CVE-2026-44291

Description

protobufjs compiles protobuf definitions into JavaScript (JS) functions. Prior to 7.5.6 and 8.0.2, protobufjs used plain objects with inherited prototypes for internal type lookup tables used by generated encode and decode functions. If Object.prototype had already been polluted, those lookup tables could resolve attacker-controlled inherited properties as valid protobuf type information. This could cause attacker-controlled strings to be emitted into generated JavaScript code. This vulnerability is fixed in 7.5.6 and 8.0.2.

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CVSS v3.1 Score

8.1

HIGH

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS — Exploit Prediction

0.0002

Probability of exploitation

0.07%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-94 CWE-94

Affected Products

Vendor	Product	Versions
protobufjs_project	protobufjs	< 7.5.6
protobufjs_project	protobufjs	8.0.0 — 8.0.2

References

Advisories & Patches

https://github.com/protobufjs/protobuf.js/security/advisories/GHSA-75px-5xx7-5xc7

Frequently Asked Questions

What is CVE-2026-44291? +

protobufjs compiles protobuf definitions into JavaScript (JS) functions. Prior to 7.5.6 and 8.0.2, protobufjs used plain objects with inherited prototypes for internal type lookup tables used by generated encode and decode functions. If Object.prototype had already been polluted, those lookup tables could resolve attacker-controlled inherited properties as valid protobuf type information. This could cause attacker-controlled strings to be emitted into generated JavaScript code. This vulnerability is fixed in 7.5.6 and 8.0.2. It has a CVSS v3.1 base score of 8.1 (HIGH).

How severe is CVE-2026-44291? +

CVE-2026-44291 has a CVSS v3.1 score of 8.1 out of 10, rated HIGH. This is a high-severity vulnerability that should be prioritized for patching. The EPSS score is 0.0002, placing it in the 0th percentile for exploitation probability.

What products are affected by CVE-2026-44291? +

CVE-2026-44291 affects products from protobufjs_project, specifically: protobufjs. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2026-44291? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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