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CVE-2019-15793— Mishandling of file-system uid/gid with namespaces in shiftfs

Quick assessment

Affected
Ubuntu Shiftfs in the Linux kernel
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Linux kernel是美国Linux基金会发布的开源操作系统Linux所使用的内核。Canonical Ubuntu Linux是英国Canonical公司的一套Linux操作系统。 Canonical Ubuntu Linux 18.04（lts）版本和19.04版本中的Linux kernel 5.0版本和5.3版本的shiftfs实现存在安全漏洞。本地攻击者可利用该漏洞绕过DAC权限或造成其他危害。

CVSS 6.5 · Medium EPSS 0.69% · P51

Public Exploits 1

ExploitDB · 1 EDB-47693#CVE-2019-15793 [dos]
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I. Basic Information for CVE-2019-15793

Vulnerability Information
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Vulnerability Title
Mishandling of file-system uid/gid with namespaces in shiftfs
Source: CVE Program / CVE List V5
Vulnerability Description
In shiftfs, a non-upstream patch to the Linux kernel included in the Ubuntu 5.0 and 5.3 kernel series, several locations which shift ids translate user/group ids before performing operations in the lower filesystem were translating them into init_user_ns, whereas they should have been translated into the s_user_ns for the lower filesystem. This resulted in using ids other than the intended ones in the lower fs, which likely did not map into the shifts s_user_ns. A local attacker could use this to possibly bypass discretionary access control permissions.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
文件和路径信息暴露
Source: CVE Program / CVE List V5
Vulnerability Title
Canonical Ubuntu Linux kernel 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Linux kernel是美国Linux基金会发布的开源操作系统Linux所使用的内核。Canonical Ubuntu Linux是英国Canonical公司的一套Linux操作系统。 Canonical Ubuntu Linux 18.04（lts）版本和19.04版本中的Linux kernel 5.0版本和5.3版本的shiftfs实现存在安全漏洞。本地攻击者可利用该漏洞绕过DAC权限或造成其他危害。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
Ubuntu Shiftfs in the Linux kernel 5.3.0-11.12 ~ 5.3 kernel* -

II. Public POCs for CVE-2019-15793

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III. Intelligence Information for CVE-2019-15793

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Vendor Advisories for CVE-2019-15793 (2)

Other References for CVE-2019-15793 (1)

Same Patch Batch · Ubuntu · 2020-04-23 · 4 CVEs total

CVE-2019-15791 7.1 HIGH Reference count underflow in shiftfs
CVE-2019-15792 7.1 HIGH Type confusion in shiftfs
CVE-2019-15794 7.1 HIGH Reference counting error in overlayfs/shiftfs error path when used in conjuction with aufs

IV. Related Vulnerabilities

Same product: Shiftfs in the Linux kernel
Same vendor: Ubuntu
Same weakness: CWE-538

V. Comments for CVE-2019-15793

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