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Fencer Vulns
high 8.3

CVE-2021-21372 json

Nimble arbitrary code execution for specially crafted package metadata

published 2021-03-26 5 y ago modified 2026-06-17 4 mo ago also EUVD-2021-8682

cvss
8.3
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
3.6%
EPSS 3.6% chance of exploitation in 30 days, percentile 89%
public exploits
0
none known

Summary

Nimble is a package manager for the Nim programming language. In Nim release version before versions 1.2.10 and 1.4.4, Nimble doCmd is used in different places and can be leveraged to execute arbitrary commands. An attacker can craft a malicious entry in the packages.json package list to trigger code execution.

Patch / fix

  • nim-lang nim 1.2.10, 1.4.4
  • nim Debian 14, Debian 12 1.4.6+really1.4.2-1

debian advisories DEBIAN-CVE-2021-21372

  • nim openSUSE Tumbleweed 1.2.12-1.7
  • nim Package Hub 15 SP4, openSUSE Leap 15.4 1.6.6-bp154.2.3.1
  • nim Package Hub 15 SP3, openSUSE Leap 15.3 1.6.6-bp153.2.3.1
  • nim Package Hub 15 SP2 1.2.12-bp152.4.3.1
  • nim openSUSE Leap 15.2 1.2.12-lp152.2.3.1

opensuse advisories openSUSE-SU-2024:11093-1openSUSE-SU-2022:10101-1openSUSE-SU-2022:10095-1openSUSE-SU-2021:0628-1openSUSE-SU-2021:0618-1

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2021-21372 updated cvss 8.8

nim: doCmd can be leveraged to execute arbitrary commands

  • Red Hat All currently supported Red Hat products
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

3.62% chance of exploitation in the next 30 days, higher than 89% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • consensys.net https://consensys.net/diligence/vulnerabilities/nim-insecure-ssl-tls-defaults-remote-code-execution/ referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 8.3 CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:H/I:H/A:H
NVD 3.1 8.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
NVD 2.0 6.8 AV:N/AC:M/Au:N/C:P/I:P/A:P

Affected products

  • nim-lang security

Classification

Weakness
  • CWE-20 Improper Input Validation
  • CWE-74 Improper Neutralization of Special Elements in Output Used by a Downstream Component
  • CWE-78 Improper Neutralization of Special Elements used in an OS Command

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.