{"id":"GHSA-4wq9-grf3-qg2p","kind":"vulnerability","aliases":["GHSA-4wq9-grf3-qg2p"],"related":[],"title":"CVE-2026-125271 - AWS API MCP Server Security Policy Bypass via Incorrect Operation Name Normalization","description":"CVE-2026-125271 - AWS API MCP Server Security Policy Bypass via Incorrect Operation Name Normalization\n\n### CVE-2026-125271 - AWS API MCP Server Security Policy Bypass via Incorrect Operation Name Normalization\n\nBulletin ID: 2026-176-AWS Scope: AWS Content Type: Important (requires attention) Publication Date: 11/10/2026 08:30 AM PST\n\n Description:\n\nAWS API MCP Server is an open source Model Context Protocol (MCP) server that customers run to let AI assistants manage their AWS accounts through AWS API calls.\n\nWe identified CVE-2026-125271, an issue in the custom security policy enforcement of AWS API MCP Server versions between 0.2.13 and 1.5.0. The server normalized operation names incorrectly before comparing them to the operator's security policy, so operations whose names contain consecutive capital letters never matched a correctly written denyList or elicitList entry. This might allow an actor to execute AWS API operations that the operator's security policy was configured to deny or require elicitation for.\n\nImpacted versions: >= 0.2.13 AND < 1.5.1\n\nResolution:\n\nThis issue has been addressed in awslabs.aws-api-mcp-server version 1.5.1. We recommend upgrading to the latest version and ensuring any forked or derivative code is patched to incorporate the new fixes.\n\nWorkarounds:\n\nThere is no workaround other than upgrading.\n\nReferences:\n\n- CVE-2026-125271\n- GHSA-4wq9-grf3-qg2p\n\nAcknowledgement:\n\nWe would like to thank Syed Anas Mohiuddin for collaborating on this issue through the coordinated vulnerability disclosure process.\n\n Please email aws-security@amazon.com with any s ecurity questions or concerns.","summary":"The AWS API MCP Server normalized operation names incorrectly, so operations with consecutive capital letters never matched the operator's denyList or elicitList entries. An actor could run AWS API operations that the operator's security policy was meant to deny or require confirmation for.","severity":"unknown","cvss":null,"epss":null,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["ai-tooling","aws","aws-api-mcp-server","lab-disclosure","mcp"],"not_affected_if":["no-custom-security-policy","version-1.5.1-or-later"],"how_to_check":"- Check the installed `awslabs.aws-api-mcp-server` version; affected versions are `>= 0.2.13` and `< 1.5.1`.\n- Look for a custom security policy with `denyList` or `elicitList` entries on the server.","fix":"- `awslabs.aws-api-mcp-server` upgrade to `1.5.1`\n- Forked or derivative code: patch to include the new fixes (per AWS)","status":"open","published_at":null,"first_seen_at":"2026-11-10T17:00:47+00:00","triaged_at":"2026-11-10T17:02:37+00:00","updated_at":"2026-11-10T17:02:37+00:00","category":"ai-tooling","confidence":0.7,"triage":{"at":"2026-11-10T17:02:37Z","model":"claude-haiku-5-5","output":{"fix":"- `awslabs.aws-api-mcp-server` upgrade to `1.5.1`\n- Forked or derivative code: patch to include the new fixes (per AWS)","reach":"unknown","title":"AWS API MCP Server: operation-name bypass skips denyList