CVE-2026-27576

ACP session slowdown via unbounded prompt concatenation

Published Feb 21, 2026 · Updated Feb 21, 2026

Uncontrolled resource consumption in OpenClaw before 2026.2.19 allows local users to degrade ACP responsiveness with oversized prompts. The ACP bridge's extractTextFromPrompt path concatenates unbounded text blocks before chat.send, allocating the complete payload without a pre-concatenation byte limit. Reachability requires a local stdio ACP client, and documented consequences are session slowdown and excess model usage or cost without privilege escalation or a default remote path.

CVSS severity4.0
Medium
EPSS probability0.17%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Uncontrolled resource consumption in OpenClaw before 2026.2.19 allows local users to degrade ACP responsiveness with oversized prompts. The ACP bridge's extractTextFromPrompt path concatenates unbounded text blocks before chat.send, allocating the complete payload without a pre-concatenation byte limit. Reachability requires a local stdio ACP client, and documented consequences are session slowdown and excess model usage or cost without privilege escalation or a default remote path.

The record

CVE
CVE-2026-27576
Published
Feb 21, 2026
Updated
Feb 21, 2026
Vendor
OpenClaw Foundation
Product
OpenClaw
Classifications
CWE-400, CWE-20, T1499
Attack vector
local
Privileges
Unavailable

Timeline

How it unfolded

  1. Feb 21, 2026CVE publishedPublication date reported by the CVE source.
  2. Feb 21, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 2026.2.19

What conditions does exploitation require?

Attack vectorlocal
Required privilegesUnavailable in this record.

What is affected?

OpenClaw Foundation · OpenClawversion=< 2026.2.19

Published CVSS scores

4.8GitHub, Inc.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
4.0National Institute of Standards and TechnologyCVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
PrivilegesUnavailable
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-400Uncontrolled Resource Consumption
CWE-20Improper Input Validation
T1499Endpoint Denial of Service

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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