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CVE-2026-56386— Apache bRPC: Integer Underflow and Out-of-Bounds Read in HTTP/2 DATA Frame Parser

Quick assessment

Affected
Apache Software Foundation Apache bRPC
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Apache bRPC 的 HTTP/2 服务器中，DATA 帧解析器存在整数下溢和越界读取漏洞。未认证的远程攻击者可通过发送一个设置了 PADDED 标志且负载长度为零的畸形 DATA 帧，触发拒绝服务（DoS）攻击。 根本原因： HTTP/2 DATA 帧处理器根据攻击者控制的负载长度计算分片大小；当存在 PADDED 标志时，该处理器在未先确认帧中包含必需的填充长度字节之前，就提前对分片大小进行了递减操作。因此，一个零长度的带填充 DATA 帧会导致无符号分片大小发生下溢，进而尝试在帧缓冲区末尾之外读取填充长

AI Predicted 5.3 Difficulty: Trivial

Affected Version Matrix 1

VendorProduct Version RangeStatus
Apache Software Foundation Apache bRPC < 1.18.0 affected
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I. Basic Information for CVE-2026-56386

Vulnerability Information
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Vulnerability Title
Apache bRPC: Integer Underflow and Out-of-Bounds Read in HTTP/2 DATA Frame Parser
Source: CVE Program / CVE List V5
Vulnerability Description
Integer underflow and out-of-bounds read in the HTTP/2 server DATA frame parser in Apache bRPC allows an unauthenticated remote attacker to cause denial of service by sending a malformed DATA frame with the PADDED flag set and a zero-length payload. Root Cause: The HTTP/2 DATA frame handler computed the fragment size from the attacker-controlled payload length and, when the PADDED flag was present, decremented the fragment size before ensuring that the frame contained the mandatory pad length byte. A zero-length padded DATA frame could therefore underflow the unsigned fragment size and read the pad length byte past the end of the frame buffer. Affected Scenarios: Apache bRPC servers that accept HTTP/2 traffic are affected when a remote client can send crafted HTTP/2 frames to the server. HTTP/2 may be reached through cleartext h2c detection on an HTTP port or through TLS ALPN negotiation. How to Fix: (Choose one of the following options) 1. Upgrade Apache bRPC to version 1.18.0, which fixes this issue. 2. Apply this patch: https://github.com/apache/brpc/pull/3325 Note: The fix validates that a padded DATA frame has enough payload bytes for the pad length field before decrementing the fragment size or reading the pad length byte. Malformed zero-length padded DATA frames are rejected with HTTP/2 FRAME_SIZE_ERROR.
Source: CVE Program / CVE List V5
CVSS Information
N/A
Source: CVE Program / CVE List V5
Vulnerability Type
整数下溢(超界折返)
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
Apache Software Foundation Apache bRPC 0 ~ 1.18.0 -

II. Public POCs for CVE-2026-56386

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III. Intelligence Information for CVE-2026-56386

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Same Patch Batch · Apache Software Foundation · 2026-10-21 · 69 CVEs total

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CVE-2026-111815 10.0 CRITICAL Apache Traffic Server: TLS session ticket resumption bypasses per-SNI verify_client STRICT
CVE-2026-111814 10.0 CRITICAL Apache Traffic Server: Default server_session_sharing.match omits MASK_CERT, allowing pool
CVE-2026-111809 9.3 CRITICAL Apache Traffic Server: HEAD requests carrying Content-Length or Transfer-Encoding enable r
CVE-2026-111816 9.3 CRITICAL Apache Traffic Server: A malformed 302 response bypasses parse-error rejection through the
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CVE-2026-111811 9.0 CRITICAL Apache Traffic Server: tsmemcache plugin exposes the shared proxy cache over the network w
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CVE-2025-55702 8.7 HIGH Apache Traffic Server: An unread Expect: 100-continue request body is framed as a new requ
CVE-2026-111808 8.6 HIGH Apache Traffic Server: HTTP/2 DATA frame padding underflow lets a client trigger backend w
CVE-2026-111805 8.6 HIGH Apache Traffic Server: HTTP/2 Content-Length truncation lets a client trigger backend work
CVE-2026-111804 8.2 HIGH Apache Traffic Server: wasm plugin has a use-after-free and forwards unvalidated guest met
CVE-2026-105945 7.7 HIGH Apache Pulsar: Improper Validation of Package Name Components Allows Cross-Tenant Package
CVE-2026-105942 7.7 HIGH Apache Pulsar: Original principal of proxied requests authorized with the proxy's authenti
CVE-2026-111810 7.5 HIGH Apache Traffic Server: Unthrottled per-header diagnostic logging enables a log-flood denia
CVE-2026-105934 7.2 HIGH Apache Pulsar: Missing tenant admin authorization check when truncating a partitioned topi
CVE-2026-105930 6.0 MEDIUM Apache Pulsar: Improper Authorization of Function, Source and Sink Package URLs Allows Cro

Showing top 20 of 69 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Apache bRPC
Same vendor: Apache Software Foundation
Same weakness: CWE-191

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