CVE-2026-27576
OpenClaw: ACP prompt-size checks missing in local stdio bridge could reduce responsiveness with very large inputs
Description
## 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.
How to fix CVE-2026-27576
To remediate CVE-2026-27576, upgrade the affected package to a fixed version below.
- —upgrade to 2026.2.19 or later
Is CVE-2026-27576 being exploited?
Low — EPSS is 0.0%, meaning exploitation activity has not been observed at scale.
Affected packages (1)
- from 0, < 2026.2.19
CVSS scores
| Source | Version | Severity | Vector |
|---|---|---|---|
| osv | CVSS 4.0 | — | 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 |