CVE-2026-44293: protobufjs: Code injection through bytes field defaults in generated toObject code

Severity: high (CVSS 8.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.4% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-05-13 · updated 2026-09-09
Weakness: CWE-94

Description

protobufjs compiles protobuf definitions into JavaScript (JS) functions. Prior to 7.5.6 and 8.0.2, 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. This vulnerability is fixed in 7.5.6 and 8.0.2.

Affected products

protobufjs: before 7.5.6; from 8.0.0 before 8.0.2 — fixed in 7.5.6, 8.0.2

How to fix

Upgrade to a fixed version: protobufjs 7.5.6, 8.0.2. Check the vendor advisory for mitigations.

References

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