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

2019-11-1200:00:00

CWE-538

canonical

www.cve.org

CVSS3

6.5

Attack Vector

LOCAL

Attack Complexity

LOW

Privileges Required

LOW

User Interaction

NONE

Scope

CHANGED

Confidentiality Impact

HIGH

Integrity Impact

NONE

Availability Impact

NONE

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N

AI Score

8.4

Confidence

High

EPSS

Percentile

5.1%

JSON

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.

CNA Affected

[
  {
    "product": "Shiftfs in the Linux kernel",
    "vendor": "Ubuntu",
    "versions": [
      {
        "changes": [
          {
            "at": "5.3.0-22.24",
            "status": "unaffected"
          }
        ],
        "lessThan": "5.3 kernel*",
        "status": "affected",
        "version": "5.3.0-11.12",
        "versionType": "custom"
      },
      {
        "lessThan": "5.0.0-35.38",
        "status": "affected",
        "version": "5.0 kernel",
        "versionType": "custom"
      }
    ]
  }
]