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CVE-2021-46879

25
FAUCET Score

CVE-2021-46879 describes a heap overflow vulnerability in Treasure Data Fluent Bit version 1.7.1, specifically within the flb_msgpack_gelf_value_ext function due to an incorrect variable usage when processing msgpack data. This vulnerability carries a CVSS score of 7.8 (High), indicating that a local attacker could trigger arbitrary code execution if a victim is enticed into opening a specially crafted file. Currently, there is no evidence of active exploitation, publicly available exploit code (Metasploit, Nuclei, ExploitDB), or significant community discussion or media coverage surrounding this CVE.

Impacted Technologies

VendorProductVersion(s)CPE
1.7.1CPE matchmatch criteria
cpe:2.3:a:treasuredata:fluent_bit:1.7.1:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

7.8HIGH

CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

Attack Vector
LOCAL
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
REQUIRED
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
Exploitability Score
1.8
Impact Score
5.9
CvssVersion
3.1

Exploit Intelligence

EPSS Score
0.38%
Probability of exploitation in next 30 days
EPSS Percentile
30.7%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0038 is in the 29th percentile among its peer group of 11,616 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.1 Reddit, 0.1 Bluesky, 0.0 Mastodon, and 0.2 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.3 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (5)

github_advisorypatch availablevia nvd_reference
View patch
microsoftpatch availablevia msrc
Product: cm1 fluent-bit 1.5.2-3 on CBL Mariner 1.0Fixed in: 1.5.2-3
microsoftpatch availablevia msrc
Product: CBL Mariner 1.0 x64Fixed in: 1.5.2-3
microsoftpatch availablevia msrc
Product: CBL Mariner 1.0 ARMFixed in: 1.5.2-3
microsoftpatch availablevia msrc
Product: 18492-16820Fixed in: 1.5.2-3

Vendor Advisories (2)

microsoft2023-May/CVE-2021-46879

CVE-2021-46879

May 9, 2023
microsoft2023-Apr/CVE-2021-46879Important

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.

Apr 11, 2023

References

bugs.chromium.org / p/oss-fuzz/issues/detail
ExploitIssue TrackingPatchThird Party Advisory
github.com / fluent/fluent-bit/pull/3100
Patch