How severe is CVE-2025-54366?

CVE-2025-54366 has a CVSS 3.x base score of 8.8, rated high severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2025-54366 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (58th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2025-54366?

CVE-2025-54366 affects Freescout. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2025-54366?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

Does CVE-2025-54366 have an EU (EUVD) identifier?

Yes. CVE-2025-54366 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-22772.

When was CVE-2025-54366 published?

CVE-2025-54366 was published on 2025-07-26 and last updated on 2026-06-17.

CVE-2025-54366

CVE-2025-54366 is a high-severity vulnerability in Freescout with a CVSS 3.x base score of 8.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-502.

Key facts

Severity: High (CVSS 3.x base score 8.8)
CVSS v4: 8.6
EPSS exploit prediction: 1% (58th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2025-22772
Weakness: CWE-502
Affected product: Freescout
Published: 2025-07-26
Last modified: 2026-06-17

Description

FreeScout is a lightweight free open source help desk and shared inbox built with PHP (Laravel framework). In versions 1.8.185 and below, there is a critical deserialization vulnerability in the /conversation/ajax endpoint that allows authenticated users with knowledge of the APP_KEY to achieve remote code execution. The vulnerability occurs when the application processes the attachments_all and attachments POST parameters through the insecure Helper::decrypt() function, which performs unsafe deserialization of user-controlled data without proper validation. This flaw enables attackers to create arbitrary objects and manipulate their properties, leading to complete compromise of the web application. This is fixed in version 1.8.186.

Frequently asked questions

What is CVE-2025-54366?: FreeScout is a lightweight free open source help desk and shared inbox built with PHP (Laravel framework). In versions 1.8.185 and below, there is a critical deserialization vulnerability in the /conversation/ajax endpoint that allows authenticated users with knowledge of the APP_KEY to achieve remote code execution. The vulnerability occurs when the application processes the attachments_all and attachments POST parameters through the insecure Helper::decrypt() function, which performs unsafe deserialization of user-controlled data without proper validation. This flaw enables attackers to create arbitrary objects and manipulate their properties, leading to complete compromise of the web application. This is fixed in version 1.8.186.
How severe is CVE-2025-54366?: CVE-2025-54366 has a CVSS 3.x base score of 8.8, rated high severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2025-54366 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (58th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2025-54366?: CVE-2025-54366 affects Freescout. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2025-54366?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
Does CVE-2025-54366 have an EU (EUVD) identifier?: Yes. CVE-2025-54366 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-22772.
When was CVE-2025-54366 published?: CVE-2025-54366 was published on 2025-07-26 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:freescout:freescout:*:*:*:*:*:*:*:*

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