CVE-2021-46872: An issue was discovered in Nim before 1.6.2

Q: How do I fix CVE-2021-46872?

nim: upgrade to 1.6.2; nimforum: upgrade to 2.2.0. Exact commands for each OS are on this page.

Q: Is CVE-2021-46872 being exploited?

CVE-2021-46872 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2021-46872 affect?

CVE-2021-46872 affects nim, nimforum. Severity is medium (CVSS 6.1). 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

Q: How urgent is CVE-2021-46872?

Priority 33/100. No elevated risk signals yet.

Routine

MEDIUM 6.1UPGRADEUPGRADE

CVE-2021-46872 is a medium-severity flaw (CVSS 6.1) affecting nim, nimforum. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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.)

Why this priority

No elevated risk signals yet

A fixed release or distro patch exists.

Risk facts

CVSS score	6.1 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	Required
EPSS exploit chance	0.6% (top 53%)
CISA exploited list	No
Weakness	CWE-79
Published	2023-01-13
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: nim-lang

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2023-01-13 06:15 UTCPublished CVE record published
2026-06-17 04:15 UTCUpdated Record last modified

nim-lang nim UPGRADE

Affected: < 1.6.2

Fixed in: 1.6.2

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy nim || rpm -q nim || nim --version

2. UPGRADE to 1.6.2 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade nim

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade nim

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

nim-lang nimforum UPGRADE

Affected: < 2.2.0

Fixed in: 2.2.0

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy nimforum || rpm -q nimforum || nimforum --version

2. UPGRADE to 2.2.0 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade nimforum

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade nimforum

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2021-46872?

nim: upgrade to 1.6.2; nimforum: upgrade to 2.2.0. Exact commands for each OS are on this page.

Is CVE-2021-46872 being exploited?

CVE-2021-46872 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2021-46872 affect?

CVE-2021-46872 affects nim, nimforum. Severity is medium (CVSS 6.1). 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

How urgent is CVE-2021-46872?

Priority 33/100. No elevated risk signals yet.

References

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