CVE-2021-46878: treasuredata fluent_bit Type Confusion

Vulnerability summary

CVE-2021-46878 is a high (CVSS 7.8) Type Confusion vulnerability in treasuredata fluent_bit. EPSS estimates a 0.35% chance of exploitation in the next 30 days, higher than 27.1% of scored vulnerabilities. 1 public exploit is recorded.

Timeline

1. 11-04-2023
   PublishedVulnerability first disclosed.
2. 11-02-2025
   Last modifiedVulnerability information updated.

Description

An issue was discovered in Treasure Data Fluent Bit 1.7.1, erroneous parsing in flb_pack_msgpack_to_json_format leads to type confusion bug that interprets whatever is on the stack as msgpack maps and arrays, leading to use-after-free. This can be used by an attacker to craft a specially craft file and trick the victim opening it using the affect software, triggering use-after-free and execute arbitrary code on the target system.

• CWE-843Access of Resource Using Incompatible Type ('Type Confusion')The product allocates or initializes a resource such as a pointer, object, or variable using one type, but it later accesses that resource using a type that is incompatible with the original type.