CVE-2026-87812Public exploitNetwork attack vector

Stored XSS via unescaped Bazaar iconURL

Published Sep 9, 2026 · Updated Sep 10, 2026

Stored XSS in SiYuan before 3.8.2 allows remote attackers to execute JavaScript when a user views a malicious Bazaar package card. app/src/config/bazaar.ts interpolates package iconURL metadata into an img src attribute without attribute escaping or scheme validation. A malicious or compromised marketplace metadata source and a viewed listing are required; the script runs in the authenticated SiYuan origin and can issue same-origin API requests or manipulate application state.

CVSS severity7.4
High
EPSS probability0.20%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Stored XSS in SiYuan before 3.8.2 allows remote attackers to execute JavaScript when a user views a malicious Bazaar package card. app/src/config/bazaar.ts interpolates package iconURL metadata into an img src attribute without attribute escaping or scheme validation. A malicious or compromised marketplace metadata source and a viewed listing are required; the script runs in the authenticated SiYuan origin and can issue same-origin API requests or manipulate application state.

The record

CVE
CVE-2026-87812
Published
Sep 9, 2026
Updated
Sep 10, 2026
Vendor
SiYuan Note
Product
SiYuan
Classifications
CWE-79, T1203
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 9, 2026CVE publishedPublication date reported by the CVE source.
  2. Sep 10, 2026Record 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=0 <3.8.2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

SiYuan Note · SiYuanversion=0 <3.8.2

Published CVSS scores

9.0GitHub Security AdvisoryCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:H
6.8VulnCheckCVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:N
7.4VulnCheckCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:A/VC:H/VI:H/VA:N/SC:N/SI:N/SA: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.

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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')
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

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Your stack

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