Nim stdlib httpClient does not validate peer certificates by default
Priority LOW 33CWE-295Published · Updated
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Impact type
- Spoofing
- Confidentiality · integrity · availability
- None · High · None
- Fix status
- Fixed
Attack profile from CVSS 3.1 · NVD. Fix status from CNA. Impact type from CWE-295.
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.
Why it matters now
EPSS 0.00491 42nd percentileScored 2026-11-07
Fix Fixed security (nim-lang): 1.4.2
SSVC decision points
Not available: CISA has not published SSVC decision points for this record.
Affected products
Remediation
- Fix · CNA security (nim-lang) Fixed in 1.4.2
Vendor assessments
Timeline
- 2026-10-02 Threatist record created from CVE-2021-29495
References
More nim-lang Nim vulnerabilities
- 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-2021-04473 Nimble fails to validate certificates due to insecure httpClient defaults CVSS 3.1HIGH 8.1
- 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
Sources
- CVE-2021-29495 · CVE Program
- CVE-2021-29495 · NVD
- FIRST EPSS
- CVE-2021-29495 · Red Hat security data · CC BY 4.0
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