and elicitation policies","impact":"high","summary":"The AWS API MCP Server normalized operation names incorrectly, so operations with consecutive capital letters never matched the operator's denyList or elicitList entries. An actor could run AWS API operations that the operator's security policy was meant to deny or require confirmation for.","audience":"businesses","category":"ai-tooling","nicknames":[],"who_cares":["aws","mcp","aws-api-mcp-server"],"confidence":0.7,"fix_status":"available","needs_auth":"unknown","worst_case":"AWS operations denied by policy run without confirmation","analyst_note":"","how_to_check":"- Check the installed `awslabs.aws-api-mcp-server` version; affected versions are `>= 0.2.13` and `< 1.5.1`.\n- Look for a custom security policy with `denyList` or `elicitList` entries on the server.","plain_action":"","product_name":"","needs_analyst":false,"not_affected_if":["version-1.5.1-or-later","no-custom-security-policy"],"who_is_affected":"Teams that run the AWS API MCP Server with a custom security policy (denyList or elicitList) that lets AI assistants call AWS APIs. Forked or derivative copies of the code are also affected until patched. Servers on `1.5.1` or later, or without a custom policy, are not affected by this bypass.","user_interaction":"unknown","product_ecosystem":"","needs_special_setup":"yes","severity_if_unknown":"unknown"},"cost_usd":0.000822,"input_tokens":5141,"output_tokens":615,"severity_before":"unknown"},"analyst_status":null,"analyst_note":null,"search":"'-125271':3A,85C,100C,165C,291C '-176':116C '-2026':2A,84C,99C,164C,290C '0.2.13':181C,242C '08':128C '1.5.0':183C '1.5.1':244C,258C '11/10/2026':127C '2026':115C '30':129C '4wq9':18A,23A,294C 'account':156C 'acknowledg':297C 'actor':64B,220C 'address':250C 'ai':27B,151C 'ai-tool':26B 'allow':218C 'ana':304C 'api':5A,32B,41B,68B,87C,102C,134C,159C,176C,224C,254C 'api-mcp-serv':253C 'assist':152C 'attent':124C 'aw':4A,29B,31B,40B,67B,86C,101C,117C,119C,133C,155C,158C,175C,223C 'aws-api-mcp-serv':30B 'aws-security@amazon.com':319C 'awslabs.aws':252C 'bulletin':113C 'bypass':10A,92C,107C 'call':160C 'capit':52B,205C 'code':272C 'collabor':307C 'compar':191C 'concern':326C 'configur':233C 'confirm':82B 'consecut':51B,204C 'contain':203C 'content':120C 'context':142C 'coordin':313C 'correct':210C 'could':65B 'custom':147C,170C 'cve':1A,83C,98C,163C,289C 'date':126C 'deni':79B,235C 'denylist':59B,212C 'deriv':271C 'descript':132C 'disclosur':37B,315C 'ecur':323C 'elicit':238C 'elicitlist':61B,214C 'email':318C 'enforc':173C 'ensur':267C 'entri':62B,215C 'execut':222C 'fix':279C 'fork':269C 'ghsa':17A,22A,293C 'ghsa-4wq9-grf3-qg2p':16A,21A,292C 'grf3':19A,24A,295C 'id':114C 'identifi':162C 'impact':240C 'import':122C 'incorpor':276C 'incorrect':12A,47B,94C,109C,189C 'issu':167C,247C,310C 'lab':36B 'lab-disclosur':35B 'latest':264C 'let':150C 'letter':53B,206C 'like':300C 'manag':153C 'match':55B,208C 'mcp':6A,33B,38B,42B,88C,103C,135C,144C,177C,255C 'meant':77B 'might':217C 'model':141C 'mohiuddin':305C 'name':14A,46B,96C,111C,188C,202C 'never':54B,207C 'new':278C 'normal':15A,44B,97C,112C,186C 'open':139C 'oper':13A,45B,49B,57B,69B,72B,95C,110C,187C,195C,200C,225C,228C 'patch':274C 'pleas':317C 