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CVE-2019-15794· NVD / CVE Program· CNA canonical

Reference counting error in overlayfs/shiftfs error path when used in conjuction with aufs

Overlayfs in the Linux kernel and shiftfs, a non-upstream patch to the Linux kernel included in the Ubuntu 5.0 and 5.3 kernel series, both replace vma->vm_file in their mmap handlers. On error the original value is not restored, and the reference is put for the file to which vm_file points. On upstream kernels this is not an issue, as no callers dereference vm_file following after call_mmap() returns an error. However, the aufs patchs change mmap_region() to replace the fput() using a local variable with vma_fput(), which will fput() vm_file, leading to a refcount underflow.

MediumCVSS 6.7 · v3.1—Proof of concept Fix available
Published
Apr 23, 2020
Updated
Jun 16, 2026
EPSS
1.2% · 66th percentile
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Report tools

JSON

Action score

26

Monitor

Low priority for now.

CVSS
26 / 40 · 6.7 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 1.2%

CNA vs NVD score

NVD
6.7
CNA · canonical
7.1
0.4 point gap

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

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Affected systems

VendorProduct
linuxlinux kernel
canonicalubuntu linux

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • canonical ubuntu linux18.04
  • canonical ubuntu linux19.10
  • linux linux kernel5.0
  • linux linux kernel5.3

Versions reported by the vendor

Affected version ranges reported by the assigning authority (canonical). Independent of NVD's CPE analysis and usually ahead of it.

  • Ubuntu Linux kernel

    • 5.3 kernel and later · before 5.3.0-24.26affected
    • 5.0 kernel and later · before 5.0.0-37.40affected

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Debian:12linuxbefore 5.16.7-15.16.7-1
Red Hat:enterprise_linux:8::baseosbpftoolbefore 0:4.18.0-348.el80:4.18.0-348.el8
Red Hat:enterprise_linux:8::baseosbpftool-debuginfobefore 0:4.18.0-348.el80:4.18.0-348.el8
Red Hat:enterprise_linux:8::baseoskernelbefore 0:4.18.0-348.el80:4.18.0-348.el8
Red Hat:enterprise_linux:8::baseoskernel-abi-stablelistsbefore 0:4.18.0-348.el80:4.18.0-348.el8
Red Hat:enterprise_linux:8::baseoskernel-corebefore 0:4.18.0-348.el80:4.18.0-348.el8
Red Hat:enterprise_linux:8::baseoskernel-debugbefore 0:4.18.0-348.el80:4.18.0-348.el8
Red Hat:enterprise_linux:8::baseoskernel-debug-corebefore 0:4.18.0-348.el80:4.18.0-348.el8
Red Hat:enterprise_linux:8::baseoskernel-debug-debuginfobefore 0:4.18.0-348.el80:4.18.0-348.el8
Red Hat:enterprise_linux:8::baseoskernel-debug-develbefore 0:4.18.0-348.el80:4.18.0-348.el8
Red Hat:enterprise_linux:8::baseoskernel-debug-modulesbefore 0:4.18.0-348.el80:4.18.0-348.el8
Red Hat:enterprise_linux:8::baseoskernel-debug-modules-extrabefore 0:4.18.0-348.el80:4.18.0-348.el8
Red Hat:enterprise_linux:8::baseoskernel-debuginfobefore 0:4.18.0-348.el80:4.18.0-348.el8
Red Hat:enterprise_linux:8::baseoskernel-debuginfo-common-aarch64before 0:4.18.0-348.el80:4.18.0-348.el8
Red Hat:enterprise_linux:8::baseoskernel-debuginfo-common-ppc64lebefore 0:4.18.0-348.el80:4.18.0-348.el8
Red Hat:enterprise_linux:8::baseoskernel-debuginfo-common-s390xbefore 0:4.18.0-348.el80:4.18.0-348.el8
Red Hat:enterprise_linux:8::baseoskernel-debuginfo-common-x86_64before 0:4.18.0-348.el80:4.18.0-348.el8
Red Hat:enterprise_linux:8::baseoskernel-develbefore 0:4.18.0-348.el80:4.18.0-348.el8
Red Hat:enterprise_linux:8::baseoskernel-docbefore 0:4.18.0-348.el80:4.18.0-348.el8
Red Hat:enterprise_linux:8::baseoskernel-modulesbefore 0:4.18.0-348.el80:4.18.0-348.el8
Red Hat:enterprise_linux:8::baseoskernel-modules-extrabefore 0:4.18.0-348.el80:4.18.0-348.el8
Red Hat:enterprise_linux:8::baseoskernel-toolsbefore 0:4.18.0-348.el80:4.18.0-348.el8
Red Hat:enterprise_linux:8::baseoskernel-tools-debuginfobefore 0:4.18.0-348.el80:4.18.0-348.el8
Red Hat:enterprise_linux:8::baseoskernel-tools-libsbefore 0:4.18.0-348.el80:4.18.0-348.el8

