CVE-2026-27576: OpenClaw ACP Prompt-size Checks Missing Vulnerability

MODERATE
Advisory Identifier: GHSA-cxpw-2g23-2vgw
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CWE-400
Published
Advisory Summary

CVE-2026-27576 is a MODERATE acp prompt-size checks missing vulnerability (CWE-400: Uncontrolled Resource Consumption) affecting OpenClaw libraries in the npm ecosystem. The issue involves acp prompt-size checks missing in local stdio bridge could reduce responsiveness with very large inputs. Remediation is available by upgrading affected packages to version 2026.2.19.

CVE-2026-27576 at a Glance

CVE Identifier CVE-2026-27576
GHSA Identifier GHSA-cxpw-2g23-2vgw
Severity MODERATE
CVSS v3.1 Base Score N/A
CWE Classification CWE-400: Uncontrolled Resource Consumption
Affected Product OpenClaw
Package Ecosystem npm
Published Date
Last Updated

How to Fix CVE-2026-27576

To remediate this vulnerability, upgrade all affected OpenClaw dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

openclaw fixed: 2026.2.19 
npm install openclaw@2026.2.19
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

npm ls openclaw

How to Check if You Are Affected

To determine whether your Node.js application is affected by CVE-2026-27576, inspect your project dependencies using npm:

npm ls openclaw

Analyze the terminal output to locate any version of OpenClaw in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 2026.2.19), your application is affected.

Note: The npm ls openclaw command inspects dependencies declared in your package.json and lockfile; it does not perform automated runtime dynamic scanning.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-400: Uncontrolled Resource Consumption, where the product does not properly control the allocation and maintenance of a limited resource. In OpenClaw, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

## Vulnerability The ACP bridge accepted very large prompt text blocks and could assemble oversized prompt payloads before forwarding them to `chat.send`. Because ACP runs over local stdio, this mainly affects local ACP clients (for example IDE integrations) that send unusually large inputs. ## Affected Packages / Versions - Package: `openclaw` (npm) - Affected versions: `<= 2026.2.17` - Patched version: `2026.2.18` (planned next release) ## Impact - Local ACP sessions may become less responsive when very large prompts are submitted - Larger-than-expected model usage/cost when oversized text is forwarded - No privilege escalation and no direct remote attack path in the default ACP model ## Affected Components - `src/acp/event-mapper.ts` - `src/acp/translator.ts` ## Remediation - Enforce a 2 MiB prompt-text limit before concatenation - Count inter-block newline separator bytes during pre-concatenation size checks - Keep final outbound message-size validation before `chat.send` - Avoid stale active-run session state when oversized prompts are rejected - Add regression tests for oversize rejection and active-run cleanup ## Fix Commit(s) - `732e53151e8fbdfc0501182ddb0e900878bdc1e3` - `ebcf19746f5c500a41817e03abecadea8655654a` - `63e39d7f57ac4ad4a5e38d17e7394ae7c4dd0b9c` Thanks @aether-ai-agent for reporting.

CVE-2026-27576 Affected OpenClaw Versions

1 component(s)
Fixed Versions:
2026.2.19
Product / Package Ecosystem Affected Versions Fixed Version
openclaw
npm/openclaw
npm
< 2026.2.19
2026.2.19

References

GitHub Advisory / Wiki ADVISORY
https://github.com/openclaw/openclaw/security/advisories/GHSA-cxpw-2g23-2vgw
NVD — CVE-2026-27576 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-27576
Security Fix Commit FIX COMMIT
https://github.com/openclaw/openclaw/commit/63e39d7f57ac4ad4a5e38d17e7394ae7c4dd0b9c
Security Fix Commit FIX COMMIT
https://github.com/openclaw/openclaw/commit/8ae2d5110f6ceadef73822aa3db194fb60d2ba68
Security Fix Commit FIX COMMIT
https://github.com/openclaw/openclaw/commit/ebcf19746f5c500a41817e03abecadea8655654a
OpenClaw Source Repository REPOSITORY
https://github.com/openclaw/openclaw
OpenClaw Release RELEASE
https://github.com/openclaw/openclaw/releases/tag/v2026.2.19

