Apache bRPC up to 1.17.x mcpack2pb recursion

Summaryinfo

A vulnerability identified as problematic has been detected in Apache bRPC up to 1.17.x. This issue affects some unknown processing of the component mcpack2pb. The manipulation leads to recursion. This vulnerability is traded as CVE-2026-82230. It is possible to initiate the attack remotely. There is no exploit available. You should upgrade the affected component.

Detailsinfo

A vulnerability was found in Apache bRPC up to 1.17.x and classified as problematic. This issue affects some unknown functionality of the component mcpack2pb. The manipulation with an unknown input leads to a recursion vulnerability. Using CWE to declare the problem leads to CWE-674. The product does not properly control the amount of recursion that takes place, consuming excessive resources, such as allocated memory or the program stack. Impacted is availability. The summary by CVE is:

Uncontrolled recursion in the mcpack2pb component in Apache bRPC (version < 1.18.0) on all platforms allows remote attackers to make the server crash via sending deeply nested mcpack data. Root Cause: The bRPC mcpack2pb parser (used to serve nshead_mcpack / ubrpc / public_pbrpc requests) recursively parses nested objects and arrays without any depth limit. For a protobuf message that references itself (e.g. a repeated message field), the generated parser recurses once per nesting level of the incoming mcpack object. A deeply nested request makes the recursion grow unbounded, overflow the stack and crash the process. Affected Scenarios: Use bRPC server with a recursive-schema protobuf message to serve nshead_mcpack / ubrpc / public_pbrpc requests from untrusted network. 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/3499 Note: No matter which option you choose, you should know that the fix enforces the documented parsing depth limit MAX_DEPTH (128) on the parse path, the same limit the serializer already applies. If your requests contain mcpack messages nested deeper than 128 levels, the request will be failed after applying the fix.

The advisory is shared at lists.apache.org. The identification of this vulnerability is CVE-2026-82230 since 08/28/2026. The exploitation is known to be easy. The attack may be initiated remotely. No form of authentication is needed for a successful exploitation. Neither technical details nor an exploit are publicly available. The price for an exploit might be around USD $0-$5k at the moment (estimation calculated on 10/21/2026). MITRE ATT&CK project uses the attack technique T1499 for this issue.

Upgrading to version 1.18.0 eliminates this vulnerability.

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Productinfo

Vendor

• Apache

Name

• bRPC

Version

• 1.0
• 1.1
• 1.2
• 1.3
• 1.4
• 1.5
• 1.6
• 1.7
• 1.8
• 1.9
• 1.10
• 1.11
• 1.12
• 1.13
• 1.14
• 1.15
• 1.16
• 1.17

License

• open-source

Website

• Vendor: https://www.apache.org/

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