{"id":"CVE-2026-120684","kind":"vulnerability","aliases":["CVE-2026-120684"],"related":[],"title":"MongoDB C Driver: uninitialized memory can leak into GridFS stored files","description":"A memory-initialization flaw in the legacy GridFS file handling of the MongoDB C Driver can cause uninitialized process memory to be treated as valid file content and stored on the server. A database user holding ordinary write access to a shared storage area can arrange conditions under which an application later appends to such a file and writes that memory into records the same user is permitted to read, which may result in unintended disclosure of sensitive information from the application's process, including credentials.","summary":"The legacy GridFS file code in the MongoDB C Driver can store uninitialized process memory as file content. A database user with ordinary write access to shared storage may later read that memory, which can expose sensitive data from the application's process, including credentials.","severity":"medium","cvss":6.5,"epss":null,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["c-driver","gridfs","libmongoc","mongodb","package"],"not_affected_if":["no-c-driver","no-gridfs"],"how_to_check":null,"fix":null,"status":"open","published_at":"2026-11-03T19:18:00+00:00","first_seen_at":"2026-11-03T19:44:52+00:00","triaged_at":"2026-11-03T19:45:39+00:00","updated_at":"2026-11-03T19:45:39+00:00","category":"package","confidence":0.5,"triage":{"at":"2026-11-03T19:45:39Z","model":"claude-haiku-5-5","output":{"fix":"unknown","reach":"network","title":"MongoDB C Driver: uninitialized memory can leak into GridFS stored files","impact":"medium","summary":"The legacy GridFS file code in the MongoDB C Driver can store uninitialized process memory as file content. A database user with ordinary write access to shared storage may later read that memory, which can expose sensitive data from the application's process, including credentials.","audience":"developers","category":"package","nicknames":[],"who_cares":["mongodb","c-driver","gridfs","libmongoc"],"confidence":0.5,"fix_status":"unknown","needs_auth":"yes","worst_case":"Process memory including credentials readable by a low-privilege database user","analyst_note":"Find the affected and fixed libmongoc versions and whether the flaw applies to the default GridFS configuration, via the NVD entry https://nvd.nist.gov/vuln/detail/CVE-2026-120684 and the MongoDB advisory.","how_to_check":"- Find where the MongoDB C Driver (libmongoc) is used and check its version, for example `pkg-config --modversion libmongoc-1.0` or the version pinned in your build files.\n- Check whether the application uses legacy GridFS file append or write paths through the C driver.","plain_action":"","needs_analyst":true,"not_affected_if":["no-gridfs","no-c-driver"],"who_is_affected":"Applications built on the MongoDB C Driver that use legacy GridFS file handling and let users with write access to shared storage append to those files. The sources do not name affected driver versions or the fixed release. Teams not using the C driver or GridFS can skip it.","user_interaction":"no","needs_special_setup":"unknown","severity_if_unknown":"medium"},"cost_usd":0.000717,"input_tokens":4172,"output_tokens":599,"severity_before":"medium"},"analyst_status":null,"analyst_note":null,"search":"'-120684':14A,17A '-2026':13A,16A 'access':49B,109C 'append':123C 'applic':65B,121C,152C 'area':114C 'arrang':116C 'c':2A,19B,33B,84C 'c-driver':18B 'caus':87C 'code':29B 'condit':117C 'content':42B,97C 'credenti':69B,156C 'cve':12A,15A 'data':62B 'databas':44B,104C 'disclosur':146C 'driver':3A,20B,34B,85C 'expos':60B 'file':11A,28B,41B,79C,96C,127C 'flaw':74C 'gridf':9A,21B,27B,78C 'handl':80C 'hold':106C 'includ':68B,155C 'inform':149C 'initi':73C 'later':54B,122C 'leak':7A 'legaci':26B,77C 'libmongoc':22B 'may':53B,142C 'memori':5A,39B,57B,72C,90C,131C 'memory-initi':71C 'mongodb':1A,23B,32B,83C 'ordinari':47B,107C 'packag':24B 'permit':138C 'process':38B,67B,89C,154C 'read':55B,140C 'record':133C 'result':143C 'sensit':61B,148C 'server':102C 'share':51B,112C 'storag':52B,113C 'store':10A,36B,99C 'treat':93C 'uniniti':4A,37B,88C 'unintend':145C 'user':45B,105C,136C 'valid':95C 'write':48B,108C,129C","nicknames":[],"mitigations":[],"who_affected":"Applications built on the MongoDB C Driver that use legacy GridFS file handling and let users with write access to shared storage append to those files. The sources do not name affected driver versions or the fixed release. Teams not using the C driver or GridFS can skip it.","tier":"C","verified":{},"analyst_revisit_at":null,"fix_status":"none","audience":"developers","plain_action":null,"pkeys":[],"ptokens":[],"labels":["cdriver","gridfs","libmongoc","medium","mongodb","package"],"campaign_type":null,"first_public_at":"2026-11-03T19:18:00+00:00","kev":null,"cvss_vector":"CVSS:4.0/AV:N/AC:L/AT:P/PR:L/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-2026-120684","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-120684","severity":null,"published_at":"2026-11-03T19:18:00+00:00","modified_at":"2026-11-03T19:18:00+00:00","first_seen_at":"2026-11-03T19:44:52+00:00","fetched_at":"2026-11-03T19:44:52+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"}