# protobuf.js: Code injection through bytes field defaults in… 📦 npm Not in CISA KEV # protobuf.js: Code injection through bytes field defaults in generated toObject codeGHSA-66ff-xgx4-vchm GHSA-66ff-xgx4-vchm is a Code Injection vulnerability in protobufjs. A fix is available for protobufjs — see the affected versions and patch details below. Also known as[CVE-2026-44293](/vulnerability/CVE-2026-44293) Published May 12, 2026 Updated Sep 10, 2026 Affected 2 pkgs Patched 2 / 2 Exploits None indexed Exploitation data as of Nov 9, 2026 · OSV.dev, NVD, FIRST.org (EPSS) ## Exploitation Status ### No confirmed exploitation observed yet - A successful exploit gives an attacker total control of the affected component, not partial access. - CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment. Exploitation and automatability from CISA’s SSVC triage for GHSA-66ff-xgx4-vchm. ## EPSS Exploitation Probability [via FIRST.org ↗](https://www.first.org/epss/) 0.4%probability of exploitation in next 30 days Lower Risk0.00% Lower risk than most CVEs35th percentile — riskier than 35% of all scored CVEsHighest risk 0.00%0.41%0.82%1.23%0.1%0.4%Jun 26Sep 26Nov 26 Probability of exploitation in the next 30 days, from [FIRST.org EPSS](https://www.first.org/epss/). ## Real-World Exposure 2 pkgs affected How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched. 6Kother npm packages depend on this — each one inherits the vulnerability until it's patched upstream `protobufjs`npm 123.5Mdownloads / week ## Description ### Summary 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. ### Impact An attacker who can provide or influence a protobuf descriptor may be able to execute arbitrary JavaScript in the context of the process using protobufjs. This requires the application to load an attacker-controlled schema or descriptor and then convert a message of the affected type with defaults enabled. Applications that only use trusted, application-defined schemas are not directly affected by this issue. ### Preconditions - The application must allow an attacker to control or influence a protobuf JSON descriptor or equivalent reflected schema. - The descriptor must define a `bytes` field with an attacker-controlled default value. - The application must call `toObject` with defaults enabled for the affected type. ### Workarounds Do not load protobuf schemas or JSON descriptors from untrusted sources with affected versions. If untrusted schemas must be accepted, validate or restrict field options before loading them and run schema processing in an isolated environment. ## Affected Packages 2 total 2 fixed Ecosystem Package Vulnerable range Fix 📦npm `protobufjs` all versions 7.5.6`npm install protobufjs@7.5.6` 📦npm `protobufjs` ≥ 8.0.0&&< 8.0.2 8.0.2`npm install protobufjs@8.0.2` ## Affected Products 1 product · 2 configurations Application `protobufjs`protobufjs\_project ≥ 8.0.0 && < 8.0.2 range ## Detection & mitigation playbook Open-source dependency 1. ### Detect Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for protobufjs, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version. 2. ### Fix Update protobufjs to 7.5.6 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-66ff-xgx4-vchm is resolved across your whole dependency graph. 3. ### Workarounds Stop passing untrusted input into the interpreter or shell: call the affected binary with an argument array rather than a composed command string, reject anything outside a strict allowlist of expected values, and run the component under an account that cannot reach beyond the work it legitimately does. ## Fixing This On Your OS If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project. Red HatImportant This is an Important flaw affecting Red Hat products that incorporate the protobufjs library. protobufjs is vulnerable to arbitrary code execution when compiling protobuf definitions into JavaScript. During generation of the toObject conversion function, a schema-controlled default value on a bytes field that is not a… Workaround published by Red Hat > Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability. Source: [Red Hat security advisory for GHSA-66ff-xgx4-vchm](https://access.redhat.com/security/cve/ghsa-66ff-xgx4-vchm) (CC BY 4.0) Product Fixed in Advisory Red Hat Ansible Automation Platform 2.6 for RHEL 9 `automation-platform-ui-0:2.6.10-1.el9ap` [RHSA-2026:34160](https://access.redhat.com/errata/RHSA-2026:34160) Red Hat Enterprise Linux 10 `rh-podman-desktop-0:1.1.1-1.el10_2` [RHSA-2026:37385](https://access.redhat.com/errata/RHSA-2026:37385) Red Hat Ansible Automation Platform 2.6 `ansible-automation-platform-26/gateway-rhel9:1782761510` [RHSA-2026:34374](https://access.redhat.com/errata/RHSA-2026:34374) Red Hat Developer Hub 1.9 `rhdh/rhdh-hub-rhel9:1781187342` [RHSA-2026:26234](https://access.redhat.com/errata/RHSA-2026:26234) Red Hat OpenShift AI 3.4 `rhoai/odh-dashboard-rhel9:1787347991` [RHSA-2026:60520](https://access.redhat.com/errata/RHSA-2026:60520) Red Hat OpenShift AI 3.4 `rhoai/odh-mod-arch-eval-hub-rhel9:1791861214` [RHSA-2026:84734](https://access.redhat.com/errata/RHSA-2026:84734) Red Hat OpenShift Container Platform 4.18 `openshift4/ose-console-rhel9:1787031447` [RHSA-2026:57487](https://access.redhat.com/errata/RHSA-2026:57487) Red Hat OpenShift Container Platform 4.19 `openshift4/ose-console-rhel9:1786486822` [RHSA-2026:54555](https://access.redhat.com/errata/RHSA-2026:54555) ## Frequently Asked Questions \## Summary 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. ## Impact An attacker who can provide or influence a protobuf descriptor may be able to execute arbitrary JavaScript in the context of the process using protobufjs. This requires the application to load an attacker-controlled schema or descriptor and then convert a O3 Security · Impact-Aware SCA ### Is GHSA-66ff-xgx4-vchm in your dependencies? Find it across npm, including transitive dependencies. [Scan my dependencies](/book-demo) [How O3 SCA works](/impact-aware-sca)