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CVE-2021-29495

23
FAUCET Score

CVE-2021-29495 is a high-severity vulnerability affecting the Nim programming language's standard library prior to version 1.4.2, where httpClient SSL/TLS certificate verification was disabled by default. This flaw (CWE-295) allows for man-in-the-middle attacks, potentially leading to data interception or modification due to a lack of proper certificate validation. While the CVSS score is 7.5 (High), indicating a critical security risk, there is currently no evidence of active exploitation, public exploit code, or significant community discussion surrounding this vulnerability. Users are advised to upgrade to Nim 1.4.2 or implement the documented workaround of setting "verifyMode = CVerifyPeer".

Impacted Technologies

VendorProductVersion(s)CPE
< 1.4.2CPE matchmatch criteria
cpe:2.3:a:nim-lang:nim:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

5.9MEDIUM

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

Attack Vector
NETWORK
Attack Complexity
HIGH
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
NONE
Integrity Impact
HIGH
Availability Impact
NONE
Exploitability Score
2.2
Impact Score
3.6
CvssVersion
3.1

Exploit Intelligence

EPSS Score
0.49%
Probability of exploitation in next 30 days
EPSS Percentile
39.4%
Percentile rank of EPSS score among Peer Group
As of 2026-07-28
Model: v2026.06.15
This CVE's current EPSS score of 0.0049 is in the 17th percentile among its peer group of 51,553 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.1 Mastodon, and 0.4 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

Remediation records are not available for this CVE.

References

github.com / nim-lang/security/security/advisories/GHSA-9vqv-2jj9-7mqr
Third Party Advisory