CVE-2026-54269 protobufjs: Schema-derived names can shadow runtime-significant properties
Attackers can cause denial of service in protobufjs by using schema names that shadow internal runtime properties, leading to exceptions or infinite recursion.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-54269?
CVE-2026-54269 is a medium-severity vulnerability in protobufjs protobuf.js, published on 22 Jun 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official 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.
Which versions are affected by CVE-2026-54269?
8 open source packages ship an affected version, including protobufjs and protobufjs-cli. It affects 2 products.
| Package | Affected | Fixed in |
|---|---|---|
protobufjs npm | All versions | 7.6.3 |
protobufjs npm | All versions | 7.6.3 |
protobufjs npm | From 8.0.0 | 8.6.0 |
protobufjs npm | From 8.0.0 | 8.6.0 |
protobufjs-cli npm | All versions | 1.3.3 |
protobufjs-cli npm | All versions | 1.3.3 |
2 more packages
protobufjs-cli npm | From 2.0.0 | 2.5.1 |
protobufjs-cli npm | From 2.0.0 | 2.5.1 |
Products include Protobufjs Project Protobufjs, Protobufjs Project Protobufjs-Cli.
How do I fix CVE-2026-54269?
Upgrade protobufjs to a fixed version for your release line: 7.6.3 or 8.6.0.
Is CVE-2026-54269 being exploited?
There is no known exploitation of CVE-2026-54269 in the wild and no public exploit code.
Other vulnerabilities in protobufjs protobuf.js
- CVE-2023-36665 protobufjs Prototype Pollution vulnerability
- CVE-2026-41242 protobufjs has an arbitrary code execution issue
- CVE-2022-25878 Prototype Pollution
- CVE-2026-44291 protobufjs: Code generation gadget after prototype pollution
- CVE-2026-44293 protobufjs: Code injection through bytes field defaults in generated toObject code
Sources
Also known as CLEANSTART-2026-UJ56320, CLEANSTART-2026-XE88447, CLSA-2026-1787930264, CLSA-2026-1793268960, ECHO-70eb-f73a-a7f7, GHSA-f38q-mgvj-vph7 and 15 more.