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TI-2021-04473 Aliases CVE-2021-21374

Nimble fails to validate certificates due to insecure httpClient defaults

Priority LOW 37CWE-348Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
High
Impact type
Spoofing
Confidentiality · integrity · availability
Low · High · Low
Fix status
Fixed

Attack profile from CVSS 3.1 · CNA. Fix status from CNA. Impact type from CWE-295.

Summary

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.

Why it matters now

EPSS 0.0104 64th percentileScored 2026-11-07
Public exploit Yes 1 exploit referenceTagged by NVD
Fix Fixed security (nim-lang): 1.2.10, 1.4.4

SSVC decision points

Not available: CISA has not published SSVC decision points for this record.

Affected products

VendorProductAffected versionsFixed inStatusSource
nim-langsecuritybefore 1.2.10; 1.4.0 to before 1.4.41.2.10, 1.4.4Patch availableCNA
  • security Vendornim-lang Affected before 1.2.10; 1.4.0 to before 1.4.4 Fixed in 1.2.10, 1.4.4 Patch available CNA

CPE configurations NVD · 1

CPEVersionsRoleVendor
cpe:2.3:a:nim-lang:nim:*:*:*:*:*:*:*:*before 1.2.10; 1.4.0 to before 1.4.4Vulnerablenim-lang
  • cpe:2.3:a:nim-lang:nim:*:*:*:*:*:*:*:* Versions before 1.2.10; 1.4.0 to before 1.4.4 Vulnerable ·nim-lang

Remediation

  • Fix · CNA security (nim-lang) Fixed in 1.2.10, 1.4.4

Vendor assessments

Red Hat

Red Hat's page for this CVE →

Not affected: 1 product
  • Red Hat

Timeline

  1. 2026-10-02 Threatist record created from CVE-2021-21374

References

Exploit 1

Patch 1

Advisory 2

  • TI-2020-12364 In Nim 1.2.4, the standard library browsers mishandles the URL argument to… CVSS 3.1CRITICAL 9.8
  • TI-2020-12363 In Nim before 1.2.6, the standard library asyncftpclient lacks a check for whether a… CVSS 3.1CRITICAL 9.8
  • TI-2021-04471 Nimble arbitrary code execution for specially crafted package metadata CVSS 3.1HIGH 8.8
  • TI-2020-12366 In Nim 1.2.4, the standard library httpClient fails to properly validate the server… CVSS 3.1HIGH 7.5
  • TI-2021-04472 Nimble falls back to insecure http url when fetching packages CVSS 3.1HIGH 7.5
  • TI-2021-10206 Nim stdlib httpClient does not validate peer certificates by default CVSS 3.1HIGH 7.5
See all 8 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences