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vuln-cve/data/2023/53xxx/CVE-2023-53747.json
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{
"dataType": "CVE_RECORD",
"dataVersion": "5.2",
"cveMetadata": {
"cveId": "CVE-2023-53747",
"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"state": "PUBLISHED",
"assignerShortName": "Linux",
"dateReserved": "2025-12-08T01:18:04.279Z",
"datePublished": "2025-12-08T01:19:06.255Z",
"dateUpdated": "2026-10-15T21:41:35.219Z"
},
"containers": {
"cna": {
"providerMetadata": {
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux",
"dateUpdated": "2026-08-05T09:15:45.787Z"
},
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nvc_screen: reload load of struct vc_data pointer in vcs_write() to avoid UAF\n\nAfter a call to console_unlock() in vcs_write() the vc_data struct can be\nfreed by vc_port_destruct(). Because of that, the struct vc_data pointer\nmust be reloaded in the while loop in vcs_write() after console_lock() to\navoid a UAF when vcs_size() is called.\n\nSyzkaller reported a UAF in vcs_size().\n\nBUG: KASAN: slab-use-after-free in vcs_size (drivers/tty/vt/vc_screen.c:215)\nRead of size 4 at addr ffff8880beab89a8 by task repro_vcs_size/4119\n\nCall Trace:\n <TASK>\n__asan_report_load4_noabort (mm/kasan/report_generic.c:380)\nvcs_size (drivers/tty/vt/vc_screen.c:215)\nvcs_write (drivers/tty/vt/vc_screen.c:664)\nvfs_write (fs/read_write.c:582 fs/read_write.c:564)\n...\n <TASK>\n\nAllocated by task 1213:\nkmalloc_trace (mm/slab_common.c:1064)\nvc_allocate (./include/linux/slab.h:559 ./include/linux/slab.h:680\n drivers/tty/vt/vt.c:1078 drivers/tty/vt/vt.c:1058)\ncon_install (drivers/tty/vt/vt.c:3334)\ntty_init_dev (drivers/tty/tty_io.c:1303 drivers/tty/tty_io.c:1415\n drivers/tty/tty_io.c:1392)\ntty_open (drivers/tty/tty_io.c:2082 drivers/tty/tty_io.c:2128)\nchrdev_open (fs/char_dev.c:415)\ndo_dentry_open (fs/open.c:921)\nvfs_open (fs/open.c:1052)\n...\n\nFreed by task 4116:\nkfree (mm/slab_common.c:1016)\nvc_port_destruct (drivers/tty/vt/vt.c:1044)\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:2778)\n...\n\nThe buggy address belongs to the object at ffff8880beab8800\n which belongs to the cache kmalloc-1k of size 1024\nThe buggy address is located 424 bytes inside of\n freed 1024-byte region [ffff8880beab8800, ffff8880beab8c00)\n\nThe buggy address belongs to the physical page:\npage:00000000afc77580 refcount:1 mapcount:0 mapping:0000000000000000\n index:0x0 pfn:0xbeab8\nhead:00000000afc77580 order:3 entire_mapcount:0 nr_pages_mapped:0\n pincount:0\nflags: 0xfffffc0010200(slab|head|node=0|zone=1|lastcpupid=0x1fffff)\npage_type: 0xffffffff()\nraw: 000fffffc0010200 ffff888100042dc0 ffffea000426de00 dead000000000002\nraw: 0000000000000000 0000000000100010 00000001ffffffff 0000000000000000\npage dumped because: kasan: bad access detected\n\nMemory state around the buggy address:\n ffff8880beab8880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb\n ffff8880beab8900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb\n>ffff8880beab8980: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb\n ^\n ffff8880beab8a00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb\n ffff8880beab8a80: 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": {
"version": "3.1",
"vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
"baseScore": 7.8,
"baseSeverity": "HIGH"
},
"scenarios": [
{
"lang": "en",
"value": "AV:L - Exploitation requires local access to character device nodes — write(2) on /dev/vcsN or /dev/vcsaN and an ioctl on a VT tty for VT_DISALLOCATE. There is no network or remote-peer reachability.\nAC:L - The attacker controls both sides of the race: one thread drives the write loop (which unconditionally drops console_lock every PAGE_SIZE chunk) while another calls VT_DISALLOCATE, and the window can be stretched indefinitely by backing the user buffer with userfaultfd or FUSE so copy_from_user stalls on demand. This makes the free-and-respray step reliable rather than opportunistic.\nPR:L - VT_DISALLOCATE carries no perm or capable() check whatsoever in vt_ioctl, so the only gate is DAC on /dev/vcs* and a VT fd — held by any tty-group member, any console-logged-in user via logind ACLs, or non-root console services on embedded systems. No capability or root privilege in the initial namespace is needed.\nUI:N - The attacker performs every step — allocating the VT, opening /dev/vcs*, issuing the write and the deallocation ioctl — from its own threads. No victim action is involved.\nS:U - The use-after-free corrupts kernel heap memory within the same kernel security authority; no VM, IOMMU, or sandbox boundary is crossed.\nC:H - The stale vc_data is read after free (vcs_size, screenpos, vc_sw), and since the attacker can reclaim the kmalloc-1k slot with controlled data and set vc->vc_origin arbitrarily, the write path's read-modify-write sequences (vcs_scr_readw on the computed pointer) yield an arbitrary kernel-memory read primitive.\nI:H - vcs_write_buf derives its destination pointer from the freed object's vc_origin/vc_visible_origin and then writes attacker-supplied 16-bit values there, giving a controlled arbitrary kernel write; the viewed path additionally makes an indirect call through vc->vc_sw->con_screen_pos read out of freed memory, a direct control-flow hijack primitive leading to privilege escalation.\nA:H - Even unweaponized the bug is a slab use-after-free that reads and writes through a dangling pointer, producing KASAN splats, oopses, and kernel panics as syzkaller demonstrated, and it can be retriggered at will."
