CVE-2021-46872Network attack vector

Cross-site scripting via unfiltered RST link schemes

Published Jan 13, 2023 · Updated Apr 7, 2025

Cross-site scripting in Nim's RST module before 1.6.2 allows remote attackers to execute script through a crafted link viewed by a user. The HTML renderer's renderHyperlink and image-target paths emitted non-HTTP URI schemes into href values without validating the protocol, allowing javascript links to survive RST conversion. Exploitation requires an application such as NimForum to render attacker-controlled RST and a user to follow the generated link, exposing browser-accessible data and actions.

CVSS severity6.1
Medium
EPSS probability0.54%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Cross-site scripting in Nim's RST module before 1.6.2 allows remote attackers to execute script through a crafted link viewed by a user. The HTML renderer's renderHyperlink and image-target paths emitted non-HTTP URI schemes into href values without validating the protocol, allowing javascript links to survive RST conversion. Exploitation requires an application such as NimForum to render attacker-controlled RST and a user to follow the generated link, exposing browser-accessible data and actions.

The record

CVE
CVE-2021-46872
Published
Jan 13, 2023
Updated
Apr 7, 2025
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-79, T1203
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jan 13, 2023CVE publishedPublication date reported by the CVE source.
  2. Apr 7, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

6.1CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1203Exploitation for Client Execution

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo