CVE Catalog

CVE-2026-78058

Low risk· EPSS 22%
Published: Updated: Translated: NVD NIST

Exploitation Probability (EPSS)

Low risk
0.31%

22th percentile - higher than 22% of all known CVEs

Summary

Apache bRPC versions < 1.18.0 contain an uncontrolled resource consumption vulnerability in the HTTP/2 (h2) receive path. A remote unauthenticated attacker can send crafted HTTP/2 frames to crash the server or cause unbounded memory growth. The root cause is that receive-side limits (e.g., MAX_CONCURRENT_STREAMS, MAX_HEADER_LIST_SIZE) are advertised but never enforced, and control-frame acks bypass the write buffer cap.

Risk Assessment

Any bRPC server serving HTTP/h2/gRPC to an untrusted network, and any bRPC h2/gRPC client connecting to an untrusted backend, is exposed. An attacker can cause denial of service (crash) or memory exhaustion, and the h2 parser runs before any Authenticator check.

Recommendation

Upgrade Apache bRPC to version 1.18.0 or later, or apply the patch from https://github.com/apache/brpc/pull/3474. After the fix, default limits are enforced: 1024 concurrent streams per connection, 1 MiB decoded header list size per stream, and control-frame acks respect the write buffer cap.

Other vulnerabilities in Apache bRPC

See all
Original NVD description (English source)

Uncontrolled resource consumption in the HTTP/2 (h2) receive path of Apache bRPC (version < 1.18.0) on all platforms allows a remote unauthenticated attacker to crash the server or grow its memory without bound by sending crafted HTTP/2 frames. Root Cause: The h2 parser, enabled by default on every bRPC server port and used by h2/gRPC clients, trusts the peer to respect receive-side limits that bRPC advertises but never enforces: 1. SETTINGS_MAX_CONCURRENT_STREAMS defaulted to unlimited and was never checked on the server, letting a peer pin an unbounded number of pending streams per connection (~100x memory amplification). 2. SETTINGS_MAX_HEADER_LIST_SIZE defaulted to unlimited and was never enforced; 1-byte HPACK indexed references amplify a small HEADERS frame ~4000x into an unbounded decoded header list ("HPACK bomb"), and a never-completed HEADERS/CONTINUATION block accumulates memory without limit. 3. Control-frame acks (PING/SETTINGS acks, RST_STREAM, GOAWAY, WINDOW_UPDATE) unconditionally bypassed the -socket_max_unwritten_bytes write cap, so a PING flood combined with withheld TCP reads grew the connection buffer without the documented bound. 4. The HPACK dynamic table size update was validated against the protocol default (4096) instead of the advertised SETTINGS_HEADER_TABLE_SIZE, which together with the dynamic-table queue/accounting issue can desynchronize the decoder and dereference NULL (crash). Affected scenarios: Any bRPC server serving HTTP/h2/gRPC to an untrusted network, and any bRPC h2/gRPC client connecting to an untrusted backend. The h2 parser runs before any Authenticator check on the shared port. How to fix: Upgrade bRPC, or apply the patch in https://github.com/apache/brpc/pull/3474. Note: After applying the fix the following limits are enforced by default: - max_concurrent_streams: 1024 per connection (4294967295 restores unlimited). - max_header_list_size: 1 MiB decoded size per stream (4294967295 restores unlimited; -h2_client_max_header_list_size for clients). - h2 control-frame acks respect -socket_max_unwritten_bytes (-h2_ack_ignore_eovercrowded restores the old behavior). Requests exceeding these limits are rejected (RST_STREAM(REFUSED_STREAM) or a connection error).

Vulnerability data from NVD (NIST) · CISA KEV · EPSS