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CVE-2021-33586

18
FAUCET Score

CVE-2021-33586 is a medium-severity vulnerability affecting InspIRCd versions 3.8.0 through 3.9.x before 3.10.0, allowing any connected user to access recently deallocated memory through a malformed PONG message. With a CVSS score of 4.3, this low-complexity network attack requires low privileges and results in a low impact on confidentiality, with no impact on integrity or availability. There is currently no evidence of active exploitation, public exploit code (Metasploit, Nuclei, ExploitDB), or significant community discussion or media coverage.

Impacted Technologies

VendorProductVersion(s)CPE
>= 3.8.0, < 3.10.0CPE matchmatch criteria
cpe:2.3:a:inspircd:inspircd:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

4.3MEDIUM

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

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
LOW
Integrity Impact
NONE
Availability Impact
NONE
Exploitability Score
2.8
Impact Score
1.4
CvssVersion
3.1

Exploit Intelligence

EPSS Score
0.89%
Probability of exploitation in next 30 days
EPSS Percentile
55.7%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0089 is in the 68th percentile among its peer group of 21,957 CVEs.

Social Chatter

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

Media Mentions

No media coverage found for this CVE.

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

Remediation

Patch Available

Vendor Patches (1)

github_advisorypatch availablevia nvd_reference
View patch

References

docs.inspircd.org / security/2021-01
PatchVendor Advisory
github.com / inspircd/inspircd/commit/4350a11c663b0d75f8119743bffb7736d87abd4d
PatchThird Party Advisory
security.gentoo.org / glsa/202107-22
Third Party Advisory