protobufjs has overlong UTF-8 decoding

Exploitation

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

CVSS

5.3 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

EPSS

• CVE-2026-44288: 0.30% estimated exploitation activity in the next 30 days; percentile 22.87 (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 protobufjs includes a minimal UTF-8 decoder used in non-Node and fallback decoding paths. The affected decoder accepted overlong UTF-8 byte sequences and decoded them to their canonical characters instead of replacing them. The issue concerns overlong encodings and code points outside the Unicode range. protobufjs may still accept some non-strict UTF-8 input for compatibility, so applications should not rely on protobufjs as a general-purpose strict UTF-8 validator. Impact An attacker who can provide protobuf binary data decoded through the affected UTF-8 path may be able to bypass application-level checks that inspect raw bytes before protobuf string decoding. For example, bytes that do not contain certain ASCII characters could decode to strings containing those characters. The practical impact depends on downstream application validation and how decoded strings are used. Node.js Buffer-backed decoding paths are not directly affected when they use Node's native UTF-8…

Published by the source

12 May 2026, 15:00 UTC

Last modified by the source

10 Sep 2026, 03:50 UTC

Source last checked

26 Oct 2026, 12:52 UTC

1. Revision 2 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-q6x5-8v7m-xcrf

2. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-q6x5-8v7m-xcrf

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# Patch Next advisory brief: CVE-2026-44288

Advisory: protobufjs has overlong UTF-8 decoding
IDs: CVE-2026-44288, GHSA-q6x5-8v7m-xcrf
Record: https://patchnext.com/advisories/cve-2026-44288 (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: Medium (CVSS 5.3)
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; @protobufjs/utf8 1.1.1. 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
- npm @protobufjs/utf8: affected <= 1.1.0; fixed in 1.1.1

## 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`.
- `npm ls @protobufjs/utf8 --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, @protobufjs/utf8.
- 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-q6x5-8v7m-xcrf (OSV record GHSA-q6x5-8v7m-xcrf lists affected ranges: npm protobufjs >=0 =8.0.0 =0 <1.1.1 (fixed))
- Verified: https://github.com/advisories/GHSA-q6x5-8v7m-xcrf (GitHub-reviewed advisory GHSA-q6x5-8v7m-xcrf lists affected ranges: npm protobufjs >=0 =8.0.0 =0 <=1.1.0)

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