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CVE-2023-52973 (GCVE-0-2023-52973)

Vulnerability from cvelistv5 – Published: 2025-03-27 16:43 – Updated: 2026-08-05 09:12
VLAI
Title
vc_screen: move load of struct vc_data pointer in vcs_read() to avoid UAF
Summary
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
Severity
7.8 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
SSVC
Exploitation: none Automatable: no Technical Impact: total
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2025-03-27 16:59 UTC
CWE
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: ac751efa6a0d70f2c9daef5c7e3a92270f5c2dff , < af79ea9a2443016f64d8fd8d72020cc874f0e066 (git)
Affected: ac751efa6a0d70f2c9daef5c7e3a92270f5c2dff , < 6332f52f44b9776568bf3c0b714ddfb0bb175e78 (git)
Affected: ac751efa6a0d70f2c9daef5c7e3a92270f5c2dff , < d0332cbf53dad06a22189cc341391237f4ea6d9f (git)
Affected: ac751efa6a0d70f2c9daef5c7e3a92270f5c2dff , < 55515d7d8743b71b80bfe68e89eb9d92630626ab (git)
Affected: ac751efa6a0d70f2c9daef5c7e3a92270f5c2dff , < fc9e27f3ba083534b8bbf72ab0f5c810ffdc7d18 (git)
Affected: ac751efa6a0d70f2c9daef5c7e3a92270f5c2dff , < 8506f16aae9daf354e3732bcfd447e2a97f023df (git)
Affected: ac751efa6a0d70f2c9daef5c7e3a92270f5c2dff , < 226fae124b2dac217ea5436060d623ff3385bc34 (git)
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Linux Linux Affected: 2.6.38
Unaffected: 0 , < 2.6.38 (semver)
Unaffected: 4.14.329 , ≤ 4.14.* (semver)
Unaffected: 4.19.273 , ≤ 4.19.* (semver)
Unaffected: 5.4.232 , ≤ 5.4.* (semver)
Unaffected: 5.10.168 , ≤ 5.10.* (semver)
Unaffected: 5.15.93 , ≤ 5.15.* (semver)
Unaffected: 6.1.11 , ≤ 6.1.* (semver)
Unaffected: 6.2 , ≤ * (original_commit_for_fix)
guessed Create a notification for this product.
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          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nvc_screen: move load of struct vc_data pointer in vcs_read() to avoid UAF\n\nAfter a call to console_unlock() in vcs_read() the vc_data struct can be\nfreed by vc_deallocate(). Because of that, the struct vc_data pointer\nload must be done at the top of while loop in vcs_read() to avoid a UAF\nwhen vcs_size() is called.\n\nSyzkaller reported a UAF in vcs_size().\n\nBUG: KASAN: use-after-free in vcs_size (drivers/tty/vt/vc_screen.c:215)\nRead of size 4 at addr ffff8881137479a8 by task 4a005ed81e27e65/1537\n\nCPU: 0 PID: 1537 Comm: 4a005ed81e27e65 Not tainted 6.2.0-rc5 #1\nHardware name: Red Hat KVM, BIOS 1.15.0-2.module\nCall Trace:\n  \u003cTASK\u003e\n__asan_report_load4_noabort (mm/kasan/report_generic.c:350)\nvcs_size (drivers/tty/vt/vc_screen.c:215)\nvcs_read (drivers/tty/vt/vc_screen.c:415)\nvfs_read (fs/read_write.c:468 fs/read_write.c:450)\n...\n  \u003c/TASK\u003e\n\nAllocated by task 1191:\n...\nkmalloc_trace (mm/slab_common.c:1069)\nvc_allocate (./include/linux/slab.h:580 ./include/linux/slab.h:720\n     drivers/tty/vt/vt.c:1128 drivers/tty/vt/vt.c:1108)\ncon_install (drivers/tty/vt/vt.c:3383)\ntty_init_dev (drivers/tty/tty_io.c:1301 drivers/tty/tty_io.c:1413\n     drivers/tty/tty_io.c:1390)\ntty_open (drivers/tty/tty_io.c:2080 drivers/tty/tty_io.c:2126)\nchrdev_open (fs/char_dev.c:415)\ndo_dentry_open (fs/open.c:883)\nvfs_open (fs/open.c:1014)\n...\n\nFreed by task 1548:\n...