'polici':9A,75B,91C,106C,172C,198C,231C 'process':316C 'protocol':143C 'pst':131C 'public':125C 'qg2p':20A,25A,296C 'question':324C 'recommend':260C 'refer':288C 'requir':81B,123C,237C 'resolut':245C 'run':66B,148C 'scope':118C 'secur':8A,74B,90C,105C,171C,197C,230C 'server':7A,34B,43B,89C,104C,136C,145C,178C,185C,256C 'sourc':140C 'sy':303C 'thank':302C 'tool':28B 'type':121C 'upgrad':261C,287C 'version':179C,241C,257C,265C 'via':11A,93C,108C 'vulner':314C 'whose':201C 'workaround':280C,284C 'would':299C 'written':211C","nicknames":[],"mitigations":[],"who_affected":"Teams that run the AWS API MCP Server with a custom security policy (denyList or elicitList) that lets AI assistants call AWS APIs. Forked or derivative copies of the code are also affected until patched. Servers on `1.5.1` or later, or without a custom policy, are not affected by this bypass.","tier":"B","verified":{},"analyst_revisit_at":null,"fix_status":"available","audience":"businesses","plain_action":null,"pkeys":[],"ptokens":[],"labels":["aitooling","aws","awsapimcpserver","labdisclosure","mcp","unknown"],"campaign_type":null,"search_a":"'-125271':3A '-2026':2A '4wq9':18A,23A 'api':5A 'aw':4A 'bypass':10A 'cve':1A 'ghsa':17A,22A 'ghsa-4wq9-grf3-qg2p':16A,21A 'grf3':19A,24A 'incorrect':12A 'mcp':6A 'name':14A 'normal':15A 'oper':13A 'polici':9A 'qg2p':20A,25A 'secur':8A 'server':7A 'via':11A","search_b":"'actor':64B 'ai':27B 'ai-tool':26B 'api':32B,41B,68B 'aw':29B,31B,40B,67B 'aws-api-mcp-serv':30B 'capit':52B 'confirm':82B 'consecut':51B 'could':65B 'deni':79B 'denylist':59B 'disclosur':37B 'elicitlist':61B 'entri':62B 'incorrect':47B 'lab':36B 'lab-disclosur':35B 'letter':53B 'match':55B 'mcp':33B,38B,42B 'meant':77B 'name':46B 'never':54B 'normal':44B 'oper':45B,49B,57B,69B,72B 'polici':75B 'requir':81B 'run':66B 'secur':74B 'server':34B,43B 'tool':28B","search_c":"'-125271':85C,100C,165C,291C '-176':116C '-2026':84C,99C,164C,290C '0.2.13':181C,242C '08':128C '1.5.0':183C '1.5.1':244C,258C '11/10/2026':127C '2026':115C '30':129C '4wq9':294C 'account':156C 'acknowledg':297C 'actor':220C 'address':250C 'ai':151C 'allow':218C 'ana':304C 'api':87C,102C,134C,159C,176C,224C,254C 'api-mcp-serv':253C 'assist':152C 'attent':124C 'aw':86C,101C,117C,119C,133C,155C,158C,175C,223C 'aws-security@amazon.com':319C 'awslabs.aws':252C 'bulletin':113C 'bypass':92C,107C 'call':160C 'capit':205C 'code':272C 'collabor':307C 'compar':191C 'concern':326C 'configur':233C 'consecut':204C 'contain':203C 'content':120C 'context':142C 'coordin':313C 'correct':210C 'custom':147C,170C 'cve':83C,98C,163C,289C 'date':126C 'deni':235C 'denylist':212C 'deriv':271C 'descript':132C 'disclosur':315C 'ecur':323C 'elicit':238C 'elicitlist':214C 'email':318C 'enforc':173C 'ensur':267C 'entri':215C 'execut':222C 'fix':279C 'fork':269C 'ghsa':293C 'ghsa-4wq9-grf3-qg2p':292C 'grf3':295C 'id':114C 'identifi':162C 'impact':240C 'import':122C 'incorpor':276C 'incorrect':94C,109C,189C 'issu':167C,247C,310C 'latest':264C 'let':150C 'letter':206C 'like':300C 'manag':153C 'match':208C 'mcp':88C,103C,135C,144C,177C,255C 'might':217C 'model':141C 'mohiuddin':305C 'name':96C,111C,188C,202C 'never':207C 'new':278C 'normal':97C,112C,186C 'open':139C 'oper':95C,110C,187C,195C,200C,225C,228C 'patch':274C 