Instance prototype alteration via unfiltered __proto__ copy
Published May 13, 2026 · Updated May 13, 2026
Prototype injection in protobuf.js before 7.5.6 and 8.0.0 through 8.0.1 allows remote attackers to alter a message instance. Generated constructors copy every enumerable property from a supplied plain object without rejecting an own proto key, changing only the resulting object's prototype rather than Object.prototype. Exploitation requires an application to pass an attacker-influenced object into a constructor or creation helper; binary-only decoding and trusted construction are not directly affected.
Summary
What happened
Prototype injection in protobuf.js before 7.5.6 and 8.0.0 through 8.0.1 allows remote attackers to alter a message instance. Generated constructors copy every enumerable property from a supplied plain object without rejecting an own proto key, changing only the resulting object's prototype rather than Object.prototype. Exploitation requires an application to pass an attacker-influenced object into a constructor or creation helper; binary-only decoding and trusted construction are not directly affected.
The record
- CVE
- CVE-2026-44292
- Published
- May 13, 2026
- Updated
- May 13, 2026
- Vendor
- protobufjs
- Product
- protobuf.js
- Classifications
- CWE-1321
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- May 13, 2026CVE publishedPublication date reported by the CVE source.
- May 13, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=< 7.5.6
- Affected versionversion=>= 8.0.0, < 8.0.2
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
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Weakness, pattern, technique
Public exploit references
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Technologies
Your stack
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Your stack
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