\nkfree (mm/slab_common.c:1021)\nvc_port_destruct (drivers/tty/vt/vt.c:1094)\ntty_port_destructor (drivers/tty/tty_port.c:296)\ntty_port_put (drivers/tty/tty_port.c:312)\nvt_disallocate_all (drivers/tty/vt/vt_ioctl.c:662 (discriminator 2))\nvt_ioctl (drivers/tty/vt/vt_ioctl.c:903)\ntty_ioctl (drivers/tty/tty_io.c:2776)\n...\n\nThe buggy address belongs to the object at ffff888113747800\n  which belongs to the cache kmalloc-1k of size 1024\nThe buggy address is located 424 bytes inside of\n  1024-byte region [ffff888113747800, ffff888113747c00)\n\nThe buggy address belongs to the physical page:\npage:00000000b3fe6c7c refcount:1 mapcount:0 mapping:0000000000000000\n     index:0x0 pfn:0x113740\nhead:00000000b3fe6c7c order:3 compound_mapcount:0 subpages_mapcount:0\n     compound_pincount:0\nanon flags: 0x17ffffc0010200(slab|head|node=0|zone=2|lastcpupid=0x1fffff)\nraw: 0017ffffc0010200 ffff888100042dc0 0000000000000000 dead000000000001\nraw: 0000000000000000 0000000000100010 00000001ffffffff 0000000000000000\npage dumped because: kasan: bad access detected\n\nMemory state around the buggy address:\n  ffff888113747880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb\n  ffff888113747900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb\n\u003e ffff888113747980: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb\n                                   ^\n  ffff888113747a00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb\n  ffff888113747a80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb\n==================================================================\nDisabling lock debugging due to kernel taint"
        }
      ],
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        {
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            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
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          "scenarios": [
            {
              "lang": "en",
              "value": "AV:L - The vulnerability is reached via open/read on /dev/vcs* character devices (vcs_read), which requires local system access through the VFS syscall path, not network or adjacent network access.\nAC:L - The attacker controls both sides of the race\u2014one thread reading a large buffer from /dev/vcsN and another issuing VT_DISALLOCATE on a VT tty\u2014so success does not depend on conditions outside attacker influence.\nPR:L - Exploitation needs only an unprivileged local account with access to a VT tty and /dev/vcs* (e.g., tty group or console login); VT_DISALLOCATE notably performs no perm/capability check, so real root is not required.\nUI:N - The attacker opens the devices and triggers the race themselves with no action required from another user.\nS:U - This is a standard in-kernel use-after-free enabling privilege escalation within the same kernel security authority, with no VM escape or cross-boundary impact.\nC:H - Use-after-free of the kmalloc-1k vc_data object allows heap spraying so subsequent vcs_size/vcs_read_buf accesses can disclose arbitrary kernel memory to userspace.\nI:H - Kernel UAF of a sprayed slab object enables classic heap exploitation primitives for arbitrary write and control-flow hijacking beyond a mere crash.\nA:H - The UAF reliably produces KASAN-detectable use-after-free faults and can cause kernel oops/panic when the freed vc_data is dereferenced."
