{"id":"CVE-2026-86147","kind":"vulnerability","aliases":["CVE-2026-86147"],"related":[],"title":"Apache bRPC: builtin services let remote users write files and stall profilers","description":"External control of file name or path and uncontrolled resource consumption in Apache bRPC (version < 1.18.0) on all platforms allows remote attackers who can reach the builtin service port to create directories and truncate/overwrite files with the privileges of the server process, or to hold the process-wide CPU/contention profiler for an arbitrarily long time.\n\nRoot Cause:\n1. The builtin /flags service allows gflags carrying a validator to be modified at runtime via ?setvalue=. The bvar/mbvar dump path gflags (bvar_dump_file, bvar_dump_tabs, mbvar_dump_file) were registered with an accept-anything validator whose only purpose was to wake the dumping thread. A remote attacker could therefore repoint the dump path (e.g. GET /flags/bvar_dump_file?setvalue=/victim/dir/target followed by GET /flags/bvar_dump?setvalue=true, or the equivalent for mbvar_dump_file, which is used verbatim without a forced suffix), making the dumping thread recursively create directories and open/truncate files at attacker-chosen locations. Tab names in bvar_dump_tabs were appended to the path without sanitization, allowing '..' to escape the configured directory.\n2. The /pprof builtin service did not clamp the ?seconds= parameter to FLAGS_max_profiling_seconds (a limit that /hotspots enforced). A single request such as ?seconds=2147483647 made the handler sleep for decades while holding the process-wide gperftools CPU profiler or bthread contention profiler, so /hotspots/cpu and /hotspots/contention returned 503 for everyone else during that time.\n\nAffected Scenarios:\nAny Apache bRPC server exposing the builtin services (enabled by default on the same port as normal RPC traffic) to untrusted networks.\n\nHow to Fix:\n(Choose one of the following options)\n1. Upgrade bRPC to version 1.18.0, which fixes this issue.\n2. Apply this patch:  https://github.com/apache/brpc/pull/3523 \n\nNote:\nAfter the fix, bvar_dump_file, bvar_dump_tabs and mbvar_dump_file can no longer be modified at runtime through the /flags builtin service. They can still be changed programmatically via google::SetCommandLineOption(), taking effect on the next dump cycle. The profiling duration of /pprof is now capped by the -max_profiling_seconds gflag (default 300 seconds), which can be adjusted by the server owner.","summary":"Apache bRPC versions before 1.18.0 expose builtin /flags and /pprof services on the RPC port, letting a remote attacker repoint the bvar dump path to create directories and overwrite files as the server process. The same services let an attacker hold the process-wide CPU or contention profiler for an arbitrarily long time.","severity":"unknown","cvss":null,"epss":0.00203,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["apache-brpc","bրpc","c++","package","self-hosted"],"not_affected_if":["bvar-dump-disabled","internal-network-only","version-1.18.0-or-later"],"how_to_check":"- Check the bRPC version the server links against, for example `grep -r brpc` in the build files or the version in the package manifest, and see whether it is below `1.18.0`\n- Check whether the builtin services are reachable from untrusted networks on the RPC port, for example with `curl http://<host>:<port>/flags`","fix":"- Upgrade bRPC to `1.18.0`\n- Or apply the patch from https://github.com/apache/brpc/pull/3523\n- Restrict access to the builtin service port from untrusted networks until upgraded","status":"open","published_at":"2026-10-21T13:20:04+00:00","first_seen_at":"2026-10-23T21:57:28+00:00","triaged_at":"2026-10-25T05:02:23+00:00","updated_at":"2026-10-25T05:02:23+00:00","category":"package","confidence":0.7,"triage":{"at":"2026-10-25T05:02:23Z","model":"claude-haiku-5-5","output":{"fix":"- Upgrade bRPC to `1.18.0`\n- Or apply the patch from https://github.com/apache/brpc/pull/3523\n- Restrict access to the builtin service port from untrusted networks until upgraded","reach":"internet","title":"Apache bRPC: builtin services let remote users write files and stall profilers","impact":"high","summary":"Apache bRPC versions before 1.18.0 expose builtin /flags and /pprof services on the RPC port, letting a remote attacker repoint the bvar dump path to create directories and overwrite files as the server process. The same services let an attacker hold the process-wide CPU or contention profiler for an arbitrarily long time.","category":"package","nicknames":[],"who_cares":["bրpc","c++","self-hosted","apache-brpc"],"confidence":0.7,"needs_auth":"no","worst_case":"Remote attacker writes files and truncates data as the server process","analyst_note":"Confirm from the NVD or advisory page whether the file