CVE-2026-4494Public exploitNetwork attack vector

Browser script execution via unneutralized topic content

Published Mar 20, 2026 · Updated Mar 20, 2026

Stored cross-site scripting in atjiu pybbs 6.0.0 allows remote authenticated users to execute script in a viewer's browser. TopicApiController.create passes request-body title, content, and tag values to topicService.insert without HTML neutralization, causing attacker-supplied markup to be stored and returned with forum topics. An activated forum account is required to create the topic, and a victim must view the crafted content; the documented consequence is unauthorized modification in the browser context.

CVSS severity3.5
Low
EPSS probability0.29%
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 atjiu pybbs 6.0.0 allows remote authenticated users to execute script in a viewer's browser. TopicApiController.create passes request-body title, content, and tag values to topicService.insert without HTML neutralization, causing attacker-supplied markup to be stored and returned with forum topics. An activated forum account is required to create the topic, and a victim must view the crafted content; the documented consequence is unauthorized modification in the browser context.

The record

CVE
CVE-2026-4494
Published
Mar 20, 2026
Updated
Mar 20, 2026
Vendor
atjiu
Product
pybbs
Classifications
CWE-79, CWE-94, T1059.007
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Mar 20, 2026CVE publishedPublication date reported by the CVE source.
  2. Mar 20, 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=6.0.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

atjiu · pybbsversion=6.0.0

Published CVSS scores

4.0VulDBAV:N/AC:L/Au:S/C:N/I:P/A:N
2.0VulDBCVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:P
3.5VulDBCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/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
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
CWE-94Improper Control of Generation of Code ('Code Injection')
T1059.007Command and Scripting Interpreter: JavaScript

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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