protobuf.js: Code injection through bytes field defaults in generated toObject code
Summary
protobufjs generated JavaScript for toObject conversion could include an unsafe expression derived from a schema-controlled bytes field default value. A crafted descriptor with a non-string default value for a bytes field could cause attacker-controlled code to be emitted into the generated conversion function.
Impact
An attacker who can provide or influence a protobuf descriptor may be able to execute arbitrary JavaScript in the context of the process using protobufjs.
This requires the application to load an attacker-controlled schema or descriptor and then convert a message of the affected type with defaults enabled. Applications that only use trusted, application-defined schemas are not directly affected by this issue.
Preconditions
- The application must allow an attacker to control or influence a protobuf JSON descriptor or equivalent reflected schema.
- The descriptor must define a
bytesfield with an attacker-controlled default value. - The application must call
toObjectwith defaults enabled for the affected type.
Workarounds
Do not load protobuf schemas or JSON descriptors from untrusted sources with affected versions. If untrusted schemas must be accepted, validate or restrict field options before loading them and run schema processing in an isolated environment.
Affected software
Click a technology to see all vulnerabilities affecting it.
| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| npm package | protobufjs | < 7.5.6, >= 8.0.0, < 8.0.2 | 7.5.6, 8.0.2 |
References
- CVSS vector
CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N- Weakness (CWE)
CWE-94- Platform
- npm
- Package
protobufjs- Disclosed
- 12.05.2026
- Updated
- 11.10.2026 10:22
Sources and licenses
OSV / GitHub Advisory Database - GHSA-66ff-xgx4-vchm - CC BY 4.0
Vulnerability history: protobufjs
All published vulnerabilities of this package (npm package), newest first. Shows whether this is a one-off slip or a package that needs watching.
- Total entries
- 17
- First → latest
- 10.2018 07.2026
- Without a fix
- 0
- Exploited in attacks
- 0
Severity breakdown
- Critical 2
- High 6
- Medium 9
Disclosures per year
- 2018: 1
- 2019: 0
- 2020: 0
- 2021: 0
- 2022: 1
- 2023: 1
- 2024: 0
- 2025: 0
- 2026: 14
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protobuf.js: Code injection through bytes field defaults in generated toObject code this entry
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