CVE-2026-78066
Apache bRPC: Resource Exhaustion via Unbounded Decompression and Unvalidated Wire-Declared Sizes
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).
INFO
Published Date :
Oct. 21, 2026, 12:17 p.m.
Last Modified :
Oct. 21, 2026, 12:17 p.m.
Remotely Exploit :
No
Source :
[email protected]
Solution
- Upgrade Apache bRPC to version 1.18.0.
- Apply the provided patch for versions below 1.18.0.
- Configure new limits if legitimate large values are needed.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-78066.
| URL | Resource |
|---|---|
| https://lists.apache.org/thread/2pf15ojj0vr7rtx95677kgtl1mx3gdgb |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-78066 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-78066
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-78066 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-78066 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
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New CVE Received by [email protected]
Oct. 21, 2026
Action Type Old Value New Value Added 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). Added CWE CWE-770 Added Affected New affected value received. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/78xxx/CVE-2026-78066.json">CVE-2026-78066</a> Added Reference https://lists.apache.org/thread/2pf15ojj0vr7rtx95677kgtl1mx3gdgb