CVE-2021-3499

A vulnerability was found in OVN Kubernetes in versions up to and including 0.3.0 where the Egress Firewall does not reliably apply firewall rules when there is multiple DNS rules. It could lead to potentially lose of confidentiality, integrity or availability of a service.

Published: 2021-06-02 Last update: 2024-11-21 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2021-3499 is rated Low Risk (34.2/100): CVSS Medium severity, with low exploitation likelihood (EPSS 0.14%). Monitor for updates and reassess as exploit intelligence or EPSS changes.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2021-3499

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2025-11-21 0.21% 0.14% -0.08%
2 2025-11-18 0.08% 0.21% +0.14%
3 2023-03-07 — 0.08% —

Full EPSS history (9 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2021-3499

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
5.6 3.1 MEDIUM
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:H)
Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:L)
Some sensitive info could get out, but not a total data dump.
Integrity (I:L)
Attackers could change some data, but it’s limited—not everything goes.
Availability (A:L)
Might cause slowdowns, glitches, or partial disruption—not a full brick.
 2.2 3.4 [email protected]
6.8 2.0 MEDIUM
AV:N/AC:M/Au:N/C:P/I:P/A:P Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:M)
Exploitation needs some favorable conditions, but not exceptional ones.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:P)
Partial confidentiality impact.
Integrity impact (I:P)
Partial integrity impact.
Availability impact (A:P)
Partial availability impact.
 8.6 6.4 [email protected]

Weakness enumeration for CVE-2021-3499

GitHub Security Advisory for CVE-2021-3499

OS Trackers for CVE-2021-3499

vendor priority summary link
redhat medium — https://access.redhat.com/security/cve/CVE-2021-3499

Affected software / configurations for CVE-2021-3499

Vendor Product Version Raw CPE
ovn ovn-kubernetes <= 0.3.0 cpe:2.3:a:ovn:ovn-kubernetes:*:*:*:*:*:*:*:*

References for CVE-2021-3499

URL Tags
https://bugzilla.redhat.com/show_bug.cgi?id=1949188 Issue Tracking Third Party Advisory
cvelogic Threat Intelligence