Apache bRPC: Uncontrolled Memory Allocation via Malicious mcpack Array Item Count
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Published
4 h ago
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Vulnerability description
DayBreach AI Explanation
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Evidence confidence
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Short explanation
The mcpack2pb component in Apache bRPC prior to version 1.18.0 contains an uncontrolled resource allocation vulnerability allowing remote attackers to trigger massive memory allocation via crafted mcpack requests.
Parsed before authentication, this flaw enables attackers to force servers to preallocate enormous amounts of virtual memory, potentially causing process termination on resource-constrained hosts.
What should be done?
- Upgrade Apache bRPC to version 1.18.0 or higher.
- Apply the provided patch.
- Follow vendor advisories.
Chain of evidence and sources
Apache bRPC sürüm 1.18.0 öncesi mcpack2pb bileşeni kontrolsüz bellek tahsisine karşı savunmasızdır.
Kötü amaçlı bir istek, sunucuyu yaklaşık 16GB sanal bellek ön tahsisi yapmaya zorlayabilir.
Show the technical text from the sources
Uncontrolled resource allocation in the mcpack2pb component in Apache bRPC (version < 1.18.0) on all platforms allows remote attackers to make the server allocate a large amount of memory via sending a crafted mcpack request with a huge array item count. Root Cause: The bRPC mcpack2pb parser trusts the item count stored in the mcpack array header without validating it against the actual payload size. The code generated by the mcpack2pb protoc plugin uses this count to preallocate memory for repeated protobuf fields via Reserve(). A malformed request declaring item_count = 0x7fffffff can force the server to preallocate about 16GB of virtual memory, which may abort the process (SIGABRT) on memory-constrained hosts. Affected Scenarios: Use a bRPC server that wires a NsheadService to UbrpcMcpack2Adaptor (the Baidu ubrpc deployment pattern) and parses requests with code generated by the mcpack2pb protoc plugin. The request body is parsed before authentication. 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/3451 Note: No matter which option you choose, you should know that the fix caps the array item count to the remaining bytes of the array payload.
CWE: CWE-770
This explanation was compiled automatically from the source records. Scores, active exploitation, patch and exploit status come straight from the sources.
IMPACT: Affected Products and Software
Affected Products
The following products are affected by CVE-2026-74757 vulnerability. Where our threat engine knows the exact affected versions, they are listed below.
| ID | VENDOR | PRODUCT | ACTION |
|---|---|---|---|
| 1 | Apache Software Foundation | Apache bRPC | View |
RED HAT CSAF/VEX: Product Impact Check
SCORING: CVSS from Multiple Sources
CVSS Scores
The Common Vulnerability Scoring System is a standardised framework for assessing the severity of vulnerabilities in software and systems. We collect and display CVSS scores from several sources for each CVE.
| SCORE | VERSION | SEVERITY | VECTOR | SOURCE |
|---|---|---|---|---|
| The sources have not yet published a verified CVSS metric. | ||||
Patch and Remediation Guide
Solution & Remediation Advisory
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Public exploit and active exploitation status
Verified exploit intelligence
No verified public PoC, exploit repository or Metasploit module has been found for this CVE yet.
Weakness Classification and Attack Patterns (CWE & CAPEC)
CWE - Common Weakness Enumeration
While CVE identifies specific instances of vulnerabilities, CWE categorises the common flaws or weaknesses that can lead to vulnerabilities. CVE-2026-74757 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-2026-74757 weaknesses.
Official Sources and Advisories
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Weakness Type (CWE & CAPEC)
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