{"id":"CVE-2026-114655","kind":"vulnerability","aliases":["CVE-2026-114655"],"related":[],"title":"libmongocrypt: unvalidated key vault values let attackers alter signed KMS requests","description":"libmongocrypt builds requests to external key management services (AWS, Azure and GCP) by inserting values from key vault documents, KMS provider configuration and KMS responses into request lines, headers and signed request bodies without validating or encoding them for each context. A user with write access to the key vault collection can alter the structure of these requests, including adding members to request bodies and token claims that the library then signs with the application's credentials. This may result in key management operations being performed with parameters the application did not intend.","summary":"libmongocrypt builds requests to AWS, Azure and GCP key management services by inserting key vault and KMS response values into request lines, headers and signed bodies without encoding them. A user with write access to the key vault collection can change request structure, so the application's credentials sign key operations it did not intend.","severity":"medium","cvss":6.0,"epss":0.00267,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["aws-kms","azure-kms","client-side-encryption","gcp-kms","libmongocrypt","mongodb","package"],"not_affected_if":["local-kms-provider","no-untrusted-key-vault-writes"],"how_to_check":"- unknown","fix":"- unknown","status":"open","published_at":"2026-10-22T19:17:40+00:00","first_seen_at":"2026-10-23T21:57:31+00:00","triaged_at":"2026-10-25T04:05:23+00:00","updated_at":"2026-10-25T04:05:23+00:00","category":"package","confidence":0.5,"triage":{"at":"2026-10-25T04:05:23Z","model":"claude-haiku-5-5","output":{"fix":"- unknown","reach":"network","title":"libmongocrypt: unvalidated key vault values let attackers alter signed KMS requests","impact":"medium","summary":"libmongocrypt builds requests to AWS, Azure and GCP key management services by inserting key vault and KMS response values into request lines, headers and signed bodies without encoding them. A user with write access to the key vault collection can change request structure, so the application's credentials sign key operations it did not intend.","category":"package","nicknames":[],"who_cares":["mongodb","libmongocrypt","client-side-encryption","aws-kms","azure-kms","gcp-kms"],"confidence":0.5,"needs_auth":"yes","worst_case":"Attacker alters KMS requests signed with application credentials","analyst_note":"Find the affected and fixed libmongocrypt versions and the patched release notes at the NVD entry (https://nvd.nist.gov/vuln/detail/CVE-2026-114655) and the MongoDB advisory.","how_to_check":"- unknown","needs_analyst":true,"not_affected_if":["local-kms-provider","no-untrusted-key-vault-writes"],"who_is_affected":"Applications that use libmongocrypt for client-side field-level encryption or queryable encryption with an external KMS (AWS, Azure or GCP) and where untrusted parties can write to the key vault collection. The sources do not name affected libmongocrypt versions. Deployments using a local KMS provider or without write access to the key vault collection are unlikely to be exposed.","user_interaction":"no","needs_special_setup":"yes","severity_if_unknown":"medium"},"cost_usd":0.000622,"input_tokens":3410,"output_tokens":561,"severity_before":"medium"},"analyst_status":null,"analyst_note":null,"search":"'-114655':14A,17A '-2026':13A,16A 'access':67B,134C 'add':148C 'alter':8A,141C 'applic':79B,163C,178C 'attack':7A 'aw':19B,38B,97C 'aws-km':18B 'azur':22B,39B,98C 'azure-km':21B 'bodi':59B,121C,152C 'build':35B,90C 'chang':74B 'claim':155C 'client':25B 'client-side-encrypt':24B 'collect':72B,139C 'configur':110C 'context':129C 'credenti':81B,165C 'cve':12A,15A 'document':107C 'encod':61B,125C 'encrypt':27B 'extern':93C 'gcp':29B,41B,100C 'gcp-kms':28B 'header':56B,117C 'includ':147C 'insert':46B,102C 'intend':88B,181C 'key':3A,42B,47B,70B,83B,94C,105C,137C,170C 'kms':10A,20B,23B,30B,50B,108C,112C 'let':6A 'libmongocrypt':1A,31B,34B,89C 'librari':158C 'line':55B,116C 'manag':43B,95C,171C 'may':167C 'member':149C 'mongodb':32B 'oper':84B,172C 'packag':33B 'paramet':176C 'perform':174C 'provid':109C 'request':11A,36B,54B,75B,91C,115C,120C,146C,151C 'respons':51B,113C 'result':168C 'servic':44B,96C 'side':26B 'sign':9A,58B,82B,119C,160C 'structur':76B,143C 'token':154C 'unvalid':2A 'user':64B,131C 'valid':123C 'valu':5A,52B,103C 'vault':4A,48B,71B,106C,138C 'without':60B,122C 'write':66B,133C","nicknames":[],"mitigations":[],"who_affected":"Applications that use libmongocrypt for client-side field-level encryption or queryable encryption with an external KMS (AWS, Azure or GCP) and where untrusted parties can write to the key vault collection. The sources do not name affected libmongocrypt versions. Deployments using a local KMS provider or without write access to the key vault collection are unlikely to be exposed.","tier":"C","verified":{},"analyst_revisit_at":null,"first_public_at":"2026-10-22T19:17:40+00:00","kev":null,"cvss_vector":"CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X","cvss_by":"cna@mongodb.com","poc_count":0,"sources":[{"source":"nvd","external_id":"CVE-2026-114655","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-114655","severity":null,"published_at":"2026-10-22T19:17:40+00:00","modified_at":"2026-10-23T19:45:03+00:00","first_seen_at":"2026-10-23T21:57:31+00:00","fetched_at":"2026-10-23T22:29:02+00:00","note":null},{"source":"epss","external_id":"CVE-2026-114655","url":"https://api.first.org/data/v1/epss?cve=CVE-2026-114655","severity":null,"published_at":null,"modified_at":null,"first_seen_at":"2026-10-24T07:15:51+00:00","fetched_at":"2026-10-24T07:15:51+00:00","note":null}],"documents":[],"notice":"Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai"}