{"id":"CVE-2026-123610","kind":"vulnerability","aliases":["CVE-2026-123610"],"related":[],"title":"rustls: Brotli certificate decompression lets a peer exhaust memory","description":"rustls before 0.23.46 contains an uncontrolled memory allocation flaw in its optional Brotli certificate decompression, which limits decompressed output size but accepts an input-selected large history window. Malicious peers can send a certificate with a five-byte Brotli header requesting up to 1 GiB before authentication, aborting Brotli-enabled clients or client-authenticating servers whose allocator cannot satisfy the request.","summary":"rustls before 0.23.46 accepts an oversized Brotli history window in optional certificate decompression. A malicious peer can send a tiny certificate header before authentication that requests up to 1 GiB and aborts the client or server process.","severity":"medium","cvss":6.3,"epss":null,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["package","rust","rustls","self-hosted","tls"],"not_affected_if":["brotli-feature-disabled","default-config"],"how_to_check":"- Check the locked rustls version in `Cargo.lock` for `rustls` below `0.23.46`.\n- Check whether the build enables Brotli certificate decompression (the optional rustls feature for certificate compression).","fix":"- `rustls` moves to `0.23.46` or later.","status":"open","published_at":"2026-11-08T02:16:56+00:00","first_seen_at":"2026-11-08T02:21:14+00:00","triaged_at":"2026-11-08T02:24:52+00:00","updated_at":"2026-11-08T02:24:52+00:00","category":"package","confidence":0.6,"triage":{"at":"2026-11-08T02:24:52Z","model":"claude-haiku-5-5","output":{"fix":"- `rustls` moves to `0.23.46` or later.","reach":"network","title":"rustls: Brotli certificate decompression lets a peer exhaust memory","impact":"medium","summary":"rustls before 0.23.46 accepts an oversized Brotli history window in optional certificate decompression. A malicious peer can send a tiny certificate header before authentication that requests up to 1 GiB and aborts the client or server process.","audience":"developers","category":"package","nicknames":[],"who_cares":["rust","rustls","tls","self-hosted"],"confidence":0.6,"fix_status":"available","needs_auth":"no","worst_case":"remote peer aborts a Brotli-enabled rustls process by memory exhaustion","analyst_note":"","how_to_check":"- Check the locked rustls version in `Cargo.lock` for `rustls` below `0.23.46`.\n- Check whether the build enables Brotli certificate decompression (the optional rustls feature for certificate compression).","plain_action":"","needs_analyst":false,"not_affected_if":["default-config","brotli-feature-disabled"],"who_is_affected":"Rust applications that use rustls with the optional Brotli certificate decompression enabled, on either the client side or as a server that requests client certificates. Applications that do not enable that feature, or that run only on allocators able to satisfy the request, are less exposed; the sources do not say more.","user_interaction":"no","needs_special_setup":"yes","severity_if_unknown":"unknown"},"cost_usd":0.000689,"input_tokens":4308,"output_tokens":517,"severity_before":"medium"},"analyst_status":null,"analyst_note":null,"search":"'-123610':12A,15A '-2026':11A,14A '0.23.46':25B,62C '1':51B,105C 'abort':54B,109C 'accept':26B,81C 'alloc':67C,120C 'authent':46B,108C,117C 'brot':2A,29B,72C,100C,111C 'brotli-en':110C 'byte':99C 'cannot':121C 'certif':3A,34B,43B,73C,94C 'client':56B,113C,116C 'client-authent':115C 'contain':63C 'cve':10A,13A 'decompress':4A,35B,74C,77C 'enabl':112C 'exhaust':8A 'five':98C 