CVE-2021-46878

Severity: high (CVSS 7.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.4% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2023-04-11 · updated 2026-06-17
Weakness: CWE-843

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.

Affected products

FluentBit Fluent Bit: 1.7.1

References

https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=27742
https://github.com/fluent/fluent-bit/pull/3115
https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=27742
https://github.com/fluent/fluent-bit/pull/3115

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