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Known exploited vulnerability · CISA KEV

CVE-2015-4495: Mozilla Firefox Security Feature Bypass Vulnerability

Moxilla Firefox allows remote attackers to bypass the Same Origin Policy to read arbitrary files or gain privileges.

CVE-2015-4495

Exploited in the wild. Fix this first.

CISA added it to the Known Exploited Vulnerabilities catalog on 2022-05-25: attackers are using it right now.

CISA KEV
Listed
Added 2022-05-25 · federal fix-by 2022-06-15
EPSS (30 days)
69%
Higher than 99.3% of CVEs · 2026-11-01
CVSS v3.1
8.8 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

What CISA says

Mozilla Firefox Security Feature Bypass Vulnerability

Apply updates per vendor instructions.

NVD description · published 2015-08-08

The PDF reader in Mozilla Firefox before 39.0.3, Firefox ESR 38.x before 38.1.1, and Firefox OS before 2.2 allows remote attackers to bypass the Same Origin Policy, and read arbitrary files or gain privileges, via vectors involving crafted JavaScript code and a native setter, as exploited in the wild in August 2015.

Full record on NVD

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How to check if you are exposed to CVE-2015-4495

  1. Find every Mozilla Firefox system you or your clients run, including ones exposed to the internet. Those come first: CISA only lists flaws attackers are already using.
  2. Compare each version with the fixed versions in the vendor advisory. Where no fix exists yet, apply the vendor’s mitigation or take the system off the internet.
  3. Run a credentialed vulnerability scan to catch the systems you missed, then check that the next scan no longer reports CVE-2015-4495.

US federal agencies had to fix this by 2022-06-15. Everyone else should treat that deadline as a guide: if it has passed, this is overdue.

Affected versions

Versions the National Vulnerability Database lists as vulnerable to CVE-2015-4495. Check the vendor advisory for the exact fixed builds before you sign anything off.

ProductVulnerable versions
Mozilla Firefoxbefore 39.0.3; from 38.0 before 38.1.1
Mozilla Firefox OSbefore 2.2
Oracle Solaris11.3
Canonical Ubuntu Linux12.04; 14.04; 15.04
Redhat Enterprise Linux Desktop5.0; 6.0; 7.0
Redhat Enterprise Linux EUS6.7; 7.1; 7.2; 7.3; 7.4; 7.5 and 2 more

NVD lists 9 more affected products; see the full record on NVD.

Timeline

  1. · Published in the National Vulnerability Database
  2. · Added to CISA's Known Exploited Vulnerabilities catalog, 2,482 days after it was published
  3. · Fix-by date for US federal agencies, passed 1,600 days ago

Weakness type

More exploited Mozilla vulnerabilities

CISA lists 13 exploited Mozilla vulnerabilities. The closest matches:

Keep going

Sources: CISA Known Exploited Vulnerabilities catalog (version 2026.10.30); EPSS data from FIRST.org; CVSS and descriptions from the NIST National Vulnerability Database. Checked 2026-11-01. This product uses the NVD API but is not endorsed or certified by the NVD.

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