'five-byt':97C 'flaw':68C 'gib':52B,106C 'header':44B,101C 'histori':30B,87C 'host':21B 'input':84C 'input-select':83C 'larg':86C 'let':5A 'limit':76C 'malici':37B,89C 'memori':9A,66C 'option':33B,71C 'output':78C 'overs':28B 'packag':16B 'peer':7A,38B,90C 'process':59B 'request':48B,102C,124C 'rust':17B 'rustl':1A,18B,23B,60C 'satisfi':122C 'select':85C 'self':20B 'self-host':19B 'send':40B,92C 'server':58B,118C 'size':79C 'tini':42B 'tls':22B 'uncontrol':65C 'whose':119C 'window':31B,88C","nicknames":[],"mitigations":[],"who_affected":"Rust applications that use rustls with the optional Brotli certificate decompression enabled, on either the client side or as a server that requests client certificates. Applications that do not enable that feature, or that run only on allocators able to satisfy the request, are less exposed; the sources do not say more.","tier":"C","verified":{},"analyst_revisit_at":null,"fix_status":"available","audience":"developers","plain_action":null,"pkeys":[],"ptokens":[],"labels":["medium","package","rust","rustls","selfhosted","tls"],"campaign_type":null,"search_a":"'-123610':12A,15A '-2026':11A,14A 'brot':2A 'certif':3A 'cve':10A,13A 'decompress':4A 'exhaust':8A 'let':5A 'memori':9A 'peer':7A 'rustl':1A","search_b":"'0.23.46':25B '1':51B 'abort':54B 'accept':26B 'authent':46B 'brot':29B 'certif':34B,43B 'client':56B 'decompress':35B 'gib':52B 'header':44B 'histori':30B 'host':21B 'malici':37B 'option':33B 'overs':28B 'packag':16B 'peer':38B 'process':59B 'request':48B 'rust':17B 'rustl':18B,23B 'self':20B 'self-host':19B 'send':40B 'server':58B 'tini':42B 'tls':22B 'window':31B","search_c":"'0.23.46':62C '1':105C 'abort':109C 'accept':81C 'alloc':67C,120C 'authent':108C,117C 'brot':72C,100C,111C 'brotli-en':110C 'byte':99C 'cannot':121C 'certif':73C,94C 'client':113C,116C 'client-authent':115C 'contain':63C 'decompress':74C,77C 'enabl':112C 'five':98C 'five-byt':97C 'flaw':68C 'gib':106C 'header':101C 'histori':87C 'input':84C 'input-select':83C 'larg':86C 'limit':76C 'malici':89C 'memori':66C 'option':71C 'output':78C 'peer':90C 'request':102C,124C 'rustl':60C 'satisfi':122C 'select':85C 'send':92C 'server':118C 'size':79C 'uncontrol':65C 'whose':119C 'window':88C","first_public_at":"2026-10-14T09:54:52+00:00","kev":null,"cvss_vector":"CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/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":"disclosure@vulncheck.com","poc_count":0,"sources":[{"source":"nvd","external_id":"CVE-2026-123610","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-123610","severity":null,"published_at":"2026-11-08T02:16:56+00:00","modified_at":"2026-11-08T02:16:56+00:00","first_seen_at":"2026-11-08T02:21:14+00:00","fetched_at":"2026-11-08T02:21:14+00:00","note":null}],"documents":[{"id":99371,"url":"https://github.com/rustls/rustls/security/advisories/GHSA-h2v8-394m-p7vv","title":"Vendor advisory: github.com","kind":"vendor","source":"nvd","publisher":"vendor","text":null,"published_at":"2026-10-14T09:54:52+00:00","relation":"advisory","confidence":null,"note":"Vendor advisory: github.com"},{"id":99372,"url":"https://www.vulncheck.com/advisories/rustls-before-0.23.46-denial-of-service-via-brotli-certificate-decompression","title":"Third-party advisory: www.vulncheck.com","kind":"advisory","source":"nvd","publisher":"research","text":null,"published_at":null,"relation":"advisory","confidence":null,"note":"Third-party advisory: www.vulncheck.com"}],"exploit_sources":[],"notice":"Free to read, with fair use of about 60 pages a minute. For higher limits or API access: sales@infrastack.ai"}