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Fencer Vulns
medium 5.9

CVE-2021-29495 json

Nim stdlib httpClient does not validate peer certificates by default

published 2021-05-07 5 y ago modified 2026-06-17 4 mo ago also EUVD-2021-16092

cvss
5.9
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.5%
EPSS 0.5% chance of exploitation in 30 days, percentile 42%
public exploits
0
none known

Summary

Nim is a statically typed compiled systems programming language. In Nim standard library before 1.4.2, httpClient SSL/TLS certificate verification was disabled by default. Users can upgrade to version 1.4.2 to receive a patch or, as a workaround, set "verifyMode = CVerifyPeer" as documented.

Patch / fix

  • nim-lang nim 1.4.2
  • nim Debian 14, Debian 12 1.4.2-1

debian advisories DEBIAN-CVE-2021-29495

  • nim openSUSE Tumbleweed 1.6.6-3.1
  • 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

opensuse advisories openSUSE-SU-2024:12253-1openSUSE-SU-2022:10101-1openSUSE-SU-2022:10095-1

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-2021-29495 updated cvss 5.9

nim: stdlib httpClient does not validate peer certificates by default

  • 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

0.49% chance of exploitation in the next 30 days, higher than 42% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 5.9 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N
NVD 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
NVD 2.0 5.0 AV:N/AC:L/Au:N/C:N/I:P/A:N

Affected products

  • nim-lang security

Classification

Weakness
  • CWE-295 Improper Certificate Validation

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.