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CVE-2021-3466

35
FAUCET Score

CVE-2021-3466 is a critical buffer overflow vulnerability in libmicrohttpd version 0.9.70, affecting products like Fedora and Red Hat Enterprise Linux. A missing bounds check in the post_process_urlencoded function allows remote attackers to write arbitrary data. This flaw carries a CVSS score of 9.8, indicating high impacts on confidentiality, integrity, and availability, with no user interaction required. While there is no known active exploitation or public exploit code, the vulnerability has garnered significant community discussion, with 10 mentions across various platforms.

Impacted Technologies

VendorProductVersion(s)CPE
0.9.70CPE matchmatch criteria
cpe:2.3:a:gnu:libmicrohttpd:0.9.70:*:*:*:*:*:*:*
6.0CPE matchmatch criteria
cpe:2.3:o:redhat:enterprise_linux:6.0:*:*:*:*:*:*:*
7.0CPE matchmatch criteria
cpe:2.3:o:redhat:enterprise_linux:7.0:*:*:*:*:*:*:*
8.0CPE matchmatch criteria
cpe:2.3:o:redhat:enterprise_linux:8.0:*:*:*:*:*:*:*
32CPE matchmatch criteria
cpe:2.3:o:fedoraproject:fedora:32:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

9.8CRITICAL

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

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
Exploitability Score
3.9
Impact Score
5.9
CvssVersion
3.1

Exploit Intelligence

EPSS Score
8.74%
Probability of exploitation in next 30 days
EPSS Percentile
94.6%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0874 is in the 90th percentile among its peer group of 36,835 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.1 Reddit, 0.3 Bluesky, 0.3 Mastodon, and 2.4 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 (1)

redhatpatch availablevia nvd_reference
View patch

Vendor Advisories (1)

redhatCVE-2021-3466Important

libmicrohttpd: Buffer overflow issue in URL parser in the post_process_urlencoded function

Mar 15, 2021

References

bugzilla.redhat.com / show_bug.cgi
Issue TrackingPatchThird Party Advisory
lists.fedoraproject.org / archives/list/package-announce%40lists.fedoraproject.org/message/4334XJNDJPYQNFE6S3S2KUJJ7TMHYCWL
lists.fedoraproject.org / archives/list/package-announce%40lists.fedoraproject.org/message/75HDMREKITMGPGE62NP7KE62ZJVLETXN
lists.fedoraproject.org / archives/list/package-announce%40lists.fedoraproject.org/message/K5NEPVGP3L2CZHLZ4UB44PEILHKPDBOG
security.gentoo.org / glsa/202311-08