What’s Vulnerable › Vulnerabilities

CVE-2021-46872

• Severity: medium (CVSS 6.1 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.6% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2023-01-13 · updated 2026-06-17
• Weakness: CWE-79

Description

An issue was discovered in Nim before 1.6.2. The RST module of the Nim language stdlib, as used in NimForum and other products, permits the javascript: URI scheme and thus can lead to XSS in some applications. (Nim versions 1.6.2 and later are fixed; there may be backports of the fix to some earlier versions. NimForum 2.2.0 is fixed.)

Affected products

• nim-lang Nim: before 1.6.2 — fixed in 1.6.2
• nim-lang Nimforum: before 2.2.0 — fixed in 2.2.0

How to fix

Upgrade to a fixed version: nim-lang Nim 1.6.2; nim-lang Nimforum 2.2.0. Check the vendor advisory for mitigations.

References

• https://forum.nim-lang.org/t/8852
• https://github.com/nim-lang/Nim/commit/46275126b89218e64844eee169e8ced05dd0e2d7
• https://github.com/nim-lang/Nim/compare/v1.6.0...v1.6.2
• https://github.com/nim-lang/Nim/pull/19134
• https://github.com/nim-lang/nimforum
• https://forum.nim-lang.org/t/8852
• https://github.com/nim-lang/Nim/commit/46275126b89218e64844eee169e8ced05dd0e2d7
• https://github.com/nim-lang/Nim/compare/v1.6.0...v1.6.2
• https://github.com/nim-lang/Nim/pull/19134
• https://github.com/nim-lang/nimforum

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