CVE-2021-3853Network attack vector

Script execution via unescaped conversation preview HTML

Published Jan 17, 2022 · Updated Aug 3, 2024

Stored cross-site scripting in Chaskiq before 0.9.8 allows remote attackers to execute script in a user's browser via crafted message HTML. ConversationItemList passes lastMessage.message.htmlContent into the conversation preview without first escaping HTML; the patch adds escapeHTML before sanitization. Exploitation requires storing crafted message content and a victim viewing the affected conversation list, with consequences limited to the victim's browser context.

CVSS severity6.1
Medium
EPSS probability0.62%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Stored cross-site scripting in Chaskiq before 0.9.8 allows remote attackers to execute script in a user's browser via crafted message HTML. ConversationItemList passes lastMessage.message.htmlContent into the conversation preview without first escaping HTML; the patch adds escapeHTML before sanitization. Exploitation requires storing crafted message content and a victim viewing the affected conversation list, with consequences limited to the victim's browser context.

The record

CVE
CVE-2021-3853
Published
Jan 17, 2022
Updated
Aug 3, 2024
Vendor
Chaskiq
Product
Chaskiq
Classifications
CWE-79
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jan 17, 2022CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

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

  1. Affected versionversion=unspecified <0.9.8

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Chaskiq · Chaskiqversion=unspecified <0.9.8

Published CVSS scores

6.5huntr.devCVSS:3.0/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:L
6.1NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
4.3NIST NVDAV:N/AC:M/Au:N/C:N/I:P/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 exploitUnconfirmed

Weakness, pattern, technique

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

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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