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        "dateUpdated": "2026-08-05T09:12:11.113Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
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        {
          "url": "https://git.kernel.org/stable/c/af79ea9a2443016f64d8fd8d72020cc874f0e066"
        },
        {
          "url": "https://git.kernel.org/stable/c/6332f52f44b9776568bf3c0b714ddfb0bb175e78"
        },
        {
          "url": "https://git.kernel.org/stable/c/d0332cbf53dad06a22189cc341391237f4ea6d9f"
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          "url": "https://git.kernel.org/stable/c/55515d7d8743b71b80bfe68e89eb9d92630626ab"
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        {
          "url": "https://git.kernel.org/stable/c/fc9e27f3ba083534b8bbf72ab0f5c810ffdc7d18"
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        },
        {
          "url": "https://git.kernel.org/stable/c/226fae124b2dac217ea5436060d623ff3385bc34"
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      ],
      "title": "vc_screen: move load of struct vc_data pointer in vcs_read() to avoid UAF",
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    "dateReserved": "2025-03-27T16:40:15.737Z",
    "dateUpdated": "2026-08-05T09:12:11.113Z",
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            "lang": "en",
            "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nvc_screen: move load of struct vc_data pointer in vcs_read() to avoid UAF\n\nAfter a call to console_unlock() in vcs_read() the vc_data struct can be\nfreed by vc_deallocate(). Because of that, the struct vc_data pointer\nload must be done at the top of while loop in vcs_read() to avoid a UAF\nwhen vcs_size() is called.\n\nSyzkaller reported a UAF in vcs_size().\n\nBUG: KASAN: use-after-free in vcs_size (drivers/tty/vt/vc_screen.c:215)\nRead of size 4 at addr ffff8881137479a8 by task 4a005ed81e27e65/1537\n\nCPU: 0 PID: 1537 Comm: 4a005ed81e27e65 Not tainted 6.2.0-rc5 #1\nHardware name: Red Hat KVM, BIOS 1.15.0-2.module\nCall Trace:\n  \u003cTASK\u003e\n__asan_report_load4_noabort (mm/kasan/report_generic.c:350)\nvcs_size (drivers/tty/vt/vc_screen.c:215)\nvcs_read (drivers/tty/vt/vc_screen.c:415)\nvfs_read (fs/read_write.c:468 fs/read_write.c:450)\n...\n  \u003c/TASK\u003e\n\nAllocated by task 1191:\n...\nkmalloc_trace (mm/slab_common.c:1069)\nvc_allocate (./include/linux/slab.h:580 ./include/linux/slab.h:720\n     drivers/tty/vt/vt.c:1128 drivers/tty/vt/vt.c:1108)\ncon_install (drivers/tty/vt/vt.c:3383)\ntty_init_dev (drivers/tty/tty_io.c:1301 drivers/tty/tty_io.c:1413\n     drivers/tty/tty_io.c:1390)\ntty_open (drivers/tty/tty_io.c:2080 drivers/tty/tty_io.c:2126)\nchrdev_open (fs/char_dev.c:415)\ndo_dentry_open (fs/open.c:883)\nvfs_open (fs/open.c:1014)\n...\n\nFreed by task 1548:\n...\nkfree (mm/slab_common.c:1021)\nvc_port_destruct (drivers/tty/vt/vt.c:1094)\ntty_port_destructor (drivers/tty/tty_port.c:296)\ntty_port_put (drivers/tty/tty_port.c:312)\nvt_disallocate_all (drivers/tty/vt/vt_ioctl.c:662 (discriminator 2))\nvt_ioctl (drivers/tty/vt/vt_ioctl.c:903)\ntty_ioctl (drivers/tty/tty_io.c:2776)\n...\n\nThe buggy address belongs to the object at ffff888113747800\n  which belongs to the cache kmalloc-1k of size 1024\nThe buggy address is located 424 bytes inside of\n  1024-byte region [ffff888113747800, ffff888113747c00)\n\nThe buggy address belongs to the physical page:\npage:00000000b3fe6c7c refcount:1 mapcount:0 mapping:0000000000000000\n     index:0x0 pfn:0x113740\nhead:00000000b3fe6c7c order:3 compound_mapcount:0 subpages_mapcount:0\n     compound_pincount:0\nanon flags: 0x17ffffc0010200(slab|head|node=0|zone=2|lastcpupid=0x1fffff)\nraw: 0017ffffc0010200 ffff888100042dc0 0000000000000000 dead000000000001\nraw: 0000000000000000 0000000000100010 00000001ffffffff 0000000000000000\npage dumped because: kasan: bad access detected\n\nMemory state around the buggy address:\n  ffff888113747880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb\n  ffff888113747900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb\n\u003e ffff888113747980: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb\n                                   ^\n  ffff888113747a00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb\n  ffff888113747a80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb\n==================================================================\nDisabling lock debugging due to kernel taint"
          },
          {
            "lang": "es",
