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CVE-2021-21374

Nimble fails to validate certificates due to insecure httpClient defaults

HIGH
8.1
CVSS Score
Published: March 26, 2021 at 09:25 PM UTC
Updated: June 17, 2026 at 03:35 AM UTC
2 products affected across 1 vendorNimLang Nim

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Severity
HIGH8.1
Exploit prediction
EPSS 1%

Description

Nimble is a package manager for the Nim programming language. In Nim release versions before versions 1.2.10 and 1.4.4, "nimble refresh" fetches a list of Nimble packages over HTTPS without full verification of the SSL/TLS certificate due to the default setting of httpClient. An attacker able to perform MitM can deliver a modified package list containing malicious software packages. If the packages are installed and used the attack escalates to untrusted code execution.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Nim· Nim Lang
95%
v < 1.2.101.4.0 ≤ v < 1.4.4
Affected range stops below 1.2.10, so it looks safe — our inference, not a vendor statement
Affected range stops below 1.4.4, so it looks safe — our inference, not a vendor statement
Lang Nim· Nim Lang
60%
v < 1.2.10v < 1.4.4
Affected range stops below 1.2.10, so it looks safe — our inference, not a vendor statement
Affected range stops below 1.4.4, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

Patch and advisory references

References (4)

x_refsource_MISCExploitThird Party Advisory
Source: [email protected]
https://consensys.net/diligence/vulnerabilities/nim-insecure-ssl-tls-defaults-remote-code-execution/
x_refsource_MISCPatchThird Party Advisory
Source: [email protected]
https://github.com/nim-lang/Nim/pull/16940
x_refsource_MISCRelease NotesThird Party Advisory
Source: [email protected]
https://github.com/nim-lang/nimble/blob/master/changelog.markdown#0130
x_refsource_CONFIRMThird Party Advisory
Source: [email protected]
https://github.com/nim-lang/security/security/advisories/GHSA-c2wm-v66h-xhxx

CVSS

8.1HIGHGitHub_M
Attack Vector
NETWORK
Complexity
HIGH
Privileges
NONE
User Interaction
NONE
Scope
CHANGED
Confidentiality
LOW
Integrity
HIGH
Availability
LOW
Vector?

Quick Info

StatusMODIFIED
CWE
CWE-348CWE-349CWE-599CWE-295

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