{"id":"CVE-2026-27576","aliases":["GHSA-cxpw-2g23-2vgw"],"url":"https://o3.security/vulnerability/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.","published":"2026-02-21T10:00:12.193Z","modified":"2026-08-12T03:51:16.995169760Z","cvss":null,"epss":null,"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"npm","name":"openclaw","fixedVersion":"2026.2.19"}],"fix":{"url":"https://github.com/openclaw/openclaw/commit/63e39d7f57ac4ad4a5e38d17e7394ae7c4dd0b9c","label":"openclaw/openclaw@63e39d7"},"references":[{"type":"WEB","url":"https://github.com/openclaw/openclaw/releases/tag/v2026.2.19"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/27xxx/CVE-2026-27576.json"},{"type":"ADVISORY","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":"FIX","url":"https://github.com/openclaw/openclaw/commit/63e39d7f57ac4ad4a5e38d17e7394ae7c4dd0b9c"},{"type":"FIX","url":"https://github.com/openclaw/openclaw/commit/8ae2d5110f6ceadef73822aa3db194fb60d2ba68"},{"type":"FIX","url":"https://github.com/openclaw/openclaw/commit/ebcf19746f5c500a41817e03abecadea8655654a"},{"type":"PACKAGE","url":"https://github.com/openclaw/openclaw"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-12T03:51:16.995169760Z"}}