What is the CVSS score of CVE-2023-6209?

CVE-2023-6209 has a CVSS 3.1 base score of 6.5 (Medium). CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N. EPSS exploitation probability: 1.4%.

Firefox CVE-2023-6209

MEDIUM

Path Traversal (CWE-22)

2023-11-21 security@mozilla.org

Path Traversal Debian Mozilla Debian Linux Firefox Thunderbird Firefox Esr

6.5

CVSS 3.1 · NVD

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Vulnerability Assessment

Weakness	CWE CWE-22 OWASP Top 10:2025 A01:2025 - Broken Access Control ASVS 5.0 V5 - File Handling Path canonicalization, traversal prevention MITRE ATT&CK 2 techniques across 2 tactics: Discovery, Collection The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up. Sign in to read
Impact	CVSS score of 6.5 (MEDIUM). Attack characteristics: network attack vector, low complexity, no privileges required, user interaction required.
Exploit ScenarioDerived	A remote attacker could access files and directories outside the intended path by sending crafted requests to the affected application. No authentication is required to exploit this vulnerability.

This Month Plan within 30 days. Why: MEDIUM severity (CVSS 4.0-6.9).

No patch listed yet 1.4% exploitation probability (EPSS)

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AnalysisAI

Relative URLs starting with three slashes were incorrectly parsed, and a path-traversal "/../" part in the path could be used to override the specified host. Rated medium severity (CVSS 6.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.

RemediationAI

No vendor patch is available at time of analysis. Monitor vendor advisories for updates. Validate and canonicalize file paths. Use chroot or sandboxing. Reject input containing path separators or '../' sequences.

Affects your stack

Find out whether the stacks and servers you run are on an affected version.

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

This vulnerability is classified as Path Traversal (CWE-22), which allows attackers to access files and directories outside the intended path. Relative URLs starting with three slashes were incorrectly parsed, and a path-traversal "/../" part in the path could be used to override the specified host. This could contribute to security problems in web sites. This vulnerability affects Firefox < 120, Firefox ESR < 115.5.0, and Thunderbird < 115.5. Affected products include: Mozilla Firefox, Mozilla Firefox Esr, Mozilla Thunderbird, Debian Debian Linux.

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Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

NVD PRIMARY 6.5 MEDIUM

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

Primary rating from NVD · only source for this CVE.

CVSS VectorNVD

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

Required

Scope

Unchanged

Confidentiality

High

Integrity

None

Availability

None

DescriptionNVD

Relative URLs starting with three slashes were incorrectly parsed, and a path-traversal "/../" part in the path could be used to override the specified host. This could contribute to security problems in web sites. This vulnerability affects Firefox < 120, Firefox ESR < 115.5.0, and Thunderbird < 115.5.

Threat Intelligence Overview

EPSS Score

1.4%

Top 31% exploitable

Data Quality

2 sources

Confidence: Low

NVD

CVE.org

EPSS

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue

Severity MEDIUM

CISA KEV No

Public POC No

EPSS 1.4%

Patch available No

Active threat No

Deciding rule

MEDIUM severity (CVSS 4.0-6.9)

What every action level means

Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.

Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.

This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.

This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.

Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived

Scheduled

Exploitation· derived

None

System Exposure· derived

Open

Automatable· derived

Human Impact· derived

Medium

Priority Score

Low Medium High Critical

KEV: 0

EPSS: +1

CVSS: +32

PoC: 0

Weaponized: 0

Threat intel: 0

Gov advisory: 0

Attack Technique

Path Traversal HIGH

Path traversal exploits occur when applications use user-controlled input to construct file system paths without proper validation.

Affected Products (CPE)NVD

cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:*

cpe:2.3:a:mozilla:firefox_esr:*:*:*:*:*:*:*:*

cpe:2.3:a:mozilla:thunderbird:*:*:*:*:*:*:*:*

cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:*

cpe:2.3:o:debian:debian_linux:11.0:*:*:*:*:*:*:*

cpe:2.3:o:debian:debian_linux:12.0:*:*:*:*:*:*:*

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References

Advisories & patches

ADVISORY https://www.mozilla.org/security/advisories/mfsa2023-49/ ADVISORY https://www.mozilla.org/security/advisories/mfsa2023-50/ ADVISORY https://www.mozilla.org/security/advisories/mfsa2023-52/ REF https://bugzilla.mozilla.org/show_bug.cgi?id=1858570 REF https://lists.debian.org/debian-lts-announce/2023/11/msg00017.html REF https://lists.debian.org/debian-lts-announce/2023/11/msg00030.html REF https://www.debian.org/security/2023/dsa-5561

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