Overlayfs did not properly perform permission checking when copying up files in an overlayfs and could be exploited from within a user namespace, if, for example, unprivileged user namespaces were allowed. It was possible to have a file not readable by an unprivileged user to be copied to a mountpoint controlled by the user, like a removable device. This was introduced in kernel version 4.19 by commit d1d04ef ("ovl: stack file ops"). This was fixed in kernel version 5.8 by commits 56230d9 ("ovl: verify permissions in ovl_path_open()"), 48bd024 ("ovl: switch to mounter creds in readdir") and 05acefb ("ovl: check permission to open real file"). Additionally, commits 130fdbc ("ovl: pass correct flags for opening real directory") and 292f902 ("ovl: call secutiry hook in ovl_real_ioctl()") in kernel 5.8 might also be desired or necessary. These additional commits introduced a regression in overlay mounts within user namespaces which prevented access to files with ownership outside of the user namespace. This regression was mitigated by subsequent commit b6650da ("ovl: do not fail because of O_NOATIMEi") in kernel 5.11.
CVE-2020-16120
This medium-severity CVE scores 5.1 under NVD CVSS v3. EPSS exploit probability: 0.1%, top 80% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).
- Lower severity and no public exploit yet
A fix is available — apply it.
- CVSS v3
- 5.1
- EG Score
- 5.1(medium)
- EPSS
- 31.7%
- KEV
- Not listed
Published
February 10, 2021
Last Modified
November 21, 2024
References (22)
- security@ubuntuhttps://git.kernel.org/linus/05acefb4872dae89e772729efb194af754c877e8
- security@ubuntuhttps://git.kernel.org/linus/48bd024b8a40d73ad6b086de2615738da0c7004f
- security@ubuntuhttps://git.kernel.org/linus/56230d956739b9cb1cbde439d76227d77979a04d
- security@ubuntuhttps://git.kernel.org/linus/b6650dab404c701d7fe08a108b746542a934da84
- security@ubuntuhttps://git.kernel.org/linus/d1d04ef8572bc8c22265057bd3d5a79f223f8f52
- security@ubuntuhttps://launchpad.net/bugs/1894980
- security@ubuntuhttps://launchpad.net/bugs/1900141
- security@ubuntuhttps://ubuntu.com/USN-4576-1
- security@ubuntuhttps://ubuntu.com/USN-4577-1
- security@ubuntuhttps://ubuntu.com/USN-4578-1
- security@ubuntuhttps://www.openwall.com/lists/oss-security/2020/10/14/2
- af854a3a-2127-422b-91ae-364da2661108https://git.kernel.org/linus/05acefb4872dae89e772729efb194af754c877e8
- af854a3a-2127-422b-91ae-364da2661108https://git.kernel.org/linus/48bd024b8a40d73ad6b086de2615738da0c7004f
- af854a3a-2127-422b-91ae-364da2661108https://git.kernel.org/linus/56230d956739b9cb1cbde439d76227d77979a04d
- af854a3a-2127-422b-91ae-364da2661108https://git.kernel.org/linus/b6650dab404c701d7fe08a108b746542a934da84
Patch Availability(4)
| Vendor / Ecosystem | Fixed in / Patch | Released | Source |
|---|---|---|---|
| ubuntu | linux-image-virtual-hwe-16.04-edge (4.15.0.120.121) @ xenial | 2026-05-26 | ubuntu |
| ubuntu | linux-image-raspi2-hwe-18.04 (5.3.0.1035.24) @ bionic | 2026-05-26 | ubuntu |
| ubuntu | lowlatency-4.4 (4.4.0-168) @ xenial | 2026-05-26 | ubuntu |
| ubuntu | linux-image-virtual-hwe-20.04 (5.4.0.51.54) @ focal | 2026-05-26 | ubuntu |
Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.
Weakness Classification(2)
MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.
All Vendor Advisories
(5)
Every vendor that published an advisory referencing this CVE — pulled from our cve_vendor_advisories aggregation. Click any row for the vendor's original advisory page.
Data Freshness Timeline
(refreshed 11× in last 7d / 44× in last 30d)
Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.
- 2026-07-11 08:25 UTCEPSS rescore
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- 2026-07-01 08:48 UTCOSV refresh
- 2026-06-30 23:20 UTCEPSS rescore
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- 2026-06-23 21:31 UTCEPSS rescore
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- 2026-06-13 14:13 UTCOSV refresh
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- 2026-05-27 13:39 UTCEPSS rescore
- 2026-05-26 20:57 UTCEG score recompute
- 2026-05-26 20:57 UTCVendor advisory
- 2026-05-26 20:57 UTCGHSA enrichment
- 2026-05-26 13:42 UTCEPSS rescore
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- 2026-05-26 07:17 UTCEPSS rescore
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- 2026-05-24 16:48 UTCEPSS rescore
Frequently asked(5)
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