CVE-2021-4274Public exploitNetwork attack vector

Browser script execution via unescaped query value

Published Dec 21, 2022 · Updated Apr 14, 2025

Cross-site scripting in Sileht BIRD-LG allows remote attackers to execute browser script through a crafted query string. The layout.html template inserts session.request_args into a JavaScript string while marking the value safe, so quotes in the q parameter escape the string without HTML encoding. Execution requires a user to open the crafted route or enter the payload, and the script runs in that user's BIRD-LG origin.

CVSS severity3.5
Low
EPSS probability0.50%
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 Sileht BIRD-LG allows remote attackers to execute browser script through a crafted query string. The layout.html template inserts session.request_args into a JavaScript string while marking the value safe, so quotes in the q parameter escape the string without HTML encoding. Execution requires a user to open the crafted route or enter the payload, and the script runs in that user's BIRD-LG origin.

The record

CVE
CVE-2021-4274
Published
Dec 21, 2022
Updated
Apr 14, 2025
Vendor
Sileht
Product
BIRD-LG
Classifications
CWE-79, CWE-707, T1203
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Dec 21, 2022CVE publishedPublication date reported by the CVE source.
  2. Apr 14, 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?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=n/a

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Sileht · BIRD-LGversion=n/a

Published CVSS scores

3.5VulDBCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:L/A:N
6.1NVDCVSS: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 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
CWE-707Improper Neutralization
T1203Exploitation for Client Execution

Public exploit references

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