CVE-2025-39404Network attack vector

Phishing redirect via unvalidated Mastodon AMP URL

Published Apr 24, 2025 · Updated Apr 28, 2026

Open redirect in Sassy Social Share 3.3.73 and earlier allows remote attackers to send users to malicious sites through Mastodon sharing on AMP pages. The Mastodon AMP handler decodes the heateor_mastodon_share query value and assigns the resulting URL to location.href without restricting its destination. Exploitation requires a user to open a crafted AMP sharing link and submit the Mastodon dialog, enabling a phishing redirect from a trusted site.

CVSS severity4.7
Medium
EPSS probability0.31%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Open redirect in Sassy Social Share 3.3.73 and earlier allows remote attackers to send users to malicious sites through Mastodon sharing on AMP pages. The Mastodon AMP handler decodes the heateor_mastodon_share query value and assigns the resulting URL to location.href without restricting its destination. Exploitation requires a user to open a crafted AMP sharing link and submit the Mastodon dialog, enabling a phishing redirect from a trusted site.

The record

CVE
CVE-2025-39404
Published
Apr 24, 2025
Updated
Apr 28, 2026
Vendor
Heateor Support
Product
Sassy Social Share
Classifications
CWE-601, T1204.001
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 24, 2025CVE publishedPublication date reported by the CVE source.
  2. Apr 28, 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 <=3.3.73 changes=[{"at":"3.3.74","status":"unaffected"}]

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Heateor Support · Sassy Social Shareversion=0 <=3.3.73 changes=[{"at":"3.3.74","status":"unaffected"}]

Published CVSS scores

4.7Patchstack OÜCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:N/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-601URL Redirection to Untrusted Site ('Open Redirect')
T1204.001User Execution: Malicious Link

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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