CVE-2025-55030: Content-Disposition headers incorrectly ignored for some MIME types

Severity: medium (CVSS 6.1 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2025-08-19 · updated 2026-10-05
Weakness: CWE-640

Description

Firefox for iOS would not respect a Content-Disposition header of type Attachment and would incorrectly display the content inline rather than downloading, potentially allowing for XSS attacks. This vulnerability was fixed in Firefox for iOS 142.

Affected products

Mozilla Firefox: before 142.0 — fixed in 142.0

How to fix

Upgrade to a fixed version: Mozilla Firefox 142.0. Check the vendor advisory for mitigations.

References

https://bugzilla.mozilla.org/show_bug.cgi?id=1976304
https://www.mozilla.org/security/advisories/mfsa2025-68/

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