            "value": "En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: vc_screen: se desplaza la carga del puntero struct vc_data en vcs_read() para evitar un UAF. Tras una llamada a console_unlock() en vcs_read(), la estructura vc_data puede liberarse mediante vc_deallocate(). Por ello, la carga del puntero struct vc_data debe realizarse al principio del bucle while en vcs_read() para evitar un UAF al llamar a vcs_size(). Syzkaller report\u00f3 un UAF en vcs_size(). ERROR: 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:  __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) ...  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 p\u00e1gina volcada porque: kasan: mal acceso detectado Estado de memoria alrededor de la direcci\u00f3n con errores: ffff888113747880: fb fb 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 \u0026gt; 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 ffff888113747a80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ================================================================== Deshabilitar la depuraci\u00f3n de bloqueo debido a una contaminaci\u00f3n del kernel"
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                      "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                      "versionEndExcluding": "4.14.329",
                      "versionStartIncluding": "2.6.38",
                      "vulnerable": true
                    },
                    {
                      "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                      "versionEndExcluding": "4.19.273",
                      "versionStartIncluding": "2.6.38",
                      "vulnerable": true
                    },
                    {
                      "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                      "versionEndExcluding": "5.4.232",
                      "versionStartIncluding": "2.6.38",
                      "vulnerable": true
                    },
                    {
                      "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                      "versionEndExcluding": "5.10.168",
                      "versionStartIncluding": "2.6.38",
                      "vulnerable": true
                    },
                    {
                      "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                      "versionEndExcluding": "5.15.93",
                      "versionStartIncluding": "2.6.38",
                      "vulnerable": true
                    },
                    {
                      "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                      "versionEndExcluding": "6.1.11",
                      "versionStartIncluding": "2.6.38",
                      "vulnerable": true
                    },
                    {
                      "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                      "versionEndExcluding": "6.2",
                      "versionStartIncluding": "2.6.38",
                      "vulnerable": true
                    }
                  ],
                  "negate": false,
                  "operator": "OR"
                }
              ]
            }
          ],
          "descriptions": [
            {
              "lang": "en",
              "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nvc_screen: move load of struct vc_data pointer in vcs_read() to avoid UAF\n\nAfter a call to console_unlock() in vcs_read() the vc_data struct can be\nfreed by vc_deallocate(). Because of that, the struct vc_data pointer\nload must be done at the top of while loop in vcs_read() to avoid a UAF\nwhen vcs_size() is called.\n\nSyzkaller reported a UAF in vcs_size().\n\nBUG: KASAN: use-after-free in vcs_size (drivers/tty/vt/vc_screen.c:215)\nRead of size 4 at addr ffff8881137479a8 by task 4a005ed81e27e65/1537\n\nCPU: 0 PID: 1537 Comm: 4a005ed81e27e65 Not tainted 6.2.0-rc5 #1\nHardware name: Red Hat KVM, BIOS 1.15.0-2.module\nCall Trace:\n  \u003cTASK\u003e\n__asan_report_load4_noabort (mm/kasan/report_generic.c:350)\nvcs_size (drivers/tty/vt/vc_screen.c:215)\nvcs_read (drivers/tty/vt/vc_screen.c:415)\nvfs_read (fs/read_write.c:468 fs/read_write.c:450)\n...\n  \u003c/TASK\u003e\n\nAllocated by task 1191:\n...\nkmalloc_trace (mm/slab_common.c:1069)\nvc_allocate (./include/linux/slab.h:580 ./include/linux/slab.h:720\n     drivers/tty/vt/vt.c:1128 drivers/tty/vt/vt.c:1108)\ncon_install (drivers/tty/vt/vt.c:3383)\ntty_init_dev (drivers/tty/tty_io.c:1301 drivers/tty/tty_io.c:1413\n     drivers/tty/tty_io.c:1390)\ntty_open (drivers/tty/tty_io.c:2080 drivers/tty/tty_io.c:2126)\nchrdev_open (fs/char_dev.c:415)\ndo_dentry_open (fs/open.c:883)\nvfs_open (fs/open.c:1014)\n...\n\nFreed by task 1548:\n...\nkfree (mm/slab_common.c:1021)\nvc_port_destruct (drivers/tty/vt/vt.c:1094)\ntty_port_destructor (drivers/tty/tty_port.c:296)\ntty_port_put (drivers/tty/tty_port.c:312)\nvt_disallocate_all (drivers/tty/vt/vt_ioctl.c:662 (discriminator 2))\nvt_ioctl (drivers/tty/vt/vt_ioctl.c:903)\ntty_ioctl (drivers/tty/tty_io.c:2776)\n...