How severe is CVE-2015-4495?

CVE-2015-4495 has a CVSS score of 8.8/10, rated HIGH. Immediate patching is strongly recommended.

Which packages are affected by CVE-2015-4495?

Affected package information for CVE-2015-4495 is not yet fully mapped. Check the official advisory links for details.

How do I fix CVE-2015-4495?

No fixed release is recorded for CVE-2015-4495 yet. Track the upstream advisory, and apply the exposure-reduction steps below in the meantime.

How do I detect CVE-2015-4495 in my code and dependencies?

Identify every host running the affected component and compare the installed build against the fixed version below — for source-built or distro-packaged software the version string, not a lockfile, is the source of truth (`dpkg -l`, `rpm -q`, or the binary's own `--version`).

How do I mitigate CVE-2015-4495 if there is no patch (or I can't update yet)?

If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Is CVE-2015-4495 actively exploited in the wild?

Yes. There are 6 known exploit references for CVE-2015-4495, including 1 documented proof-of-concept exploit on Exploit-DB and 5 in-the-wild exploitations observed on GitHub and other sources. Treat this as actively exploitable and prioritize patching immediately. All exploit code should only be run in an isolated sandbox environment for research or authorized testing — never against production systems without explicit written authorization.

What is the EPSS score for CVE-2015-4495?

CVE-2015-4495 has an EPSS (Exploit Prediction Scoring System) score of 68.6%, placing it in the 99th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. A score above 50% indicates significantly elevated exploitation risk — immediate patching is strongly recommended.

Is CVE-2015-4495 in the CISA Known Exploited Vulnerabilities catalog?

Yes. CVE-2015-4495 (Mozilla Firefox Security Feature Bypass Vulnerability) was added to CISA's Known Exploited Vulnerabilities (KEV) catalog on 2022-05-25. CISA required all US federal civilian agencies to remediate this vulnerability by 2022-06-15. The required action was: Apply updates per vendor instructions. Being listed in the KEV catalog is the strongest possible confirmation of active exploitation — treat this as a critical priority.

What type of vulnerability is CVE-2015-4495?

CVE-2015-4495 is classified as CWE-346 (CWE-346). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2015-4495 published, and has it been updated?

CVE-2015-4495 was published on August 8, 2015 and was last updated on April 16, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🛡️

CISA KEV · ACTIVELY EXPLOITED

HIGH severity

CVE-2015-4495 — Red Hat

HIGH

CVE-2015-4495 is a high-severity (CVSS 8.8) CWE-346 vulnerability. It is in CISA's Known Exploited Vulnerabilities catalog (added 2022-05-25) — treat it as actively exploited and patch now. No vendor fix is recorded yet; mitigation options are listed below.

Published

Aug 8, 2015

Updated

Apr 16, 2026

Affected

15 products

Patched

See advisory

Exploits

6 known

Exploitation data as of Oct 22, 2026 · OSV.dev, NVD, CISA KEV, FIRST.org (EPSS)

Exploitation Status

Actively exploited in the wild

Confirmed by CISA's Known Exploited Vulnerabilities catalog on 2022-05-25. Federal agencies were required to remediate by 2022-06-15.
A successful exploit gives an attacker total control of the affected component, not partial access.

Exploitation and automatability from CISA (KEV catalog and SSVC triage) for CVE-2015-4495.

EPSS Exploitation Probability

via FIRST.org ↗

68.6%probability of exploitation in next 30 days

High Risk0.00%

Lower risk than most CVEs99th percentile — riskier than 99% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

CVE-2015-4495 by exploitation likelihood (EPSS) against impact (CVSS). In the shaded patch-first corner (EPSS 50%+, CVSS 7.0+).

Where this sits among everything scored

Of 394,415 CVEs with a current EPSS score, this one falls in the 50–90% band (highlighted). Counts from FIRST.org, log-scaled.

Description

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.

Affected Products

15 products · 49 configurations

ubuntu linuxcanonical

3 versions

12.0414.0415.04

Application

firefoxmozilla

≥ 38.0 && < 38.1.1

range

firefox osmozilla

< 2.2

range

opensuseopensuse

2 versions

13.113.2

solarisoracle

1 version

11.3

enterprise linux desktopredhat

3 versions

5.06.07.0

Exploits & PoCs

Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.

EDB-37772localmultiple

Mozilla Firefox < 39.03 - 'pdf.js' Same Origin Policy

by Tantaryu MING · Aug 15, 2015

Exploit-DB Source

Detection & mitigation playbook

Vulnerability

Detect
Identify every host running the affected component and compare the installed build against the fixed version below — for source-built or distro-packaged software the version string, not a lockfile, is the source of truth (`dpkg -l`, `rpm -q`, or the binary's own `--version`).
Remediation status
No fixed release is recorded for CVE-2015-4495 yet. Track the upstream advisory, and apply the exposure-reduction steps below in the meantime.
Mitigate without a patch
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Fixing This On Your OS

If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.

Red HatImportant

Product	Fixed in	Advisory
Red Hat Enterprise Linux 5	`firefox-0:38.1.1-1.el5_11`	RHSA-2015:1581

UbuntuHIGH

USN-2707-1Ubuntu

Frequently Asked Questions

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