CVE-2023-52973 [High] | Use-After-Free in Linux Kernel

In the Linux kernel, the following vulnerability has been resolved: vc_screen: move load of struct vc_data pointer in vcs_read() to avoid UAF After a call to console_unlock() in vcs_read() the vc_data struct can be freed by vc_deallocate(). Because of that, the struct vc_data pointer load must be done at the top of while loop in vcs_read() to avoid a UAF when vcs_size() is called. Syzkaller reported a UAF in vcs_size(). BUG: KASAN: use-after-free in vcs_size (drivers/tty/vt/vc_screen.c:215) Read of size 4 at addr ffff8881137479a8 by task 4a005ed81e27e65/1537 CPU: 0 PID: 1537 Comm: 4a005ed81e27e65 Not tainted 6.2.0-rc5 #1 Hardware name: Red Hat KVM, BIOS 1.15.0-2.module Call Trace: <TASK> __asan_report_load4_noabort (mm/kasan/report_generic.c:350) vcs_size (drivers/tty/vt/vc_screen.c:215) vcs_read (drivers/tty/vt/vc_screen.c:415) vfs_read (fs/read_write.c:468 fs/read_write.c:450) ... </TASK> Allocated by task 1191: ... kmalloc_trace (mm/slab_common.c:1069) vc_allocate (./include/linux/slab.h:580 ./include/linux/slab.h:720 drivers/tty/vt/vt.c:1128 drivers/tty/vt/vt.c:1108) con_install (drivers/tty/vt/vt.c:3383) tty_init_dev (drivers/tty/tty_io.c:1301 drivers/tty/tty_io.c:1413 drivers/tty/tty_io.c:1390) tty_open (drivers/tty/tty_io.c:2080 drivers/tty/tty_io.c:2126) chrdev_open (fs/char_dev.c:415) do_dentry_open (fs/open.c:883) vfs_open (fs/open.c:1014) ... Freed by task 1548: ... kfree (mm/slab_common.c:1021) vc_port_destruct (drivers/tty/vt/vt.c:1094) tty_port_destructor (drivers/tty/tty_port.c:296) tty_port_put (drivers/tty/tty_port.c:312) vt_disallocate_all (drivers/tty/vt/vt_ioctl.c:662 (discriminator 2)) vt_ioctl (drivers/tty/vt/vt_ioctl.c:903) tty_ioctl (drivers/tty/tty_io.c:2776) ... The buggy address belongs to the object at ffff888113747800 which belongs to the cache kmalloc-1k of size 1024 The buggy address is located 424 bytes inside of 1024-byte region [ffff888113747800, ffff888113747c00) The buggy address belongs to the physical page: page:00000000b3fe6c7c refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x113740 head:00000000b3fe6c7c order:3 compound_mapcount:0 subpages_mapcount:0 compound_pincount:0 anon flags: 0x17ffffc0010200(slab|head|node=0|zone=2|lastcpupid=0x1fffff) raw: 0017ffffc0010200 ffff888100042dc0 0000000000000000 dead000000000001 raw: 0000000000000000 0000000000100010 00000001ffffffff 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff888113747880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888113747900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > ffff888113747980: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff888113747a00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888113747a80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ================================================================== Disabling lock debugging due to kernel taint

#	Date	Old EPSS score	New EPSS score	Delta (New - Old)
1	2026-06-17	0.25%	0.26%	+0.01%
2	2026-06-15	0.01%	0.25%	+0.24%
3	2025-03-28	—	0.01%	—

Date

Old EPSS score

New EPSS score

Delta (New - Old)

2026-06-17

0.25%

0.26%

+0.01%

2026-06-15

0.01%

0.25%

+0.24%

2025-03-28

—

0.01%

—

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	134c704f-9b21-4f2e-91b3-4a467353bcc0

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

134c704f-9b21-4f2e-91b3-4a467353bcc0

OS Trackers for CVE-2023-52973

vendor	priority	summary	link
`debian`	not yet assigned	CVE-2023-52973 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-2023-52973
`redhat`	medium	—	https://access.redhat.com/security/cve/CVE-2023-52973
`suse`	medium	—	https://www.suse.com/security/cve/CVE-2023-52973/
`ubuntu`	medium	CVE-2023-52973 medium priority: Ubuntu including 158 source packages (linux, linux-allwinner-5.19, …), 1551 status rows across 10 suites (bionic, focal, jammy, noble, oracular, plucky, questing, trusty, upstream, xenial): DNE 1145, released 161, ignored 146, not-affected 98, needs-triage 1.	https://ubuntu.com/security/CVE-2023-52973

Affected software / configurations for CVE-2023-52973

Vendor	Product	Version	Raw CPE
linux	linux_kernel	>= 2.6.38, < 4.14.329	cpe:2.3:o:linux:linux_kernel::::::::
linux	linux_kernel	>= 4.15, < 4.19.273	cpe:2.3:o:linux:linux_kernel::::::::
linux	linux_kernel	>= 4.20, < 5.4.232	cpe:2.3:o:linux:linux_kernel::::::::
linux	linux_kernel	>= 5.5, < 5.10.168	cpe:2.3:o:linux:linux_kernel::::::::
linux	linux_kernel	>= 5.11, < 5.15.93	cpe:2.3:o:linux:linux_kernel::::::::
linux	linux_kernel	>= 5.16, < 6.1.11	cpe:2.3:o:linux:linux_kernel::::::::
linux	linux_kernel	6.2	cpe:2.3:o:linux:linux_kernel:6.2:rc1::::::
linux	linux_kernel	6.2	cpe:2.3:o:linux:linux_kernel:6.2:rc2::::::
linux	linux_kernel	6.2	cpe:2.3:o:linux:linux_kernel:6.2:rc3::::::
linux	linux_kernel	6.2	cpe:2.3:o:linux:linux_kernel:6.2:rc4::::::
linux	linux_kernel	6.2	cpe:2.3:o:linux:linux_kernel:6.2:rc5::::::
linux	linux_kernel	6.2	cpe:2.3:o:linux:linux_kernel:6.2:rc6::::::

References for CVE-2023-52973

URL	Tags
https://git.kernel.org/stable/c/226fae124b2dac217ea5436060d623ff3385bc34	Patch
https://git.kernel.org/stable/c/55515d7d8743b71b80bfe68e89eb9d92630626ab	Patch
https://git.kernel.org/stable/c/6332f52f44b9776568bf3c0b714ddfb0bb175e78	Patch
https://git.kernel.org/stable/c/8506f16aae9daf354e3732bcfd447e2a97f023df	Patch
https://git.kernel.org/stable/c/af79ea9a2443016f64d8fd8d72020cc874f0e066	Patch
https://git.kernel.org/stable/c/d0332cbf53dad06a22189cc341391237f4ea6d9f	Patch
https://git.kernel.org/stable/c/fc9e27f3ba083534b8bbf72ab0f5c810ffdc7d18	Patch

URL

CVE-2023-52973 | vc_screen: move load of struct vc_data pointer in vcs_read() to avoid UAF

Exploit prediction scoring system (EPSS) score for CVE-2023-52973

Common vulnerability scoring system (CVSS) metrics for CVE-2023-52973

Weakness enumeration for CVE-2023-52973

OS Trackers for CVE-2023-52973

Affected software / configurations for CVE-2023-52973

References for CVE-2023-52973