CVE-2020-15852 [High] | Security Vulnerability in Linux Kernel

An issue was discovered in the Linux kernel 5.5 through 5.7.9, as used in Xen through 4.13.x for x86 PV guests. An attacker may be granted the I/O port permissions of an unrelated task. This occurs because tss_invalidate_io_bitmap mishandling causes a loss of synchronization between the I/O bitmaps of TSS and Xen, aka CID-cadfad870154.

#	Date	Old EPSS score	New EPSS score	Delta (New - Old)
1	2026-06-15	0.16%	0.33%	+0.16%
2	2025-11-21	0.09%	0.16%	+0.07%
3	2025-11-18	—	0.09%	—

Date

Old EPSS score

New EPSS score

Delta (New - Old)

2026-06-15

0.16%

0.33%

+0.16%

2025-11-21

0.09%

0.16%

+0.07%

2025-11-18

—

0.09%

—

Base score	Version	Severity	Vector	Exploitability	Impact	Score source
7.8	3.1	HIGH	`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H` Click to expand Attack vector (AV:L) They already need access on the box, or another person has to do something wrong; it’s not a remote drive-by. Attack complexity (AC:L) Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup. Privileges required (PR:L) A normal user session is enough; they don’t have to be admin. User interaction (UI:N) Nobody has to click “OK” or open a trap file; it can work without a victim helping. Scope (S:U) Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems. Confidentiality (C:H) Serious risk that confidential data gets exposed in a big way. Integrity (I:H) They could widely tamper with or forge data—trust in the data is badly hurt. Availability (A:H) Could take the service down hard or make it unusable for people who depend on it.	1.8	5.9	[email protected]
4.6	2.0	MEDIUM	`AV:L/AC:L/Au:N/C:P/I:P/A:P` Click to expand Access vector (AV:L) Requires local access to the target system. Access complexity (AC:L) Exploitation conditions are straightforward and predictable. Authentication (AU:N) No authentication is required. Confidentiality impact (C:P) Partial confidentiality impact. Integrity impact (I:P) Partial integrity impact. Availability impact (A:P) Partial availability impact.	3.9	6.4	[email protected]

Base score

Version

Severity

Vector

Exploitability

Impact

Score source

7.8

3.1

HIGH

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

Attack vector (AV:L): They already need access on the box, or another person has to do something wrong; it’s not a remote drive-by.
Attack complexity (AC:L): Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:L): A normal user session is enough; they don’t have to be admin.
User interaction (UI:N): Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U): Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H): Serious risk that confidential data gets exposed in a big way.
Integrity (I:H): They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H): Could take the service down hard or make it unusable for people who depend on it.

1.8

5.9

[email protected]

4.6

2.0

MEDIUM

AV:L/AC:L/Au:N/C:P/I:P/A:P Click to expand

Access vector (AV:L): Requires local access to the target system.
Access complexity (AC:L): Exploitation conditions are straightforward and predictable.
Authentication (AU:N): No authentication is required.
Confidentiality impact (C:P): Partial confidentiality impact.
Integrity impact (I:P): Partial integrity impact.
Availability impact (A:P): Partial availability impact.

3.9

6.4

[email protected]

OS Trackers for CVE-2020-15852

vendor	priority	summary	link
`debian`	not yet assigned	CVE-2020-15852 not yet assigned priority: Debian including 1 source packages (linux), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5.	https://security-tracker.debian.org/tracker/CVE-2020-15852
`redhat`	medium	—	https://access.redhat.com/security/cve/CVE-2020-15852
`suse`	high	CVE-2020-15852 severity important: SUSE including 17 source package names (kernel-default, kernel-default-base, …), 286 product×package rows across 45 product lines (HPE Helion OpenStack 8, SUSE CaaS Platform 3.0, … (45 product lines)): Known Not Affected 286.	https://www.suse.com/security/cve/CVE-2020-15852/
`ubuntu`	medium	CVE-2020-15852 medium priority: Ubuntu including 41 source packages (linux, linux-aws, …), 246 status rows across 6 suites (bionic, focal, groovy, trusty, upstream, xenial): DNE 136, not-affected 52, released 42, ignored 16.	https://ubuntu.com/security/CVE-2020-15852

Affected software / configurations for CVE-2020-15852

Vendor	Product	Version	Raw CPE
linux	linux_kernel	>= 5.5, <= 5.7.9	cpe:2.3:o:linux:linux_kernel::::::::
xen	xen	<= 4.13.1	cpe:2.3:o:xen:xen:::::::x86:*
netapp	cloud_backup	—	cpe:2.3:a:netapp:cloud_backup:-:::::::*
netapp	steelstore_cloud_integrated_storage	—	cpe:2.3:a:netapp:steelstore_cloud_integrated_storage:-:::::::*
netapp	solidfire_baseboard_management_controller	—	cpe:2.3:h:netapp:solidfire_baseboard_management_controller:-:::::::*

References for CVE-2020-15852

URL	Tags
http://www.openwall.com/lists/oss-security/2020/07/21/2	Mailing List Third Party Advisory
http://xenbits.xen.org/xsa/advisory-329.html	Patch Third Party Advisory
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=cadfad870154e14f745ec845708bc17d166065f2	Mailing List Patch Vendor Advisory
https://github.com/torvalds/linux/commit/cadfad870154e14f745ec845708bc17d166065f2	Patch Third Party Advisory
https://security.netapp.com/advisory/ntap-20200810-0001/	Third Party Advisory

URL

CVE-2020-15852

Exploit prediction scoring system (EPSS) score for CVE-2020-15852

Common vulnerability scoring system (CVSS) metrics for CVE-2020-15852

Weakness enumeration for CVE-2020-15852

OS Trackers for CVE-2020-15852

Affected software / configurations for CVE-2020-15852

References for CVE-2020-15852