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Grsecurity CVE-2019-5023

MEDIUM
Memory Leak (CWE-401)
2019-10-31 talos-cna@cisco.com
5.9
CVSS 3.1 · NVD
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Vulnerability Assessment

Weakness
CWE
ASVS 5.0
V15 - Secure Coding and Architecture Resource cleanup, leak prevention
Impact

CVSS score of 5.9 (MEDIUM). Attack characteristics: network attack vector, high complexity, no privileges required, no user interaction not required. Public proof-of-concept exploit code is available.

Exploit ScenarioDerived

A remote attacker could exhaust available memory leading to denial of service 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 0.7% exploitation probability (EPSS)

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AnalysisAI

An exploitable vulnerability exists in the grsecurity PaX patch for the function read_kmem, in PaX from version pax-linux-4.9.8-test1 to 4.9.24-test7, grsecurity official from version. Rated medium severity (CVSS 5.9), this vulnerability is remotely exploitable, no authentication required. Public exploit code available and no vendor patch available.

RemediationAI

No vendor patch is available at time of analysis. Monitor vendor advisories for updates. Ensure all allocated memory is properly freed. Use RAII patterns or garbage-collected languages.

Affects your stack

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Technical ContextAI · show details

This vulnerability is classified as Memory Leak (CWE-401), which allows attackers to exhaust available memory leading to denial of service. An exploitable vulnerability exists in the grsecurity PaX patch for the function read_kmem, in PaX from version pax-linux-4.9.8-test1 to 4.9.24-test7, grsecurity official from version grsecurity-3.1-4.9.8-201702060653 to grsecurity-3.1-4.9.24-201704252333, grsecurity unofficial from version v4.9.25-unofficialgrsec to v4.9.74-unofficialgrsec. PaX adds a temp buffer to the read_kmem function, which is never freed when an invalid address is supplied. This results in a memory leakage that can lead to a crash of the system. An attacker needs to induce a read to /dev/kmem using an invalid address to exploit this vulnerability. Affected products include: Opensrcsec Grsecurity, Opensrcsec Pax.

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  • Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

NVD PRIMARY 5.9 MEDIUM
AV:N/AC:H/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
High
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

DescriptionNVD

An exploitable vulnerability exists in the grsecurity PaX patch for the function read_kmem, in PaX from version pax-linux-4.9.8-test1 to 4.9.24-test7, grsecurity official from version grsecurity-3.1-4.9.8-201702060653 to grsecurity-3.1-4.9.24-201704252333, grsecurity unofficial from version v4.9.25-unofficialgrsec to v4.9.74-unofficialgrsec. PaX adds a temp buffer to the read_kmem function, which is never freed when an invalid address is supplied. This results in a memory leakage that can lead to a crash of the system. An attacker needs to induce a read to /dev/kmem using an invalid address to exploit this vulnerability.

Threat Intelligence Overview

EPSS Score
0.7%
Top 50% 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 MEDIUM
CISA KEV No
Public POC Yes
EPSS 0.7%
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
Poc
System Exposure· derived
Open
Automatable· derived
No
Human Impact· derived
Medium

Priority Score

51
Low Medium High Critical
KEV: 0
EPSS: +1
CVSS: +30
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:opensrcsec:grsecurity:*:*:*:*:official:*:*:*
cpe:2.3:a:opensrcsec:grsecurity:*:*:*:*:unofficial:*:*:*
cpe:2.3:a:opensrcsec:pax:*:*:*:*:*:*:*:*

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