protobufjs: Prototype injection in generated message constructors

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protobufjs compiles protobuf definitions into JavaScript (JS) functions. Prior to 7.5.6 and 8.0.2, protobufjs generated message constructors copied enumerable properties from a provided properties object without filtering the __proto__ key. If an application constructed a message from an attacker-controlled plain object, an own enumerable __proto__ property could alter the prototype of that individual message instance. This vulnerability is fixed in 7.5.6 and 8.0.2.

Source published

13 May 2026 14:42:55 UTC

Source modified

18 May 2026 14:01:31 UTC

Saved here

23 Oct 2026 15:48:27 UTC

Source terms

CVE Program Terms of Use

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Source: cve-program · CVE Program Terms of Use. The publisher's wording is preserved. ChangeIntel groups the information and labels changes. The JSON record includes additional source fields.

CVSS 3.1 · 5.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

protobufjs compiles protobuf definitions into JavaScript (JS) functions. Prior to 7.5.6 and 8.0.2, protobufjs generated message constructors copied enumerable properties from a provided properties object without filtering the __proto__ key. If an application constructed a message from an attacker-controlled plain object, an own enumerable __proto__ property could alter the prototype of that individual message instance. This vulnerability is fixed in 7.5.6 and 8.0.2.

Source published

May 13, 2026, 2:42:55 PM (timezone not stated)

Source modified

May 18, 2026, 2:01:31 PM (timezone not stated)

Saved here

13 Nov 2026 12:59:56 UTC

Source terms

ENISA EUVD · source terms and attribution apply

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Source: euvd · ENISA EUVD · source terms and attribution apply. The publisher's wording is preserved. ChangeIntel groups the information and labels changes. The JSON record includes additional source fields.

EUVD CVSS 3.1 · 5.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

protobufjs compiles protobuf definitions into JavaScript (JS) functions. Prior to 7.5.6 and 8.0.2, protobufjs generated message constructors copied enumerable properties from a provided properties object without filtering the __proto__ key. If an application constructed a message from an attacker-controlled plain object, an own enumerable __proto__ property could alter the prototype of that individual message instance. This vulnerability is fixed in 7.5.6 and 8.0.2.

Source published

13 May 2026 16:16:56 UTC

Source modified

11 Nov 2026 20:10:00 UTC

Saved here

12 Nov 2026 18:19:07 UTC

Source terms

NIST NVD usage terms; underlying source attribution retained

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Source: nvd · NIST NVD usage terms; underlying source attribution retained. The publisher's wording is preserved. ChangeIntel groups the information and labels changes. The JSON record includes additional source fields.

CVSS 3.1 · [email protected] · Secondary · 5.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

## Summary protobufjs generated message constructors copied enumerable properties from a provided properties object without filtering the `__proto__` key. If an application constructed a message from an attacker-controlled plain object, an own enumerable `__proto__` property could alter the prototype of that individual message instance. ## Impact An attacker who can control the properties object passed to a generated protobufjs message constructor or creation helper may be able to modify the prototype chain of the resulting message instance. This is a per-instance prototype injection issue. It does not pollute `Object.prototype` or other global prototypes. The impact depends on downstream application behavior, such as relying on inherited properties, prototype methods, or `instanceof` checks for message objects. Applications that only decode binary protobuf data, or that construct messages from trusted application-defined objects, are not directly affected by this issue. ## Preconditions - The application must allow an attacker to control or influence a plain object used to construct a protobufjs message. - The object must contain an own enumerable `__proto__` property, for example from parsed JSON input. - The application must pass that object to a generated message constructor or creation helper that copies arbitrary enumerable properties. ## Workarounds Do not pass attacker-controlled plain objects directly to generated message constructors with affected versions. If untrusted JSON input must be accepted, validate or sanitize object keys before constructing messages, and reject `__proto__` properties.

Source published

12 May 2026 15:01:44 UTC

Source modified

10 Sep 2026 03:50:46 UTC

Saved here

24 Oct 2026 13:17:17 UTC

Source terms

GitHub Advisory Database · CC-BY-4.0

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Source: osv · GitHub Advisory Database · CC-BY-4.0. The publisher's wording is preserved. ChangeIntel groups the information and labels changes. The JSON record includes additional source fields.

CVSS_V3 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

Publisher rating · MODERATE