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Fencer Vulns
high 7.8

CVE-2021-46879 json

An issue was discovered in Treasure Data Fluent Bit 1.7.1, a wrong variable is used to get the msgpack data resulting in a heap overflow in…

published 2023-04-11 3 y ago modified 2026-09-08 2 mo ago also BIT-fluent-bit-2021-46879 , EUVD-2021-33529

cvss
7.8
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.4%
EPSS 0.4% chance of exploitation in 30 days, percentile 32%
public exploits
0
none known

Summary

An issue was discovered in Treasure Data Fluent Bit 1.7.1, a wrong variable is used to get the msgpack data resulting in a heap overflow in flb_msgpack_gelf_value_ext. An attacker can craft a malicious file and tick the victim to open the file with the software, triggering a heap overflow and execute arbitrary code on the target system.

Patch / fix

  • bitnami fluent-bit 1.7.2

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2021-46879 updated cvss 8.8

fluent-bit: heap overflow in flb_msgpack_gelf_value_ext

  • Red Hat All currently supported Red Hat products
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
Proof of concept is public
Automatable
no
Technical impact
total
Assessed
20 mo ago

Exploit prediction

0.38% chance of exploitation in the next 30 days, higher than 32% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • bugs.chromium.org https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=26851 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CISA ADP 3.1 7.8 CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
NVD 3.1 7.8 CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
CNA 3.1 7.8 CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
OSV 3.1 7.8 CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

Affected packages

ecosystem package affected fixed in
bitnami fluent-bit
>=1.7.1, <1.7.2
1.7.2

Classification

Weakness

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.