CVE-2024-45303Network attack vector

Stored XSS via unescaped event names

Published Sep 12, 2024 · Updated Sep 12, 2024

Stored cross-site scripting in Discourse Calendar before 0.5 allows remote attackers to execute script when a user views an event. Calendar and popover code place attacker-controlled event names into HTML content without escaping, allowing markup to execute in the viewer's browser. Exploitation requires a site with Discourse's default Content Security Policy disabled or weakened and a user to render the crafted event.

CVSS severity6.1
Medium
EPSS probability0.26%
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 Discourse Calendar before 0.5 allows remote attackers to execute script when a user views an event. Calendar and popover code place attacker-controlled event names into HTML content without escaping, allowing markup to execute in the viewer's browser. Exploitation requires a site with Discourse's default Content Security Policy disabled or weakened and a user to render the crafted event.

The record

CVE
CVE-2024-45303
Published
Sep 12, 2024
Updated
Sep 12, 2024
Vendor
Discourse
Product
Discourse Calendar
Classifications
CWE-79, T1189
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 12, 2024CVE publishedPublication date reported by the CVE source.
  2. Sep 12, 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=< 0.5

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Discourse · Discourse Calendarversion=< 0.5

Published CVSS scores

6.1GitHub, Inc.CVSS: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.

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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 exploitUnconfirmed

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1189Drive-by Compromise

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

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Your stack

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