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Modsecurity CVE-2020-15598

HIGH
Loop with Unreachable Exit Condition (Infinite Loop) (CWE-835)
2020-10-06 cve@mitre.org
7.5
CVSS 3.1 · NVD
View

Vulnerability Assessment

Weakness
CWE
ASVS 5.0
V15 - Secure Coding and Architecture Loop termination conditions
MITRE ATT&CK

1 technique across 1 tactic: Impact

The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up.

Impact

CVSS score of 7.5 (HIGH). Attack characteristics: network attack vector, low complexity, no privileges required, no user interaction not required. Public proof-of-concept exploit code is available.

Exploit ScenarioDerived

This vulnerability can be exploited remotely over the network. Successful exploitation could compromise the high-severity affected system.

This Week Schedule remediation this week. Why: HIGH severity (CVSS 7.0-8.9).
No patch listed yet 3.2% exploitation probability (EPSS)

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AnalysisAI

Trustwave ModSecurity 3.x through 3.0.4 allows denial of service via a special request. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Public exploit code available and no vendor patch available.

RemediationAI

No vendor patch is available at time of analysis. Monitor vendor advisories for updates. Apply vendor patches when available. Implement network segmentation and monitoring as interim mitigations.

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 under CWE-835. Trustwave ModSecurity 3.x through 3.0.4 allows denial of service via a special request. NOTE: The discoverer reports "Trustwave has signaled they are disputing our claims." The CVE suggests that there is a security issue with how ModSecurity handles regular expressions that can result in a Denial of Service condition. The vendor does not consider this as a security issue because1) there is no default configuration issue here. An attacker would need to know that a rule using a potentially problematic regular expression was in place, 2) the attacker would need to know the basic nature of the regular expression itself to exploit any resource issues. It's well known that regular expression usage can be taxing on system resources regardless of the use case. It is up to the administrator to decide on when it is appropriate to trade resources for potential security benefit Affected products include: Owasp Modsecurity, Debian Debian Linux. Version information: through 3.0.4.

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  • Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

NVD PRIMARY 7.5 HIGH
AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Primary rating from NVD · only source for this CVE.

CVSS VectorNVD

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

DescriptionNVD

Trustwave ModSecurity 3.x through 3.0.4 allows denial of service via a special request. NOTE: The discoverer reports "Trustwave has signaled they are disputing our claims." The CVE suggests that there is a security issue with how ModSecurity handles regular expressions that can result in a Denial of Service condition. The vendor does not consider this as a security issue because1) there is no default configuration issue here. An attacker would need to know that a rule using a potentially problematic regular expression was in place, 2) the attacker would need to know the basic nature of the regular expression itself to exploit any resource issues. It's well known that regular expression usage can be taxing on system resources regardless of the use case. It is up to the administrator to decide on when it is appropriate to trade resources for potential security benefit

Threat Intelligence Overview

EPSS Score
3.2%
Top 13% exploitable
Exploit
POC
Public exploit code exists
Data Quality
2 sources
Confidence: Low

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 HIGH
CISA KEV No
Public POC Yes
EPSS 3.2%
Patch available No
Active threat No
Deciding rule
HIGH severity (CVSS 7.0-8.9)
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
Poc
System Exposure· derived
Open
Automatable· derived
Yes
Human Impact· derived
Medium

Priority Score

61
Low Medium High Critical
KEV: 0
EPSS: +3
CVSS: +38
PoC: +20
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

Denial of Service attacks render applications or systems unavailable by overwhelming resources or triggering failure conditions.

Affected Products (CPE)NVD

cpe:2.3:a:owasp:modsecurity:*:*:*:*:*:*:*:*
cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:*
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