'pleas':317C 'polici':91C,106C,172C,198C,231C 'process':316C 'protocol':143C 'pst':131C 'public':125C 'qg2p':296C 'question':324C 'recommend':260C 'refer':288C 'requir':123C,237C 'resolut':245C 'run':148C 'scope':118C 'secur':90C,105C,171C,197C,230C 'server':89C,104C,136C,145C,178C,185C,256C 'sourc':140C 'sy':303C 'thank':302C 'type':121C 'upgrad':261C,287C 'version':179C,241C,257C,265C 'via':93C,108C 'vulner':314C 'whose':201C 'workaround':280C,284C 'would':299C 'written':211C","cause_entry":null,"cause_path":null,"disclosures_checked_at":null,"first_public_at":null,"kev":null,"cvss_vector":null,"cvss_by":null,"poc_count":0,"sources":[{"source":"lab","external_id":"https://aws.amazon.com/security/security-bulletins/2026-176-aws/#GHSA-4wq9-grf3-qg2p","url":"https://aws.amazon.com/security/security-bulletins/2026-176-aws/","severity":null,"published_at":null,"modified_at":null,"first_seen_at":"2026-11-10T17:00:47+00:00","fetched_at":"2026-11-10T17:00:47+00:00","note":"AWS: CVE-2026-125271 - AWS API MCP Server Security Policy Bypass via Incorrect Operation Name Normalization"}],"documents":[{"id":116444,"url":"https://aws.amazon.com/security/security-bulletins/2026-176-aws/","title":"AWS: CVE-2026-125271 - AWS API MCP Server Security Policy Bypass via Incorrect Operation Name Normalization","kind":"advisory","source":"lab","publisher":"research","text":"CVE-2026-125271 - AWS API MCP Server Security Policy Bypass via Incorrect Operation Name Normalization\n\n### CVE-2026-125271 - AWS API MCP Server Security Policy Bypass via Incorrect Operation Name Normalization\n\nBulletin ID: 2026-176-AWS Scope: AWS Content Type: Important (requires attention) Publication Date: 11/10/2026 08:30 AM PST\n\n Description:\n\nAWS API MCP Server is an open source Model Context Protocol (MCP) server that customers run to let AI assistants manage their AWS accounts through AWS API calls.\n\nWe identified CVE-2026-125271, an issue in the custom security policy enforcement of AWS API MCP Server versions between 0.2.13 and 1.5.0. The server normalized operation names incorrectly before comparing them to the operator's security policy, so operations whose names contain consecutive capital letters never matched a correctly written denyList or elicitList entry. This might allow an actor to execute AWS API operations that the operator's security policy was configured to deny or require elicitation for.\n\nImpacted versions: >= 0.2.13 AND < 1.5.1\n\nResolution:\n\nThis issue has been addressed in awslabs.aws-api-mcp-server version 1.5.1. We recommend upgrading to the latest version and ensuring any forked or derivative code is patched to incorporate the new fixes.\n\nWorkarounds:\n\nThere is no workaround other than upgrading.\n\nReferences:\n\n- CVE-2026-125271\n- GHSA-4wq9-grf3-qg2p\n\nAcknowledgement:\n\nWe would like to thank Syed Anas Mohiuddin for collaborating on this issue through the coordinated vulnerability disclosure process.\n\n Please email aws-security@amazon.com with any s ecurity questions or concerns.","published_at":null,"relation":"advisory","confidence":null,"note":null}],"disclosures":[],"exploit_sources":[],"notice":"Free to read, with fair use of about 60 pages a minute. For higher limits or API access: sales@infrastack.ai"}