Security Digest · Vulnerability record
CVE-2026-41242: Arbitrary code execution in protobufjs
protobufjs compiles protobuf definitions into JavaScript (JS) functions.
CVSS 9.4 Critical EPSS 1.0% · p62
Should you act?
Critical, preconditions apply
Severe if exploited, but exploitation needs conditions that may not apply to you. This signal is computed from CISA KEV, EPSS and CVSS data; it is not an editorial verdict.
- Not in CISA KEV, but CISA’s SSVC assessment records a public proof-of-concept, so attack code exists.
- EPSS 1.0%, percentile 62: FIRST’s model estimates a 1.0% chance of exploitation activity in the next 30 days, higher than 62% of all scored CVEs (moderate). EPSS is a probability, not a verdict.
- Needs an account (low (any account)). Exposure depends on who can log in.
- Only applies if your dependency tree includes
protobufjs(npm) >= 8.0.0, < 8.0.1, fixed in 8.0.1;protobufjs(npm) < 7.5.5, fixed in 7.5.5. Check your lockfile, including transitive dependencies.
What it is
protobufjs compiles protobuf definitions into JavaScript (JS) functions. In versions prior to 8.0.1 and 7.5.5, attackers can inject arbitrary code in the "type" fields of protobuf definitions, which will then execute during object decoding using that definition. Versions 8.0.1 and 7.5.5 patch the issue.
From the GitHub advisory
Summary
protobufjs could execute generated JavaScript code derived from protobuf schema metadata. When loading a crafted JSON descriptor, schema-controlled type names and type references could reach runtime code generation without sufficient validation.
Impact
An attacker who can provide a malicious protobuf definition or JSON descriptor to an application may be able to execute arbitrary JavaScript in the context of the process using protobufjs.
This requires control over the protobuf schema or descriptor being loaded. Applications that only decode messages using trusted, application-defined schemas are not directly affected by this issue.
Weakness type: CWE-94.
Product: protobufjs (npm) · Assigned by: GitHub_M · Published: 2026-04-18
Affected and fixed versions
| Ecosystem | Package | Vulnerable | First fixed |
|---|---|---|---|
| npm | protobufjs | >= 8.0.0, < 8.0.1 | 8.0.1 |
| npm | protobufjs | < 7.5.5 | 7.5.5 |
| Vendor | Product | Affected versions (per CVE record) |
|---|---|---|
| protobufjs | protobuf.js | < 7.5.5, >= 8.0.0-experimental, < 8.0.1 |
Severity scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| GitHub_M | 4.0 | 9.4 Critical | CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H |
| redhat-SADP | 3.1 | 8.8 High | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
| GitHub | 4.0 | 9.4 | CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H |
- Attack vector: network (remotely reachable)
- Attack complexity: low
- Attack requirements: none
- Privileges required: low (any account)
- User interaction: none
CVSS measures how bad a flaw is if exploited, not how likely exploitation is. Read it next to the exploitation data below.
Exploitation and urgency
- CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
- CISA SSVC assessment: exploitation poc, automatable yes, technical impact total.
- FIRST EPSS (model of 2026-10-21): 0.99% probability of exploitation activity in the next 30 days; percentile 62.
Timeline
- — GitHub-reviewed advisory GHSA-xq3m-2v4x-88gg published (critical)
- — CVE record published by GitHub_M
- — CVE record last updated
Sources and references
Original sources first. Version and fix details should always be confirmed against the vendor or project advisory.
Vendor and project advisories, patches
- access.redhat.com access.redhat.com
- access.redhat.com access.redhat.com
- access.redhat.com access.redhat.com
- access.redhat.com access.redhat.com
- access.redhat.com access.redhat.com
Vulnerability records
- GitHub Advisory GHSA-xq3m-2v4x-88gg github.com
- CVE.org record CVE-2026-41242 cve.org
- NVD entry CVE-2026-41242 nvd.nist.gov
Other references from the CVE record and advisory
- github.com github.com
- github.com github.com
- github.com github.com
- github.com github.com
- github.com github.com
- access.redhat.com access.redhat.com
- RHBZ#2459442 bugzilla.redhat.com
- security.access.redhat.com security.access.redhat.com