CVE-2015-4495
CVE-2015-4495 is a security flaw in Mozilla Firefox, Mozilla’s web browser. Attackers can read files on Mozilla Firefox that should be out of reach. The US Cybersecurity and Infrastructure Security Agency (CISA) added it to its catalog of flaws known to be used in attacks on 25 May 2022.[1]
Mozilla Firefox is in things households have, such as phones, computers, browsers and everyday apps, so the fix matters at home as much as at work. Mozilla has published a fix or advice.
Description
CISA calls it a security feature bypass in Mozilla Firefox. In its words: “Moxilla Firefox allows remote attackers to bypass the Same Origin Policy to read arbitrary files or gain privileges.”[1]
The CVE record adds: “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.”[2]
The underlying weakness is information exposure (CWE-200), in MITRE’s list of common software weaknesses.
It scores 8.8 out of 10 on the Common Vulnerability Scoring System, which rates it high, scored by NVD using CVSS 3.1.[2]
Affected versions
NVD’s record doesn’t list version ranges for it; Mozilla’s advisory has them[3]. CISA names the product as Mozilla Firefox.
Every device with Mozilla Firefox needs the update.
Exploitation
CISA added it to its catalog of known exploited vulnerabilities on 25 May 2022, 2,482 days after it was made public. CISA lists a flaw only when it has reliable evidence of it being exploited, and gave US federal agencies until 15 Jun 2022 to fix it.[1]
FIRST’s Exploit Prediction Scoring System, which estimates how likely a flaw is to be used in attacks in the next 30 days from what it sees across the internet, puts it at 69%. That’s in the top 1% of the flaws it scores.[4]
CISA assesses it as not automatable: each attack takes some work.
CISA doesn’t say who was attacked, or how.
Fix
Mozilla has published a fix or advice.[3] CISA’s required action: “Apply updates per vendor instructions.”[1]
- Update Mozilla Firefox now.Install the latest update from Mozilla on every device that has it, and restart when asked. Then turn on automatic updates, so the next fix arrives on its own.
- If there’s no update, stop using it.CISA’s advice when a flaw being used in attacks has no fix is to stop using the product until it does.
Timeline
| Date | Event |
|---|---|
| The flaw is made public in the National Vulnerability Database, with a severity score of 8.8.[2] | |
| CISA adds it to its catalog of flaws known to be used in attacks.[1] | |
| CISA’s deadline for US government agencies to fix it.[1] | |
| FIRST puts the odds of it being used in attacks in the next 30 days at 69%.[4] |
See also
Other Mozilla Firefox flaws
- CVE-2024-9680: use-after-free ·
- CVE-2022-26486: use-after-free ·
- CVE-2022-26485: use-after-free ·
- CVE-2013-1675: information disclosure ·
Other Mozilla flaws
- CVE-2010-3765, Mozilla products: remote code execution ·
- CVE-2016-9079, Mozilla Firefox, Firefox ESR, and Thunderbird: use-after-free ·
- CVE-2019-11708, Mozilla Firefox and Thunderbird: sandbox escape ·
- CVE-2019-11707, Mozilla Firefox and Thunderbird: type confusion ·
- CVE-2013-1690, Mozilla Firefox and Thunderbird: denial-of-service ·
Other information exposure flaws
- CVE-2025-68686, Fortinet FortiOS: exposure of sensitive information to an unauthorized actor ·
- CVE-2026-20133, Cisco Catalyst SD-WAN Manager: exposure of sensitive information to an unauthorized actor ·
- CVE-2025-31125, Vitejs: improper access control ·
- CVE-2026-20805, Microsoft Windows: information disclosure ·
- CVE-2021-41277, Metabase: geoJSON API local file inclusion ·
Added the same day
- CVE-2019-3010, Oracle Solaris: privilege escalation ·
- CVE-2016-7256, Microsoft Windows: open type font remote code execution ·
- CVE-2016-3393, Microsoft Windows: graphics device interface (GDI) remote code execution ·
- CVE-2016-1010, Adobe Flash Player and AIR: integer overflow ·
- CVE-2016-0984, Adobe Flash Player and AIR: use-after-free ·
Every Mozilla flaw on CISA’s list · Everything added in May 2022
References
- ^ Cybersecurity and Infrastructure Security Agency. “Mozilla Firefox Security Feature Bypass Vulnerability”. Known Exploited Vulnerabilities Catalog, added 25 May 2022.
- ^ National Institute of Standards and Technology. “CVE-2015-4495 Detail”. National Vulnerability Database, published 8 Aug 2015.
- ^ Mozilla. Advisories and fixes: blog.mozilla.org.
- ^ FIRST. “Exploit Prediction Scoring System”. EPSS 0.686, percentile 99.3, 31 Oct 2026.
- CVE Program. “CVE-2015-4495”. The official CVE record.
This article is built from CISA’s catalog (version 2026.10.30), NVD’s record and FIRST’s scores, kept in HARD’s database and checked every morning. The plain English is HARD’s.