Unscored severity · published Oct 21, 2026
CVE-2026-78066
Apache bRPC: Resource Exhaustion via Unbounded Decompression and Unvalidated Wire-Declared Sizes
–
CVSS
0.2%
EPSS
No
On KEV
Description
Resource exhaustion in Apache bRPC (version < 1.18.0) on all platforms: multiple parsers that accept wire-controlled input bound no limit on the sizes declared by the client or on decompressed output, which attackers can use to drive disproportionate memory use and crash the process.
Root Cause:
1) The gzip/zlib/snappy decompressors enforce no output limit: -max_body_size is checked against the compressed bytes only, so a cap-compliant body (e.g. 64 MiB) can decompress to tens of GiB.
2) The AMF string readers allocate the declared length before the bytes are actually available.
3) RTMP chunk headers may re-declare a message length mid-stream; the declared length was never bounded and the partial reassembly buffer kept growing.
4) The sofa-pbrpc parser does not bound meta_size.
5) mcpack2pb trusts wire-declared item counts for Reserve() and a string value_size of 0 underflows the buffer size, aborting the process.
Affected Scenarios:
Any bRPC service accepting gzip/zlib/snappy-compressed bodies or rtmp, sofa-pbrpc, or mcpack2pb messages from untrusted clients.
How to Fix:(Choose one of the following options) 1. Upgrade bRPC to version 1.18.0, which fixes this issue.
2. Apply this patch: https://github.com/apache/brpc/pull/3476
Note:
After the fix, requests whose decompressed size, RTMP message length, or mcpack declared count exceed the new limits are rejected. Operators who legitimately need larger values can raise the corresponding flag (-max_decompressed_body_size, max_body_size).
Exploitation
Is it being used?
Exploit prediction (EPSS)0.2% · higher than 6% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
AB
Apache bRPC · Apache Software Foundation
before 1.18.0 · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-78066
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-78066
lists.apache.org
https://lists.apache.org/thread/2pf15ojj0vr7rtx95677kgtl1mx3gdgb
More from Apache bRPC
7.5
CVE-2026-82230
Apache bRPC: Stack Exhaustion via Unbounded Recursion in mcpack2pb Parser
7.5
CVE-2026-74757
Apache bRPC: Uncontrolled Memory Allocation via Malicious mcpack Array Item Count
7.5
CVE-2026-56386
Apache bRPC: Integer Underflow and Out-of-Bounds Read in HTTP/2 DATA Frame Parser
6.5
CVE-2026-90484
Apache bRPC: Null pointer dereference in MySQL reply parser leading to client crash
5.4
CVE-2026-84727
Apache bRPC: Use-After-Free in RTMP Chunk Stream Handling via Abort Message
