CVE-2026-53900

Cookie injection was possible when opening a PDF link

CVSS 4.3 MEDIUMEPSS 0.1%CWE-345 CWE-384

Vexday Risk Score

13Low

SSVC decision (CISA)

Track

No exploitation signal → monitor

CVSS 4.3EPSS 0.1%KEV nãoPoC —Nuclei —Metasploit —Patch —

Lifecycle

16 Jun 2026Published on NVD

Recommendation: Monitor — no exploitation signal at the moment.

Firefox for iOS preserved cookies set on the initial PDF request across cross-origin HTTP redirects in TemporaryDocument, allowing a malicious site to inject arbitrary cookies into requests to an unrelated target domain. This vulnerability was fixed in Firefox for iOS 152.0.

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:N

Affected products

Mozilla · Firefox for iOS

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References

https://bugzilla.mozilla.org/show_bug.cgi?id=2043204 https://www.mozilla.org/security/advisories/mfsa2026-56/