write needs builtin services enabled by default and check the fix commit in PR 3523 for exact scope.","how_to_check":"- Check the bRPC version the server links against, for example `grep -r brpc` in the build files or the version in the package manifest, and see whether it is below `1.18.0`\n- Check whether the builtin services are reachable from untrusted networks on the RPC port, for example with `curl http://<host>:<port>/flags`","needs_analyst":true,"not_affected_if":["bvar-dump-disabled","internal-network-only","version-1.18.0-or-later"],"who_is_affected":"Any server built on Apache bRPC below 1.18.0 that exposes the builtin services on a port reachable from untrusted networks. The builtin services are enabled by default on the same port as normal RPC traffic, so default deployments are exposed if that port is reachable. Servers that keep the RPC port on a trusted internal network are at much lower risk.","user_interaction":"no","needs_special_setup":"no","severity_if_unknown":"unknown"},"cost_usd":0.000755,"input_tokens":4090,"output_tokens":693,"severity_before":"unknown"},"analyst_status":null,"analyst_note":null,"search":"'-2026':14A,17A '-86147':15A,18A '/apache/brpc/pull/3523':365C '/flags':35B,143C,389C '/flags/bvar_dump':205C '/flags/bvar_dump_file':199C '/hotspots':276C '/hotspots/contention':307C '/hotspots/cpu':305C '/pprof':37B,259C,412C '/victim/dir/target':201C '1':140C,349C '1.18.0':32B,97C,354C '2':257C,359C '2147483647':284C '300':423C '503':309C 'accept':176C 'accept-anyth':175C 'adjust':428C 'affect':316C 'allow':101C,145C,251C 'anyth':177C 'apach':1A,20B,28B,94C,319C 'apache-brpc':19B 'append':245C 'appli':360C 'arbitrarili':79B,135C 'attack':46B,67B,103C,190C,235C 'attacker-chosen':234C 'brpc':2A,21B,29B,95C,320C,351C 'bthread':301C 'builtin':3A,34B,108C,142C,260C,324C,390C 'bvar':49B,162C,165C,241C,370C,373C 'bvar/mbvar':158C 'bրpc':22B 'c':23B 'cap':415C 'carri':147C 'caus':139C 'chang':396C 'choos':343C 'chosen':236C 'clamp':264C 'configur':255C 'consumpt':92C 'content':75B,302C 'control':83C 'could':191C 'cpu':73B,298C 'cpu/contention':131C 'creat':53B,112C,228C 'cve':13A,16A 'cycl':407C 'decad':290C 'default':328C,422C 'directori':54B,113C,229C,256C 'dump':50B,159C,163C,166C,169C,186C,195C,213C,225C,242C,371C,374C,378C,406C 'durat':410C 'e.g':197C 'effect':402C 'els':312C 'enabl':326C 'enforc':277C 'equival':210C 'escap':253C 'everyon':311C 'expos':33B,322C 'extern':82C 'file':9A,57B,85C,116C,164C,170C,214C,232C,372C,379C 'fix':342C,356C,369C 'flag':269C 'follow':202C,347C 'forc':221C 'get':198C,204C 'gflag':146C,161C,421C 'github.com':364C 'github.com/apache/brpc/pull/3523':363C 'googl':399C 'gperftool':297C 'handler':287C 'hold':68B,126C,292C 'host':27B 'issu':358C 'let':5A,43B,65B 'limit':274C 'locat':237C 'long':80B,136C 'longer':382C 'made':285C 'make':223C 'max':270C,418C 'mbvar':168C,212C,377C 'modifi':152C,384C 'name':86C,239C 'network':339C 'next':405C 'normal':334C 'note':366C 'one':344C 'open/truncate':231C 'option':348C 'overwrit':56B 'owner':432C 'packag':24B 'paramet':267C 'patch':362C 'path':51B,88C,160C,196C,248C 'platform':100C 'port':42B,110C,332C 'privileg':119C 'process':61B,71B,123C,129C,295C 'process-wid':70B,128C,294C 'profil':12A,76B,132C,271C,299C,303C,409C,419C 'programmat':397C 'purpos':181C 'reach':106C 'recurs':227C 'regist':172C 'remot':6A,45B,102C,189C 'repoint':47B,193C 'request':280C 'resourc':91C 'return':308C 'root':138C 'rpc':41B,335C 'runtim':154C,386C 'sanit':250C 'scenario':317C 'second':266C,272C,283C,420C,424C 'self':26B 'self-host':25B 'server':60B,122C,321C,431C 'servic':4A,38B,64B,109C,144C,261C,325C,391C 'setcommandlineopt':400C 'setvalu':156C,200C,206C 'singl':279C 'sleep':288C 'stall':11A 'still':394C 'suffix':222C 'tab':167C,238C,243C,375C 'take':401C 'therefor':192C 'thread':187C,226C 'time':81B,137C,315C 'traffic':336C 'true':207C 'truncate/overwrite':115C 'uncontrol':90C 'untrust':338C 'upgrad':350C 'use':217C 'user':7A 'valid':149C,178C 'verbatim':218C 'version':30B,96C,353C 'via':155C,398C 'wake':184C 'whose':179C 'wide':72B,130C,296C 'without':219C,249C 'write':8A","nicknames":[],"mitigations":[],"who_affected":"Any server built on Apache bRPC below 1.18.0 that exposes the builtin services on a port reachable from untrusted networks. The builtin services are enabled by default on the same port as normal RPC traffic, so default deployments are exposed if that port is reachable. Servers that keep the RPC port on a trusted internal network are at much lower risk.","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-2026-86147","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-86147","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-2026-86147","url":"https://api.first.org/data/v1/epss?cve=CVE-2026-86147","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"}