{"id":"CVE-2026-120813","kind":"vulnerability","aliases":["CVE-2026-120813"],"related":[],"title":"MongoDB Server: duplicate keys in a CSFLE schema can leave encrypted fields in plaintext","description":"An issue in MongoDB Server's client-side field-level encryption (CSFLE) schema processing component allows encryption metadata to be silently dropped during schema parsing under certain conditions. A party who can deliver a specially crafted schema to a user's CSFLE client may cause sensitive data intended for encryption to be stored in plaintext, bypassing confidentiality protections. Exploitation requires the ability to deliver the malicious schema to the user's client, such as through a man-in-the-middle position or an untrusted server.","summary":"A flaw in how MongoDB Server's client-side field-level encryption (CSFLE) parses schemas can silently drop encryption metadata. An attacker who can deliver a crafted schema to a client can cause data meant for encryption to be stored in plaintext.","severity":"high","cvss":8.2,"epss":null,"exploited":false,"exploited_at":null,"products":[{"name":"MongoDB Server","fixed":["7.0.48","8.0.37","8.3.16","9.0.7"],"affected":">= 7.0.0, < 7.0.48; >= 8.0.0, < 8.0.37; >= 8.3.0, < 8.3.16; >= 9.0.0, < 9.0.7","ecosystem":"vendor"}],"ecosystems":[],"tags":["csfle","drivers","encryption","mongodb","runtime","self-hosted"],"not_affected_if":["local-schema-only","no-csfle"],"how_to_check":"Run mongod --version (or db.version()) and compare to the fixed releases: 7.0.48, 8.0.37, 8.3.16, 9.0.7. Affected: 7.0.0-7.0.47, 8.0.0-8.0.36, 8.3.0-8.3.15, 9.0.0-9.0.6. Then check whether your clients use CSFLE (autoEncryption / schemaMap, or a server-supplied jsonSchema) and whether any schema could contain duplicate property keys or identical patternProperties regexes; a schema you define locally and control is not attacker-supplied.","fix":"Upgrade MongoDB Server to 9.0.7, 8.3.16, 8.0.37 or 7.0.48 (or later on your line). The fix rejects CSFLE schemas with duplicate properties/patternProperties keys (FailedToParse).","status":"open","published_at":"2026-11-10T20:18:51+00:00","first_seen_at":"2026-11-10T20:46:02+00:00","triaged_at":"2026-11-10T20:47:35+00:00","updated_at":"2026-11-10T21:02:08+00:00","category":"runtime","confidence":0.8,"triage":{"at":"2026-11-10T20:47:35Z","model":"claude-haiku-5-5","output":{"fix":"unknown","reach":"network","title":"MongoDB Server: crafted CSFLE schema can leave sensitive data unencrypted","impact":"high","summary":"A flaw in how MongoDB Server's client-side field-level encryption (CSFLE) parses schemas can silently drop encryption metadata. An attacker who can deliver a crafted schema to a client can cause data meant for encryption to be stored in plaintext.","audience":"businesses","category":"runtime","nicknames":[],"who_cares":["mongodb","csfle","self-hosted","drivers"],"confidence":0.6,"fix_status":"unknown","needs_auth":"no","worst_case":"sensitive fields stored in plaintext, bypassing encryption","analyst_note":"Check the NVD entry and MongoDB's security advisory for affected versions and fixed releases; the sources here list no product ranges.","how_to_check":"- Check whether applications use client-side field-level encryption (CSFLE) with a schema supplied by a server or other party, using `mongod --version` on the server and reviewing the `autoEncryption` / `schemaMap` settings in client code.\n- unknown for affected version ranges, since the sources do not list them.","plain_action":"","product_name":"","needs_analyst":true,"not_affected_if":["local-schema-only","no-csfle"],"who_is_affected":"Exposure requires a CSFLE client that accepts a schema from an untrusted source, such as a server the client does not fully control or a position where traffic can be intercepted. Applications that hard-code their encryption schema locally are less exposed. The sources do not list affected versions.","user_interaction":"no","product_ecosystem":"","needs_special_setup":"yes","severity_if_unknown":"high"},"cost_usd":0.000753,"input_tokens":4620,"output_tokens":581,"severity_before":"high"},"analyst_status":"done","analyst_note":"Check the NVD entry and MongoDB's security advisory for affected versions and fixed releases; the sources here list no product ranges.","search":"'-120813':17A,20A '-2026':16A,19A 'abil':138C 'allow':92C 'attack':54B 'bypass':132C 'caus':65B,121C 'certain':103C 'client':39B,63B,82C,119C,148C 'client-sid':38B,81C 'compon':91C 'condit':104C 'confidenti':133C 'craft':59B,112C 'csfle':7A,23B,45B,88C,118C 'cve':15A,18A 'data':66B,123C 'deliv':57B,109C,140C 'driver':24B 'drop':50B,98C 'duplic':3A 'encrypt':11A,25B,44B,51B,69B,87C,93C,126C 