Is CVE-2026-54269 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-54269 being exploited in the wild.

How severe is CVE-2026-54269?

Medium severity, with a CVSS score of 5.3, published 22 June 2026.

Which products and versions are affected?

protobufjs (npm) SEMVER:introduced=0,fixed=7.6.3; protobufjs-cli (npm) SEMVER:introduced=2.0.0,fixed=2.5.1.

Is there a fix for CVE-2026-54269?

Yes. protobufjs (npm): upgrade to 7.6.3 or later; protobufjs-cli (npm): upgrade to 2.5.1 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

How is CVE-2026-54269 attacked?

It is attacked over the network, in a software library.

Am I affected by CVE-2026-54269?

Check whether you run protobufjs (npm) or protobufjs-cli (npm) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2026-54269: protobufjs property shadowing and uncontrolled recursion

CVE-2026-54269 · Severity: medium · CVSS 5.3 · Published 2026-06-22

A vulnerability in the protobufjs library, which is used to handle data serialization in JavaScript applications, can allow an attacker to crash a service. By providing a specially crafted data schema with conflicting names, an attacker can trigger errors or infinite loops that make the application unresponsive. This primarily impacts the availability of services that process untrusted data schemas.

Technologies: protobufjs (npm), protobufjs-cli (npm). Vendors: npm.

Quick answers

Is CVE-2026-54269 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-54269 being exploited in the wild.
How severe is CVE-2026-54269?: Medium severity, with a CVSS score of 5.3, published 22 June 2026.
Which products and versions are affected?: protobufjs (npm) SEMVER:introduced=0,fixed=7.6.3; protobufjs-cli (npm) SEMVER:introduced=2.0.0,fixed=2.5.1.
Is there a fix for CVE-2026-54269?: Yes. protobufjs (npm): upgrade to 7.6.3 or later; protobufjs-cli (npm): upgrade to 2.5.1 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-54269 attacked?: It is attacked over the network, in a software library.
Am I affected by CVE-2026-54269?: Check whether you run protobufjs (npm) or protobufjs-cli (npm) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

How to fix

protobufjs (npm): upgrade to 7.6.3 or later
```
npm install protobufjs@7.6.3
```
protobufjs-cli (npm): upgrade to 2.5.1 or later
```
npm install protobufjs-cli@2.5.1
```

Technical details

The vulnerability exists because protobufjs fails to properly sanitize or isolate schema-derived names that collide with internal runtime helper properties. Specifically, names such as 'hasOwnProperty', '$type', or service methods resulting in 'rpcCall' can shadow internal functions or metadata. When these names are encountered during decoding, verification, or RPC invocation, the library may attempt to execute or read schema-controlled data as if it were a trusted internal helper. This results in deterministic exceptions or uncontrolled recursion (CWE-674), leading to a denial of service. The issue is exploitable if an application loads untrusted schemas or JSON descriptors. Patches are available in versions 7.6.3 and 8.6.0.

Affected products

protobufjs protobufjs < 7.6.3, >= 8.0.0, < 8.6.0
protobufjs protobufjs-cli <= 1.3.2, >= 2.0.0, <= 2.5.0

Identifiers

CVE-2026-54269
GHSA-f38q-mgvj-vph7

Timeline

2026-06-12: advisory: GitHub Security Advisory published
2026-06-22: disclosed: CVE published to NVD

References

https://github.com/protobufjs/protobuf.js/security/advisories/GHSA-f38q-mgvj-vph7

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