{"id":"CVE-2026-87849","kind":"vulnerability","aliases":["CVE-2026-87849"],"related":[],"title":"Apache bRPC: malformed Discovery reply crashes clients that refresh server lists","description":"The Discovery naming-service reply parser in Apache bRPC (versions < 1.18.0) calls RapidJSON object-only accessors (FindMember) on JSON values without first validating that those values are objects. A malformed Discovery response whose data/service members or instances list contain non-object entries (e.g. a bare integer) triggers the RapidJSON object-access precondition on the client, reading memory out of bounds and potentially crashing the bRPC client.\n\nRoot Cause:\nIn src/brpc/policy/discovery_naming_service.cpp, DiscoveryNamingService::GetServers() and DiscoveryNames::ListDiscoveryNodes() access JSON values with member functions on non-object values. RapidJSON only defines these operations for object types; invoking them on a non-object violates the class invariant and results in undefined behavior (out-of-bounds read), commonly crashing the process.\n\nAffected Scenarios: \nAn operator-configured (or compromised) Discovery backend returns a malformed /discovery/nodes or /discovery/fetchs response whose data/service/instance entries are not JSON objects, crashing any bRPC client that refreshes its server list.\n\nHow to Fix:\n1. Upgrade bRPC to version 1.18.0 or later, which fixes this issue.\n2. Apply this patch: https://github.com/apache/brpc/pull/3533\n\nThe fix validates that the Discovery response data, per-service data, and instance entries are JSON objects (and skips non-object node/instance entries and rejects non-object data/service values) before calling member accessors.","summary":"The Discovery naming-service reply parser in Apache bRPC before 1.18.0 calls object-only JSON accessors on values that may not be objects, causing out-of-bounds memory reads. An attacker controlling or compromising the Discovery backend can crash any bRPC client that refreshes its server list.","severity":"medium","cvss":null,"epss":0.00159,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["brpc","c++","discovery-naming-service","package","rpc-clients"],"not_affected_if":["backend-trusted","not-using-discovery-naming-service"],"how_to_check":"- Check the bRPC version in use, for example with `grep -ri brpc` in your build files or `ldd` on the binary, and compare it to `1.18.0`\n- Look for use of the Discovery naming service, for example URLs with `discovery://` in client configuration","fix":"- Upgrade Apache bRPC to `1.18.0` or later\n- Or apply the patch from https://github.com/apache/brpc/pull/3533","status":"open","published_at":"2026-10-21T13:20:04+00:00","first_seen_at":"2026-10-23T21:57:28+00:00","triaged_at":"2026-10-25T05:02:19+00:00","updated_at":"2026-10-25T05:02:19+00:00","category":"package","confidence":0.6,"triage":{"at":"2026-10-25T05:02:19Z","model":"claude-haiku-5-5","output":{"fix":"- Upgrade Apache bRPC to `1.18.0` or later\n- Or apply the patch from https://github.com/apache/brpc/pull/3533","reach":"network","title":"Apache bRPC: malformed Discovery reply crashes clients that refresh server lists","impact":"medium","summary":"The Discovery naming-service reply parser in Apache bRPC before 1.18.0 calls object-only JSON accessors on values that may not be objects, causing out-of-bounds memory reads. An attacker controlling or compromising the Discovery backend can crash any bRPC client that refreshes its server list.","category":"package","nicknames":[],"who_cares":["brpc","c++","discovery-naming-service","rpc-clients"],"confidence":0.6,"needs_auth":"unknown","worst_case":"bRPC client process crashes from out-of-bounds memory read","analyst_note":"","how_to_check":"- Check the bRPC version in use, for example with `grep -ri brpc` in your build files or `ldd` on the binary, and compare it to `1.18.0`\n- Look for use of the Discovery naming service, for example URLs with `discovery://` in client configuration","needs_analyst":false,"not_affected_if":["not-using-discovery-naming-service","backend-trusted"],"who_is_affected":"Only clients that use bRPC's Discovery naming service to refresh server lists are exposed, and the trigger requires a malformed /discovery/nodes or /discovery/fetchs response from the Discovery backend. Teams not using the Discovery naming service can skip it, though they should still confirm the bRPC version.","user_interaction":"no","needs_special_setup":"yes","severity_if_unknown":"medium"},"cost_usd":0.000671,"input_tokens":3773,"output_tokens":588,"severity_before":"unknown"},"analyst_status":null,"analyst_note":null,"search":"'-2026':13A,16A '-87849':14A,17A '/apache/brpc/pull/3533':255C '/discovery/fetchs':216C '/discovery/nodes':214C '1':237C '1.18.0':39B,89C,242C '2':249C 'access':132C,157C 'accessor':45B,95C,291C 'affect':201C 'apach':1A,36B,86C 'appli':250C 'attack':61B 'backend':67B,210C 'bare':125C 'behavior':191C 'bound':57B,141C,195C 'brpc':2A,18B,37B,71B,87C,146C,227C,239C 'c':19B 'call':40B,90C,289C 'caus':53B,149C 'class':185C 'client':7A,27B,72B,136C,147C,228C 'common':197C 'compromis':64B,208C 'configur':206C 'contain':118C 'control':62B 'crash':6A,69B,144C,198C,225C 'cve':12A,15A 'data':263C,267C 'data/service':113C,286C 'data/service/instance':219C 'defin':170C 'discoveri':4A,21B,29B,66B,79C,110C,209C,261C 'discovery-naming-servic':20B 'discoverynam':155C 'discoverynamingservic':152C 'e.g':123C 'entri':122C,220C,270C,280C 'findmemb':96C 'first':101C 'fix':236C,246C,257C 'function':162C 'getserv':153C 'github.com':254C 'github.com/apache/brpc/pull/3533':253C 'instanc':116C,269C 'integ':126C 'invari':186C 'invok':176C 'issu':248C 'json':44B,98C,158C,223C,272C 'later':244C 'list':11A,77B,117C,233C 'listdiscoverynod':156C 'malform':3A,109C,213C 'may':49B 'member':114C,161C,290C 'memori':58B,138C 'name':22B,31B,81C 'naming-servic':30B,80C 'node/instance':279C 'non':120C,165C,181C,277C,284C 'non-object':119C,164C,180C,276C,283C 'object':42B,52B,93C,107C,121C,131C,166C,174C,182C,224C,273C,278C,285C 'object-access':130C 'object-on':41B,92C 'oper':172C,205C 'operator-configur':204C 'out-of-bound':54B,192C 'packag':24B 'parser':34B,84C 'patch':252C 'per':265C 'per-servic':264C 'potenti':143C 'precondit':133C 'process':200C 'rapidjson':91C,129C,168C 'read':59B,137C,196C 'refresh':9A,74B,230C 'reject':282C 'repli':5A,33B,83C 'respons':111C,217C,262C 'result':188C 'return':211C 'root':148C 'rpc':26B 'rpc-client':25B 'scenario':202C 'server':10A,76B,232C 'servic':23B,32B,82C,266C 'skip':275C 'src/brpc/policy/discovery_naming_service.cpp':151C 'trigger':127C 'type':175C 'undefin':190C 'upgrad':238C 'valid':102C,258C 'valu':47B,99C,105C,159C,167C,287C 'version':88C,241C 'violat':183C 'whose':112C,218C 'without':100C","nicknames":[],"mitigations":[],"who_affected":"Only clients that use bRPC's Discovery naming service to refresh server lists are exposed, and the trigger requires a malformed /discovery/nodes or /discovery/fetchs response from the Discovery backend. Teams not using the Discovery naming service can skip it, though they should still confirm the bRPC version.","tier":"C","verified":{},"analyst_revisit_at":null,"first_public_at":"2026-10-21T13:20:04+00:00","kev":null,"cvss_vector":null,"cvss_by":null,"poc_count":0,"sources":[{"source":"nvd","external_id":"CVE-2026-87849","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-87849","severity":null,"published_at":"2026-10-21T13:20:04+00:00","modified_at":"2026-10-22T16:56:37+00:00","first_seen_at":"2026-10-23T21:57:28+00:00","fetched_at":"2026-10-23T22:29:01+00:00","note":null},{"source":"epss","external_id":"CVE-2026-87849","url":"https://api.first.org/data/v1/epss?cve=CVE-2026-87849","severity":null,"published_at":null,"modified_at":null,"first_seen_at":"2026-10-24T13:15:54+00:00","fetched_at":"2026-10-24T13:15:54+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"}