\n\nThe buggy address belongs to the object at ffff888113747800\n  which belongs to the cache kmalloc-1k of size 1024\nThe buggy address is located 424 bytes inside of\n  1024-byte region [ffff888113747800, ffff888113747c00)\n\nThe buggy address belongs to the physical page:\npage:00000000b3fe6c7c refcount:1 mapcount:0 mapping:0000000000000000\n     index:0x0 pfn:0x113740\nhead:00000000b3fe6c7c order:3 compound_mapcount:0 subpages_mapcount:0\n     compound_pincount:0\nanon flags: 0x17ffffc0010200(slab|head|node=0|zone=2|lastcpupid=0x1fffff)\nraw: 0017ffffc0010200 ffff888100042dc0 0000000000000000 dead000000000001\nraw: 0000000000000000 0000000000100010 00000001ffffffff 0000000000000000\npage dumped because: kasan: bad access detected\n\nMemory state around the buggy address:\n  ffff888113747880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb\n  ffff888113747900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb\n\u003e ffff888113747980: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb\n                                   ^\n  ffff888113747a00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb\n  ffff888113747a80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb\n==================================================================\nDisabling lock debugging due to kernel taint"
            }
          ],
          "metrics": [
            {
              "cvssV3_1": {
                "baseScore": 7.8,
                "baseSeverity": "HIGH",
                "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
                "version": "3.1"
              },
              "scenarios": [
                {
                  "lang": "en",
                  "value": "AV:L - The vulnerability is reached via open/read on /dev/vcs* character devices (vcs_read), which requires local system access through the VFS syscall path, not network or adjacent network access.\nAC:L - The attacker controls both sides of the race\u2014one thread reading a large buffer from /dev/vcsN and another issuing VT_DISALLOCATE on a VT tty\u2014so success does not depend on conditions outside attacker influence.\nPR:L - Exploitation needs only an unprivileged local account with access to a VT tty and /dev/vcs* (e.g., tty group or console login); VT_DISALLOCATE notably performs no perm/capability check, so real root is not required.\nUI:N - The attacker opens the devices and triggers the race themselves with no action required from another user.\nS:U - This is a standard in-kernel use-after-free enabling privilege escalation within the same kernel security authority, with no VM escape or cross-boundary impact.\nC:H - Use-after-free of the kmalloc-1k vc_data object allows heap spraying so subsequent vcs_size/vcs_read_buf accesses can disclose arbitrary kernel memory to userspace.\nI:H - Kernel UAF of a sprayed slab object enables classic heap exploitation primitives for arbitrary write and control-flow hijacking beyond a mere crash.\nA:H - The UAF reliably produces KASAN-detectable use-after-free faults and can cause kernel oops/panic when the freed vc_data is dereferenced."
                }
              ]
            }
          ],
          "providerMetadata": {
            "dateUpdated": "2026-08-05T09:12:11.113Z",
            "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "shortName": "Linux"
          },
          "references": [
            {
              "url": "https://git.kernel.org/stable/c/af79ea9a2443016f64d8fd8d72020cc874f0e066"
            },
            {
              "url": "https://git.kernel.org/stable/c/6332f52f44b9776568bf3c0b714ddfb0bb175e78"
            },
            {
              "url": "https://git.kernel.org/stable/c/d0332cbf53dad06a22189cc341391237f4ea6d9f"
            },
            {
              "url": "https://git.kernel.org/stable/c/55515d7d8743b71b80bfe68e89eb9d92630626ab"
            },
            {
              "url": "https://git.kernel.org/stable/c/fc9e27f3ba083534b8bbf72ab0f5c810ffdc7d18"
            },
            {
              "url": "https://git.kernel.org/stable/c/8506f16aae9daf354e3732bcfd447e2a97f023df"
            },
            {
              "url": "https://git.kernel.org/stable/c/226fae124b2dac217ea5436060d623ff3385bc34"
            }
          ],
          "title": "vc_screen: move load of struct vc_data pointer in vcs_read() to avoid UAF",
          "x_generator": {
            "engine": "bippy-1.2.0"
          }
        }
      },
      "cveMetadata": {
        "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "assignerShortName": "Linux",
        "cveId": "CVE-2023-52973",
        "datePublished": "2025-03-27T16:43:12.756Z",
        "dateReserved": "2025-03-27T16:40:15.737Z",
        "dateUpdated": "2026-08-05T09:12:11.113Z",
        "state": "PUBLISHED"
      },
      "dataType": "CVE_RECORD",
      "dataVersion": "5.2"
    }
  }
}



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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

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  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
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  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


Detection rules are retrieved from Rulezet.


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