{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-78048","assignerOrgId":"f0158376-9dc2-43b6-827c-5f631a4d8d09","state":"PUBLISHED","assignerShortName":"apache","dateReserved":"2026-08-22T04:09:09.653Z","datePublished":"2026-10-21T11:51:58.752Z","dateUpdated":"2026-10-30T16:49:25.386Z"},"containers":{"cna":{"providerMetadata":{"orgId":"f0158376-9dc2-43b6-827c-5f631a4d8d09","shortName":"apache","dateUpdated":"2026-10-21T11:51:58.752Z"},"title":"Apache bRPC: Remote Denial of Service via Out-of-Bounds Dynamic Table Sizing in HPACK Decoder","problemTypes":[{"descriptions":[{"description":"CWE-617 Reachable Assertion","lang":"en","cweId":"CWE-617","type":"CWE"}]}],"source":{"discovery":"EXTERNAL"},"affected":[{"vendor":"Apache Software Foundation","product":"Apache bRPC","packageURL":"pkg:github/apache/brpc","versions":[{"status":"affected","version":"0","lessThan":"1.18.0","versionType":"semver"}],"defaultStatus":"unaffected","collectionURL":"https://github.com","packageName":"apache/brpc"}],"descriptions":[{"value":"A reachable-assertion flaw in the HPACK header-compression decoder of the HTTP/2 (h2/gRPC) stack in Apache bRPC (version < 1.18.0) on all platforms allows a remote attacker to crash the server process by sending a crafted sequence of HPACK headers, resulting in a denial of service.\n\nRoot Cause:\nIn src/brpc/details/hpack.cpp, IndexTable::Init sizes the dynamic-table ring buffer as num_headers = max_size / (32 + 2), i.e. it assumes a minimum table entry of 34 bytes (name >= 1 byte + value >= 1 byte + 32 bytes of overhead). However, RFC 7541 section 4.1 specifies that the minimum entry size is 33 bytes, because the value may be empty (name >= 1 byte + value == 0 + 32 bytes). For the default 4096-byte table this allocates only 120 slots (4096/34). Eviction in AddHeader is driven by byte usage (_max_size), not by slot count, so a peer can add 121 minimal 33-byte entries (121*33 = 3993 <= 4096) without triggering eviction. The 121st AddHeader then hits CHECK(!_header_queue.full()), which aborts the process.\n\nAffected Scenarios:\nUse a bRPC server that serves HTTP/2 or gRPC requests (e.g. via the h2 protocol) from an untrusted network. The malicious header block is processed during HPACK decoding of incoming requests without authentication.\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/3462\n\nNote:\nThe fix sizes the dynamic table for the 33-byte minimum entry (max_size / (32 + 1)) and ensures at least one ring-buffer slot is kept when max_size is smaller than the minimum entry, so that initialization cannot fail on malloc(0).","lang":"en","supportingMedia":[{"type":"text/html","base64":false,"value":"A reachable-assertion flaw in the HPACK header-compression decoder of the HTTP/2 (h2/gRPC) stack in Apache bRPC (version &lt; 1.18.0) on all platforms allows a remote attacker to crash the server process by sending a crafted sequence of HPACK headers, resulting in a denial of service.<br><br>Root Cause:<br>In src/brpc/details/hpack.cpp, IndexTable::Init sizes the dynamic-table ring buffer as num_headers = max_size / (32 + 2), i.e. it assumes a minimum table entry of 34 bytes (name &gt;= 1 byte + value &gt;= 1 byte + 32 bytes of overhead). However, RFC 7541 section 4.1 specifies that the minimum entry size is 33 bytes, because the value may be empty (name &gt;= 1 byte + value == 0 + 32 bytes). For the default 4096-byte table this allocates only 120 slots (4096/34). Eviction in AddHeader is driven by byte usage (_max_size), not by slot count, so a peer can add 121 minimal 33-byte entries (121*33 = 3993 &lt;= 4096) without triggering eviction. The 121st AddHeader then hits CHECK(!_header_queue.full()), which aborts the process.<br><br>Affected Scenarios:<br>Use a bRPC server that serves HTTP/2 or gRPC requests (e.g. via the h2 protocol) from an untrusted network. The malicious header block is processed during HPACK decoding of incoming requests without authentication.<br><br>How to Fix: <br><span>(Choose one of the following options)&nbsp;</span><br>1. Upgrade bRPC to version 1.18.0, which fixes this issue.<br><span>2. Apply this patch:&nbsp;</span>https://github.com/apache/brpc/pull/3462<br><br>Note:<br>The fix sizes the dynamic table for the 33-byte minimum entry (max_size / (32 + 1)) and ensures at least one ring-buffer slot is kept when max_size is smaller than the minimum entry, so that initialization cannot fail on malloc(0)."}]}],"references":[{"url":"https://lists.apache.org/thread/2pf15ojj0vr7rtx95677kgtl1mx3gdgb","tags":["vendor-advisory"]}],"metrics":[{"other":{"type":"Textual description of severity","content":{"text":"high"}},"scenarios":[{"lang":"en","value":"GENERAL"}]}],"credits":[{"lang":"en","value":"ubeddulla khan","type":"finder"}],"x_generator":{"engine":"Vulnogram 0.2.0"}},"adp":[{"metrics":[{"cvssV3_1":{"scope":"UNCHANGED","version":"3.1","baseScore":7.5,"attackVector":"NETWORK","baseSeverity":"HIGH","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","integrityImpact":"NONE","userInteraction":"NONE","attackComplexity":"LOW","availabilityImpact":"HIGH","privilegesRequired":"NONE","confidentialityImpact":"NONE"}},{"other":{"type":"ssvc","content":{"timestamp":"2026-10-30T16:48:59.723519Z","id":"CVE-2026-78048","options":[{"Exploitation":"none"},{"Automatable":"yes"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"title":"CISA ADP Vulnrichment","providerMetadata":{"orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","shortName":"CISA-ADP","dateUpdated":"2026-10-30T16:49:25.386Z"}}]}}