Frequently Asked Questions

What is CVE-2026-27576?
CVE-2026-27576 is a security vulnerability in OpenClaw involving ACP prompt-size checks missing in local stdio bridge could reduce responsiveness with very large inputs under CWE-400: Uncontrolled Resource Consumption.
Which OpenClaw versions are affected?
Affected versions include releases prior to 2026.2.19 across affected packages: openclaw.
What version fixes CVE-2026-27576?
Upgrading to 2026.2.19 (or the latest patched release for your respective branch) resolves the vulnerability.
Is openclaw affected?
Yes, openclaw is affected in releases prior to 2026.2.19. Upgrade your dependency to 2026.2.19 or later.
What CWE is associated with CVE-2026-27576?
CVE-2026-27576 is classified under CWE-400: Uncontrolled Resource Consumption (The product does not properly control the allocation and maintenance of a limited resource.).
How can I check npm dependencies for CVE-2026-27576?
Run the dependency tree command: 'npm ls openclaw'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-cxpw-2g23-2vgw",
  "modified" : "2026-02-23T22:30:08Z",
  "published" : "2026-02-20T21:52:44Z",
  "aliases" : [ "CVE-2026-27576" ],
  "summary" : "OpenClaw: ACP prompt-size checks missing in local stdio bridge could reduce responsiveness with very large inputs",
  "details" : "## Vulnerability\n\nThe ACP bridge accepted very large prompt text blocks and could assemble oversized prompt payloads before forwarding them to `chat.send`.\n\nBecause ACP runs over local stdio, this mainly affects local ACP clients (for example IDE integrations) that send unusually large inputs.\n\n## Affected Packages / Versions\n\n- Package: `openclaw` (npm)\n- Affected versions: `<= 2026.2.17`\n- Patched version: `2026.2.18` (planned next release)\n\n## Impact\n\n- Local ACP sessions may become less responsive when very large prompts are submitted\n- Larger-than-expected model usage/cost when oversized text is forwarded\n- No privilege escalation and no direct remote attack path in the default ACP model\n\n## Affected Components\n\n- `src/acp/event-mapper.ts`\n- `src/acp/translator.ts`\n\n## Remediation\n\n- Enforce a 2 MiB prompt-text limit before concatenation\n- Count inter-block newline separator bytes during pre-concatenation size checks\n- Keep final outbound message-size validation before `chat.send`\n- Avoid stale active-run session state when oversized prompts are rejected\n- Add regression tests for oversize rejection and active-run cleanup\n\n## Fix Commit(s)\n\n- `732e53151e8fbdfc0501182ddb0e900878bdc1e3`\n- `ebcf19746f5c500a41817e03abecadea8655654a`\n- `63e39d7f57ac4ad4a5e38d17e7394ae7c4dd0b9c`\n\nThanks @aether-ai-agent for reporting.",
  "severity" : [ {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "npm",
      "name" : "openclaw"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "2026.2.19"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 2026.2.17"
    }
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/openclaw/openclaw/security/advisories/GHSA-cxpw-2g23-2vgw"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-27576"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/openclaw/openclaw/commit/63e39d7f57ac4ad4a5e38d17e7394ae7c4dd0b9c"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/openclaw/openclaw/commit/8ae2d5110f6ceadef73822aa3db194fb60d2ba68"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/openclaw/openclaw/commit/ebcf19746f5c500a41817e03abecadea8655654a"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/openclaw/openclaw"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/openclaw/openclaw/releases/tag/v2026.2.19"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-400" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-02-20T21:52:44Z",
    "nvd_published_at" : "2026-02-21T10:16:13Z"
  }
}