How severe is CVE-2026-42420?

No CVSS score has been assigned to CVE-2026-42420 yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by CVE-2026-42420?

CVE-2026-42420 affects the following packages: openclaw (npm). Ecosystems affected: npm.

How do I fix CVE-2026-42420?

Update openclaw to 2026.4.8 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-42420 is resolved across your whole dependency graph.

How do I detect CVE-2026-42420 in my npm dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for openclaw, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2026-42420 if there is no patch (or I can't update yet)?

If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

How does O3 Security protect against CVE-2026-42420?

O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2026-42420 can be triaged on real exposure rather than presence alone.

Is CVE-2026-42420 actively exploited in the wild?

No public exploit code has been indexed for CVE-2026-42420 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2026-42420?

CVE-2026-42420 has an EPSS (Exploit Prediction Scoring System) score of 0.3%, placing it in the 23th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2026-42420?

CVE-2026-42420 is classified as CWE-770 (CWE-770). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2026-42420 published, and has it been updated?

CVE-2026-42420 was published on April 28, 2026 and was last updated on August 17, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

📦 npm

Not in CISA KEV

CVE-2026-42420 — openclaw

Fix: openclaw/openclaw@d7c3210

CVE-2026-42420 is a CWE-770 vulnerability in openclaw. A fix is available for openclaw — see the affected versions and patch details below.

OpenClaw < 2026.4.8 - Improper Base64 Decoding Size Validation

Also known asGHSA-ccx3-fw7q-rr2r

Published

Apr 28, 2026

Updated

Aug 17, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Exploitation data as of Sep 21, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗

0.3%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs23th percentile — riskier than 23% of all scored CVEsHighest risk

EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.

Real-World Exposure

1 pkg 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.

133other npm packages depend on this — each one inherits the vulnerability until it's patched upstream

openclawnpm

2.7Mdownloads / week

Description

Impact

Multiple Code Paths Missing Base64 Pre-Allocation Size Checks.

Several base64 decode paths could allocate before enforcing decoded-size limits.

OpenClaw is a user-controlled local assistant. This advisory is scoped to the OpenClaw trust model and does not assume a multi-tenant service boundary.

Affected Packages / Versions

Package: openclaw (npm)
Affected versions: <=v2026.4.2
Patched versions: 2026.4.8

Fix

The issue was fixed on main and is available in the patched npm version listed above. The verified fixed tree is commit d7c3210cd6f5fdfdc1beff4c9541673e814354d5.

Verification

The fix was re-checked against main before publication, including targeted regression tests for the affected security boundary.

Credits

Thanks @zsxsoft and @KeenSecurityLab for reporting.

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
📦npm	`openclaw`	all versions	2026.4.8`npm install openclaw@2026.4.8`

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for openclaw, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update openclaw to 2026.4.8 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-42420 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2026-42420 can be triaged on real exposure rather than presence alone.

Tailored to CVE-2026-42420. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

## Impact Multiple Code Paths Missing Base64 Pre-Allocation Size Checks. Several base64 decode paths could allocate before enforcing decoded-size limits. OpenClaw is a user-controlled local assistant. This advisory is scoped to the OpenClaw trust model and does not assume a multi-tenant service boundary. ## Affected Packages / Versions - Package: `openclaw` (npm) - Affected versions: `<=v2026.4.2` - Patched versions: `2026.4.8` ## Fix The issue was fixed on `main` and is available in the patched npm version listed above. The verified fixed tree is commit `d7c3210cd6f5fdfdc1beff4c9541673

O3 Security · Impact-Aware SCA

Is CVE-2026-42420 in your dependencies?

O3 Security finds CVE-2026-42420 across npm dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.

Scan my dependencies How O3 SCA works