'exploit':135C 'field':12A,42B,85C 'field-level':41B,84C 'flaw':32B 'host':30B 'intend':124C 'issu':76C 'key':4A 'leav':10A 'level':43B,86C 'malici':142C 'man':154C 'man-in-the-middl':153C 'may':120C 'meant':67B 'metadata':52B,94C 'middl':157C 'mongodb':1A,21A,26B,35B,78C 'pars':46B,101C 'parti':106C 'plaintext':14A,74B,131C 'posit':158C 'process':90C 'protect':134C 'requir':136C 'runtim':27B 'schema':8A,47B,60B,89C,100C,113C,143C 'self':29B 'self-host':28B 'sensit':122C 'server':2A,22A,36B,79C,162C 'side':40B,83C 'silent':49B,97C 'special':111C 'store':72B,129C 'untrust':161C 'user':116C,146C","nicknames":[],"mitigations":[],"who_affected":"Teams running MongoDB Server 7.0, 8.0, 8.3 or 9.0 below the fixed releases whose clients use client-side field-level encryption with a schema that someone else can influence (a man-in-the-middle position or an untrusted server). With duplicate keys, one entry's encryption settings overwrite another's, so a field you expected encrypted is stored in plaintext. Teams without CSFLE, or with a locally fixed schema nobody else can alter, can skip it.","tier":"B","verified":{"fix":{"at":"2026-11-10T21:02:08Z","by":"analyst","doc":"https://jira.mongodb.org/browse/SERVER-132517","run_id":2739}},"analyst_revisit_at":null,"fix_status":"available","audience":"businesses","plain_action":null,"pkeys":["mongodbserver","server"],"ptokens":["mongodb","server"],"labels":["csfle","drivers","encryption","high","mongodb","runtime","selfhosted"],"campaign_type":null,"search_a":"'-120813':17A,20A '-2026':16A,19A 'csfle':7A 'cve':15A,18A 'duplic':3A 'encrypt':11A 'field':12A 'key':4A 'leav':10A 'mongodb':1A,21A 'plaintext':14A 'schema':8A 'server':2A,22A","search_b":"'attack':54B 'caus':65B 'client':39B,63B 'client-sid':38B 'craft':59B 'csfle':23B,45B 'data':66B 'deliv':57B 'driver':24B 'drop':50B 'encrypt':25B,44B,51B,69B 'field':42B 'field-level':41B 'flaw':32B 'host':30B 'level':43B 'meant':67B 'metadata':52B 'mongodb':26B,35B 'pars':46B 'plaintext':74B 'runtim':27B 'schema':47B,60B 'self':29B 'self-host':28B 'server':36B 'side':40B 'silent':49B 'store':72B","search_c":"'abil':138C 'allow':92C 'bypass':132C 'caus':121C 'certain':103C 'client':82C,119C,148C 'client-sid':81C 'compon':91C 'condit':104C 'confidenti':133C 'craft':112C 'csfle':88C,118C 'data':123C 'deliv':109C,140C 'drop':98C 'encrypt':87C,93C,126C 'exploit':135C 'field':85C 'field-level':84C 'intend':124C 'issu':76C 'level':86C 'malici':142C 'man':154C 'man-in-the-middl':153C 'may':120C 'metadata':94C 'middl':157C 'mongodb':78C 'pars':101C 'parti':106C 'plaintext':131C 'posit':158C 'process':90C 'protect':134C 'requir':136C 'schema':89C,100C,113C,143C 'sensit':122C 'server':79C,162C 'side':83C 'silent':97C 'special':111C 'store':129C 'untrust':161C 'user':116C,146C","cause_entry":null,"cause_path":null,"disclosures_checked_at":null,"first_public_at":"2026-11-10T20:18:51+00:00","kev":null,"cvss_vector":"CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:N/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-2026-120813","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-120813","severity":null,"published_at":"2026-11-10T20:18:51+00:00","modified_at":"2026-11-10T20:18:51+00:00","first_seen_at":"2026-11-10T20:46:02+00:00","fetched_at":"2026-11-10T20:46:02+00:00","note":null},{"source":"analyst","external_id":"CVE-2026-120813:2739","url":"https://jira.mongodb.org/browse/SERVER-132517","severity":null,"published_at":"2026-11-10T21:02:08+00:00","modified_at":"2026-11-10T21:02:08+00:00","first_seen_at":"2026-11-10T21:02:08+00:00","fetched_at":"2026-11-10T21:02:08+00:00","note":"Fix versions from MongoDB Jira SERVER-132517 (vendor); affected ranges from MongoDB CNA CVE record (via CIRCL mirror; NVD page returned nothing). No exploitation or PoC found; no social search done (low-profile B). Product ranges not marked verified; the CNA CPE status is 'guessed'. No code check: depends on schema provenance.","cites":["https://jira.mongodb.org/browse/SERVER-132517","https://cve.circl.lu/vuln/cve-2026-120813"]}],"documents":[{"id":118478,"url":"https://jira.mongodb.org/browse/SERVER-132517","title":"SERVER-132517: Reject duplicate keys in CSFLE encryption schema tree","kind":"advisory","source":"analyst","publisher":null,"text":null,"published_at":null,"relation":"advisory","confidence":null,"note":null},{"id":118479,"url":"https://cve.circl.lu/vuln/cve-2026-120813","title":"CVE-2026-120813 CVE record (MongoDB CNA) via Vulnerability-Lookup","kind":"other","source":"analyst","publisher":null,"text":null,"published_at":null,"relation":"describes","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"}