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CVE-2021-21374

25
FAUCET Score

CVE-2021-21374 affects Nimble, the package manager for the Nim programming language, in versions prior to 1.2.10 and 1.4.4. The vulnerability stems from insufficient SSL/TLS certificate verification during "nimble refresh" operations, allowing a Man-in-the-Middle (MitM) attacker to deliver malicious package lists. This high-severity vulnerability (CVSS 8.1) could lead to untrusted code execution if users install and utilize the compromised packages. There is currently no evidence of active exploitation, public exploit code (Metasploit, Nuclei, ExploitDB), or significant community discussion or media coverage surrounding this CVE.

Impacted Technologies

VendorProductVersion(s)CPE
< 1.2.10CPE matchmatch criteria
cpe:2.3:a:nim-lang:nim:*:*:*:*:*:*:*:*
>= 1.4.0, < 1.4.4CPE matchmatch criteria
cpe:2.3:a:nim-lang:nim:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

8.1HIGH

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

Attack Vector
NETWORK
Attack Complexity
HIGH
Privileges Required
NONE
User Interaction
NONE
Scope
CHANGED
Confidentiality Impact
LOW
Integrity Impact
HIGH
Availability Impact
LOW
Exploitability Score
2.2
Impact Score
5.3
CvssVersion
3.1

Exploit Intelligence

EPSS Score
1.04%
Probability of exploitation in next 30 days
EPSS Percentile
60.6%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0104 is in the 24th percentile among its peer group of 8,920 CVEs.

Social Chatter

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

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.1 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

consensys.net / diligence/vulnerabilities/nim-insecure-ssl-tls-defaults-remote-code-execution
ExploitThird Party Advisory
github.com / nim-lang/nimble/blob/master/changelog.markdown
Release NotesThird Party Advisory
github.com / nim-lang/Nim/pull/16940
PatchThird Party Advisory
github.com / nim-lang/security/security/advisories/GHSA-c2wm-v66h-xhxx
Third Party Advisory