How severe is CVE-2026-28478?

No CVSS score has been assigned to CVE-2026-28478 yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by CVE-2026-28478?

CVE-2026-28478 affects the following packages: openclaw (npm), clawdbot (npm). Ecosystems affected: npm.

How do I fix CVE-2026-28478?

Update openclaw to 2026.2.13 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-28478 is resolved across your whole dependency graph.

How do I detect CVE-2026-28478 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-2026-28478 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-2026-28478?

O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2026-28478 can be triaged on real exposure rather than presence alone.

Is CVE-2026-28478 actively exploited in the wild?

No public exploit code has been indexed for CVE-2026-28478 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-2026-28478?

CVE-2026-28478 has an EPSS (Exploit Prediction Scoring System) score of 0.4%, placing it in the 37th 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-2026-28478?

CVE-2026-28478 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-2026-28478 published, and has it been updated?

CVE-2026-28478 was published on March 5, 2026 and was last updated on August 12, 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-2026-28478 — openclaw

Fix: openclaw/openclaw@3cbcba1

CVE-2026-28478 is a CWE-770 vulnerability in openclaw. A fix is available for openclaw — see the affected versions and patch details below.

OpenClaw < 2026.2.13 - Denial of Service via Unbounded Webhook Request Body Buffering

Also known asGHSA-q447-rj3r-2cgh

Published

Mar 5, 2026

Updated

Aug 12, 2026

Affected

2 pkgs

Patched

1 / 2

Exploits

None indexed

Exploitation data as of Sep 19, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
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 CVE-2026-28478.

EPSS Exploitation Probability

via FIRST.org ↗

0.4%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs37th percentile — riskier than 37% 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

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.

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

openclawnpm

3.0Mdownloads / week

clawdbotnpm

942downloads / week

Description

Summary

Multiple webhook handlers accepted and buffered request bodies without a strict unified byte/time limit. A remote unauthenticated attacker could send oversized payloads and cause memory pressure, degrading availability.

Details

Affected packages:

openclaw (npm): <2026.2.12
clawdbot (npm): <=2026.1.24-3

Root cause:

Webhook code paths buffered request payloads without consistent maxBytes + timeoutMs enforcement.
Some SDK-backed handlers parse request bodies internally and needed stream-level guards.

Attack shape:

Send very large JSON payloads or slow/incomplete uploads to webhook endpoints.
Observe elevated memory usage and request handler pressure.

Impact

Remote unauthenticated availability impact (DoS) via request body amplification/memory pressure.

Patch details (implemented)

Added shared bounded request-body helper in src/infra/http-body.ts.
Exported helper in src/plugin-sdk/index.ts for extension reuse.
Migrated webhook body readers to shared helper for:
- LINE
- Nextcloud Talk
- Google Chat
- Zalo
- BlueBubbles
- Nostr profile HTTP
- Voice-call
- Gateway hooks
Added stream guards for SDK handlers that parse request bodies internally:
- Slack
- Telegram
- Feishu
Added explicit Express JSON body limit handling for MS Teams webhook path.
Standardized failure responses:
- 413 Payload Too Large
- 408 Request Timeout

Tests

Added regression tests:
- src/infra/http-body.test.ts
- src/line/monitor.read-body.test.ts
- extensions/nextcloud-talk/src/monitor.read-body.test.ts
Focused webhook/security test suite passes for patched paths.

Remediation

Upgrade to the first release containing this patch.

Credits

Thanks @vincentkoc for reporting.

Affected Packages

2 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
📦npm	`openclaw`	all versions	2026.2.13`npm install openclaw@2026.2.13`
📦npm	`clawdbot`	all versions	No fix

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 2026.2.13 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-28478 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-2026-28478 can be triaged on real exposure rather than presence alone.

Tailored to CVE-2026-28478. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

### Summary Multiple webhook handlers accepted and buffered request bodies without a strict unified byte/time limit. A remote unauthenticated attacker could send oversized payloads and cause memory pressure, degrading availability. ### Details Affected packages: - `openclaw` (npm): `<2026.2.12` - `clawdbot` (npm): `<=2026.1.24-3` Root cause: - Webhook code paths buffered request payloads without consistent `maxBytes` + `timeoutMs` enforcement. - Some SDK-backed handlers parse request bodies internally and needed stream-level guards. Attack shape: - Send very large JSON payloads or slow/inco

O3 Security · Impact-Aware SCA

Is CVE-2026-28478 in your dependencies?

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