SOC status:Duty analyst on shift

UK Cyber Defence
VulnerabilityModified

CVE-2017-7791

On pages containing an iframe, the "data:" protocol can be used to create a modal alert that will render over arbitrary domains following page navigation, spoofing of the origin of the modal alert from the iframe content.

MEDIUM 5.3EPSS 1.80%

Does this matter?

Lower severity and a low EPSS score (1.80%). Track it; it rarely justifies an emergency change on its own.

Description

On pages containing an iframe, the "data:" protocol can be used to create a modal alert that will render over arbitrary domains following page navigation, spoofing of the origin of the modal alert from the iframe content. This vulnerability affects Thunderbird < 52.3, Firefox ESR < 52.3, and Firefox < 55.

CVSS 3.0
5.3 MEDIUMCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
EPSS
1.80% probability · 78th percentile
Public exploits
None in Exploit-DB
CISA KEV
Not listed
Weakness
CWE-20
Affected
debian/debian linux · redhat/enterprise linux · redhat/enterprise linux desktop · redhat/enterprise linux server · redhat/enterprise linux server aus · redhat/enterprise linux server eus · redhat/enterprise linux workstation · mozilla/thunderbird · mozilla/firefox
Source
security@mozilla.org
EPSS trend
0%3%5%27 October 2026: 1.80%27 October 202627 October 2026

EPSS 1.8% since 27 October 2026; no change recorded yet. Points are recorded when the score first appears and whenever it moves by a percentage point or more.

References

Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.