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CVE-2021-31819

30
FAUCET Score

CVE-2021-31819 is a critical deserialization vulnerability (CVSS 9.8) affecting Halibut versions prior to 4.4.7, which could lead to remote code execution on systems that have established trust via certificate verification. This vulnerability is easily exploitable over the network with low attack complexity and no user interaction required, allowing for complete compromise of confidentiality, integrity, and availability. Despite its severity, there is no known active exploitation, public exploit code (Metasploit, Nuclei, ExploitDB), or significant community discussion or media coverage surrounding this CVE.

Impacted Technologies

VendorProductVersion(s)CPE
< 4.4.7CPE match
cpe:2.3:a:octopus:halibut:*:*:*:*:*:*:*:*

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
2.35%
Probability of exploitation in next 30 days
EPSS Percentile
82.0%
Percentile rank of EPSS score among Peer Group
As of 2026-07-28
Model: v2026.06.15
This CVE's current EPSS score of 0.0236 is in the 72nd percentile among its peer group of 36,897 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)

nugetpatch availablevia ghsa
Product: HalibutFixed in: 4.4.7

Vendor Advisories (1)

nugetGHSA-hpf7-4c2g-9chfcritical

Remote Code Execution in Halibut

Sep 23, 2021

References

advisories.octopus.com / adv/2021-08---Remote-Code-Execution-via-Deserialisation-in-the-Halibut-Protocol-%28CVE-2021-31819%29.2250309681.html