7.5.5>= 8.0.0, <= 8.0.1
    Fixed in
    7.5.6, 8.0.2

Sources

Severity and exploitation
Exploitation
No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.
CVSS
8.1 · CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS
  • CVE-2026-44291: 0.50% estimated exploitation activity in the next 30 days; percentile 42.88 (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 protobufjs used plain objects with inherited prototypes for internal type lookup tables used by generated encode and decode functions. If Object.prototype had already been polluted, those lookup tables could resolve attacker-controlled inherited properties as valid protobuf type information. This could cause attacker-controlled strings to be emitted into generated JavaScript code. Impact An attacker who can first trigger a prototype pollution vulnerability may be able to influence generated protobufjs encode or decode functions in a way that can lead to arbitrary JavaScript execution. This issue requires a separate prototype pollution primitive before protobufjs is invoked. Applications without a reachable prototype pollution primitive are not directly exploitable through this issue alone. Preconditions - The application or one of its dependencies must allow an attacker to pollute Object.prototype. - The polluted property must affect protobufjs internal type lookup behavior.…

Dates and revisions
Published by the source
Last modified by the source
Source last checked
  1. Revision 2 · amended ·

    Amended from ghsa record GHSA-75px-5xx7-5xc7

  2. Revision 1 · created ·

    Published from osv record GHSA-75px-5xx7-5xc7

Agent brief

Preview the exact text before you copy it. Commands are read-only suggestions; review them before running anything.

# Patch Next advisory brief: CVE-2026-44291

Advisory: protobuf.js: Code generation gadget after prototype pollution
IDs: CVE-2026-44291, GHSA-75px-5xx7-5xc7
Record: https://patchnext.com/advisories/cve-2026-44291 (revision 2, source checked 26 Oct 2026, 12:52 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 8.1)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: protobufjs 8.0.2, 7.5.6. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm protobufjs: affected <= 7.5.5; >= 8.0.0, <= 8.0.1; fixed in 7.5.6, 8.0.2

## Suggested inspection (read-only)
- `npm ls protobufjs --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 protobufjs.
- 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-75px-5xx7-5xc7 (OSV record GHSA-75px-5xx7-5xc7 lists affected ranges: npm protobufjs >=0 =8.0.0 <8.0.2 (fixed))
- Verified: https://github.com/advisories/GHSA-75px-5xx7-5xc7 (GitHub-reviewed advisory GHSA-75px-5xx7-5xc7 lists affected ranges: npm protobufjs >=0 =8.0.0 <=8.0.1)

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