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Fencer Intel
medium 6.5

CVE-2019-15793 json

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

published 6y ago modified 4mo ago also EUVD-2019-6716

cvss
6.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.7%
EPSS 0.7% chance of exploitation in 30 days, percentile 52%
public exploits
1
Exploit-DB

Summary

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.

Patch / fix

  • Ubuntu Shiftfs in the Linux kernel 5.0.0-35.38, 5.3.0-22.24

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Timeline

  1. First public exploit (EDB-47693)
  2. Published

Exploit prediction

0.69% chance of exploitation in the next 30 days, higher than 52% of all scored CVEs (FIRST EPSS, 2026-11-09).

Exploits and checks

  • EDB-47693 Ubuntu 19.10 - Refcount Underflow and Type Confusion in shiftfs dos, 2019-11-20

CVSS scores

assigned by version score vector
CNA 3.1 6.5 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N
NVD 3.1 8.8 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
NVD 2.0 4.6 AV:L/AC:L/Au:N/C:P/I:P/A:P

Affected products

  • Ubuntu Shiftfs in the Linux kernel

Classification

Weakness
  • CWE-538 Insertion of Sensitive Information into Externally-Accessible File or Directory
  • CWE-276 Incorrect Default Permissions
Technology feeds

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.