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Bash CVE-2019-18276

HIGH
Improper Check for Dropped Privileges (CWE-273)
2019-11-28 cve@mitre.org
7.8
CVSS 3.1 · NVD
View

Vulnerability Assessment

Weakness
CWE
ASVS 5.0
V8 - Authorization Privilege drop verification
Impact

CVSS score of 7.8 (HIGH). Attack characteristics: local attack vector, low complexity, low privileges required, no user interaction not required. Public proof-of-concept exploit code is available.

Exploit ScenarioDerived

Successful exploitation could compromise the high-severity affected system.

This Week Schedule remediation this week. Why: HIGH severity (CVSS 7.0-8.9).
Patch available 2.6% exploitation probability (EPSS)

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AnalysisAI

An issue was discovered in disable_priv_mode in shell.c in GNU Bash through 5.0 patch 11. Rated high severity (CVSS 7.8), this vulnerability is low attack complexity. Public exploit code available.

RemediationAI

A vendor patch is available. Apply the latest security update as soon as possible. Apply vendor patches when available. Implement network segmentation and monitoring as interim mitigations.

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Technical ContextAI · show details

This vulnerability is classified under CWE-273. An issue was discovered in disable_priv_mode in shell.c in GNU Bash through 5.0 patch 11. By default, if Bash is run with its effective UID not equal to its real UID, it will drop privileges by setting its effective UID to its real UID. However, it does so incorrectly. On Linux and other systems that support "saved UID" functionality, the saved UID is not dropped. An attacker with command execution in the shell can use "enable -f" for runtime loading of a new builtin, which can be a shared object that calls setuid() and therefore regains privileges. However, binaries running with an effective UID of 0 are unaffected. Affected products include: Gnu Bash, Netapp Hci Management Node, Netapp Oncommand Unified Manager, Netapp Solidfire, Oracle Communications Cloud Native Core Policy. Version information: through 5.0.

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Severity by source

NVD PRIMARY 7.8 HIGH
AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Primary rating from NVD · only source for this CVE.

CVSS VectorNVD

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

DescriptionNVD

An issue was discovered in disable_priv_mode in shell.c in GNU Bash through 5.0 patch 11. By default, if Bash is run with its effective UID not equal to its real UID, it will drop privileges by setting its effective UID to its real UID. However, it does so incorrectly. On Linux and other systems that support "saved UID" functionality, the saved UID is not dropped. An attacker with command execution in the shell can use "enable -f" for runtime loading of a new builtin, which can be a shared object that calls setuid() and therefore regains privileges. However, binaries running with an effective UID of 0 are unaffected.

Threat Intelligence Overview

EPSS Score
2.6%
Top 16% exploitable
Exploit
POC
Public exploit code exists
Data Quality
4 sources
Confidence: Medium

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 2.6%
Patch available Yes
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
Small
Automatable· derived
No
Human Impact· derived
Medium

Priority Score

62
Low Medium High Critical
KEV: 0
EPSS: +3
CVSS: +39
PoC: +20
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

Information disclosure occurs when an application unintentionally exposes sensitive data that aids attackers in reconnaissance or directly compromises security.

Affected Products (CPE)NVD

cpe:2.3:a:gnu:bash:*:*:*:*:*:*:*:*
cpe:2.3:a:gnu:bash:5.0:beta1:*:*:*:*:*:*
cpe:2.3:a:gnu:bash:5.0:beta2:*:*:*:*:*:*
cpe:2.3:a:gnu:bash:5.0:patch1:*:*:*:*:*:*
cpe:2.3:a:gnu:bash:5.0:patch10:*:*:*:*:*:*
cpe:2.3:a:gnu:bash:5.0:patch11:*:*:*:*:*:*
cpe:2.3:a:gnu:bash:5.0:patch2:*:*:*:*:*:*
cpe:2.3:a:gnu:bash:5.0:patch3:*:*:*:*:*:*
cpe:2.3:a:gnu:bash:5.0:patch4:*:*:*:*:*:*
cpe:2.3:a:gnu:bash:5.0:patch5:*:*:*:*:*:*
cpe:2.3:a:gnu:bash:5.0:patch6:*:*:*:*:*:*
cpe:2.3:a:gnu:bash:5.0:patch7:*:*:*:*:*:*
cpe:2.3:a:gnu:bash:5.0:patch8:*:*:*:*:*:*
cpe:2.3:a:gnu:bash:5.0:patch9:*:*:*:*:*:*
cpe:2.3:a:gnu:bash:5.0:rc1:*:*:*:*:*:*
cpe:2.3:a:netapp:hci_management_node:-:*:*:*:*:*:*:*
cpe:2.3:a:netapp:oncommand_unified_manager:*:*:*:*:*:vmware_vsphere:*:*
cpe:2.3:a:netapp:solidfire:-:*:*:*:*:*:*:*
cpe:2.3:a:oracle:communications_cloud_native_core_policy:1.14.0:*:*:*:*:*:*:*

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