What is the CVSS score of CVE-2024-34535?

CVE-2024-34535 has a CVSS 3.1 base score of 5.9 (Medium). CVSS vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:L/A:N. EPSS exploitation probability: 0.4%.

Mastodon CVE-2024-34535

MEDIUM

HTTP Request/Response Smuggling (CWE-444)

2024-10-03 cve@mitre.org

Authentication Bypass Request Smuggling Mastodon Joinmastodon

5.9

CVSS 3.1 · Vendor: mitre

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Vulnerability Assessment

Weakness	CWE CWE-444 OWASP Top 10:2025 A06:2025 - Insecure Design ASVS 5.0 V4 - API and Web Service HTTP request consistency
Impact	CVSS score of 5.9 (MEDIUM). Attack characteristics: network attack vector, high complexity, low privileges required, no user interaction not required.
Exploit ScenarioDerived	A remote attacker could manipulate HTTP request interpretation between frontend and backend servers by sending crafted requests to the affected application.

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

No patch listed yet 0.4% exploitation probability (EPSS)

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AnalysisAI

In Mastodon 4.1.6, API endpoint rate limiting can be bypassed by setting a crafted HTTP request header. Rated medium severity (CVSS 5.9), this vulnerability is remotely exploitable. No vendor patch available.

RemediationAI

No vendor patch is available at time of analysis. Monitor vendor advisories for updates. Enforce strict HTTP parsing, normalize requests at proxy layer, use HTTP/2 end-to-end, reject ambiguous headers.

Affects your stack

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Technical ContextAI · show details

This vulnerability is classified as HTTP Request/Response Smuggling (CWE-444), which allows attackers to manipulate HTTP request interpretation between frontend and backend servers. In Mastodon 4.1.6, API endpoint rate limiting can be bypassed by setting a crafted HTTP request header. Affected products include: Joinmastodon Mastodon.

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Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

Vendor (mitre) PRIMARY 5.9 MEDIUM

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

Primary rating from Vendor (mitre) · only source for this CVE.

CVSS VectorVendor: mitre

Attack Vector

Network

Attack Complexity

High

Privileges Required

Low

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

Low

Availability

None

DescriptionCVE.org

In Mastodon 4.1.6, API endpoint rate limiting can be bypassed by setting a crafted HTTP request header.

Threat Intelligence Overview

EPSS Score

0.4%

Top 70% exploitable

Data Quality

3 sources

Confidence: Low

NVD

CVE.org

EPSS

GitHub

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 0.4%

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: 0

CVSS: +30

PoC: 0

Weaponized: 0

Threat intel: 0

Gov advisory: 0

Attack Technique

Authentication Bypass CRITICAL

Authentication bypass attacks exploit flaws in the verification mechanisms that control access to systems and applications.

HTTP Request Smuggling HIGH

HTTP request smuggling exploits inconsistencies in how front-end and back-end servers parse HTTP message boundaries.

Affected Products (CPE)CVE.org

cpe:2.3:a:joinmastodon:mastodon:*:*:*:*:*:*:*:*

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References

Advisories & patches

REF https://github.com/mastodon/mastodon/security/advisories/GHSA-q3rg-xx5v-4mxh REF https://github.com/mastodon/mastodon/tags

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GitHub PoC

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