+11

Same product

linux: all records

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Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
debian:linux5.16.7-1 · Debian:12Package registry (OSV)
red hat:bpftool0:4.18.0-348.el8 · Red Hat:enterprise_linux:8::baseosPackage registry (OSV)
red hat:bpftool-debuginfo0:4.18.0-348.el8 · Red Hat:enterprise_linux:8::baseosPackage registry (OSV)
red hat:kernel0:4.18.0-348.el8 · Red Hat:enterprise_linux:8::baseosPackage registry (OSV)
red hat:kernel-abi-stablelists0:4.18.0-348.el8 · Red Hat:enterprise_linux:8::baseosPackage registry (OSV)
red hat:kernel-core0:4.18.0-348.el8 · Red Hat:enterprise_linux:8::baseosPackage registry (OSV)
red hat:kernel-debug0:4.18.0-348.el8 · Red Hat:enterprise_linux:8::baseosPackage registry (OSV)
red hat:kernel-debug-core0:4.18.0-348.el8 · Red Hat:enterprise_linux:8::baseosPackage registry (OSV)
red hat:kernel-debug-debuginfo0:4.18.0-348.el8 · Red Hat:enterprise_linux:8::baseosPackage registry (OSV)
red hat:kernel-debug-devel0:4.18.0-348.el8 · Red Hat:enterprise_linux:8::baseosPackage registry (OSV)
red hat:kernel-debug-modules0:4.18.0-348.el8 · Red Hat:enterprise_linux:8::baseosPackage registry (OSV)
red hat:kernel-debug-modules-extra0:4.18.0-348.el8 · Red Hat:enterprise_linux:8::baseosPackage registry (OSV)
red hat:kernel-debuginfo0:4.18.0-348.el8 · Red Hat:enterprise_linux:8::baseosPackage registry (OSV)

Exploit status

Proof of concept available

A public proof of concept or detection signature exists. Exploit knowledge is out there; don't delay patching.

Evidence

  • Exploit-DB entry ×1

Noroxi does not host or link to exploit code. Metasploit module names and Nuclei template ids are shown (names, not code); Exploit-DB entries and PoC repositories are given as counts only.

Public exploit evidence
SourceKindDate
Exploit-DB entrydos2019-11-20

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

  1. First PoC-156 d
  2. Published
  3. TodaySep 30, 2026+2351 d
EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

  • Someone with local access to the system can trigger it.
  • Administrator privileges are required.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
high · data can be read
Integrity
high · data or configuration can be modified
Availability
high · the service can be disrupted
Attack vector
Local
Attack complexity
Low
Privileges required
High
User interaction
None
Scope
Unchanged
Confidentiality impact
High
Integrity impact
High
Availability impact
High

Weakness class (CWE)

CWE-672 · Operation on a Resource after Expiration or Release

CVSS vector

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

nvd-primary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Noroxi analysis

No Noroxi analysis for this record yet

We don't hand-write analysis for all 385,000+ vulnerabilities; that wouldn't be honest. For notable, high-impact vulnerabilities our team writes the mechanism, detection and remediation steps.

We use this product, ask for help

Change log

  1. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records