Live › vulnerability › CVE-2026-78048
Go to dashboardA remote client can send a crafted sequence of HPACK-compressed HTTP/2 headers to a bRPC server, tripping an assertion that aborts the whole process. The result is a denial of service with no authentication needed.
Summary written from the sources below. Check the originals before acting.
First seen by InfraStack 2026-10-23 21:57 UTC. All times on this page are UTC.
Any bRPC server that accepts HTTP/2 or gRPC requests from an untrusted network is exposed, because HPACK header decoding runs on every incoming request before any authentication. Servers that only speak HTTP/1.x, or that are reachable only from trusted internal networks, are less exposed. Teams not running bRPC can skip it.
No product ranges from the sources yet.
grep -rn "brpc" CMakeLists.txt or check your lock files and build manifests for the bRPC version in use1.18.0 on any server that accepts HTTP/2 or gRPC traffic from untrusted networks1.18.0 or laterEach row is the first time that source carried this signal. The analyst’s rows are its own findings.
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.
Root Cause: 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 >= 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.
Affected Scenarios: 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.
How to Fix: (Choose one of the following options)
Note: 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).
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