}
]
}
],
"affected": [
{
"product": "Linux",
"vendor": "Linux",
"defaultStatus": "unaffected",
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"programFiles": [
"drivers/tty/vt/vc_screen.c"
],
"versions": [
{
"version": "ac751efa6a0d70f2c9daef5c7e3a92270f5c2dff",
"lessThan": "934de9a9b659785fed3e820bc0c813a460c71fea",
"status": "affected",
"versionType": "git"
},
{
"version": "ac751efa6a0d70f2c9daef5c7e3a92270f5c2dff",
"lessThan": "0deff678157333d775af190f84696336cdcccd6d",
"status": "affected",
"versionType": "git"
},
{
"version": "ac751efa6a0d70f2c9daef5c7e3a92270f5c2dff",
"lessThan": "a4e3c4c65ae8510e01352c9a4347e05c035b2ce2",
"status": "affected",
"versionType": "git"
},
{
"version": "ac751efa6a0d70f2c9daef5c7e3a92270f5c2dff",
"lessThan": "11dddfbb7a4e62489b01074d6c04d9d1b42e4047",
"status": "affected",
"versionType": "git"
},
{
"version": "ac751efa6a0d70f2c9daef5c7e3a92270f5c2dff",
"lessThan": "e3d1adcad5b73c7ed0c7edb35ab68abcaa45cf67",
"status": "affected",
"versionType": "git"
},
{
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"lessThan": "3338d0b9acde770ee588eead5cac32c25e7048fc",
"status": "affected",
"versionType": "git"
},
{
"version": "ac751efa6a0d70f2c9daef5c7e3a92270f5c2dff",
"lessThan": "1de42e7653d6714a7507ba6696151a1fa028c69f",
"status": "affected",
"versionType": "git"
},
{
"version": "ac751efa6a0d70f2c9daef5c7e3a92270f5c2dff",
"lessThan": "8fb9ea65c9d1338b0d2bb0a9122dc942cdd32357",
"status": "affected",
"versionType": "git"
}
]
},
{
"product": "Linux",
"vendor": "Linux",
"defaultStatus": "affected",
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"programFiles": [
"drivers/tty/vt/vc_screen.c"
],
"versions": [
{
"version": "2.6.38",
"status": "affected"
},
{
"version": "0",
"lessThan": "2.6.38",
"status": "unaffected",
"versionType": "semver"
},
{
"version": "4.14.327",
"lessThanOrEqual": "4.14.*",
"status": "unaffected",
"versionType": "semver"
},
{
"version": "4.19.284",
"lessThanOrEqual": "4.19.*",
"status": "unaffected",
"versionType": "semver"
},
{
"version": "5.4.244",
"lessThanOrEqual": "5.4.*",
"status": "unaffected",
"versionType": "semver"
},
{
"version": "5.10.181",
"lessThanOrEqual": "5.10.*",
"status": "unaffected",
"versionType": "semver"
},
{
"version": "5.15.113",
"lessThanOrEqual": "5.15.*",
"status": "unaffected",
"versionType": "semver"
},
{
"version": "6.1.30",
"lessThanOrEqual": "6.1.*",
"status": "unaffected",
"versionType": "semver"
},
{
"version": "6.3.4",
"lessThanOrEqual": "6.3.*",
"status": "unaffected",
"versionType": "semver"
},
{
"version": "6.4",
"lessThanOrEqual": "*",
"status": "unaffected",
"versionType": "original_commit_for_fix"
}
]
}
],
"cpeApplicability": [
{
"nodes": [
{
"operator": "OR",
"negate": false,
"cpeMatch": [
{
"vulnerable": true,
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionStartIncluding": "2.6.38",
"versionEndExcluding": "4.14.327"
},
{
"vulnerable": true,
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionStartIncluding": "2.6.38",
"versionEndExcluding": "4.19.284"
},
{
"vulnerable": true,
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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},
{
"vulnerable": true,
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionStartIncluding": "2.6.38",
"versionEndExcluding": "5.10.181"
},
{
"vulnerable": true,
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionStartIncluding": "2.6.38",
"versionEndExcluding": "5.15.113"
},
{
"vulnerable": true,
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionStartIncluding": "2.6.38",
"versionEndExcluding": "6.1.30"
},
{
"vulnerable": true,
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionStartIncluding": "2.6.38",
"versionEndExcluding": "6.3.4"
},
{
"vulnerable": true,
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionStartIncluding": "2.6.38",
"versionEndExcluding": "6.4"
}
]
}
]
}
],
"references": [
{
"url": "https://git.kernel.org/stable/c/934de9a9b659785fed3e820bc0c813a460c71fea"
},
{
"url": "https://git.kernel.org/stable/c/0deff678157333d775af190f84696336cdcccd6d"
},
{
"url": "https://git.kernel.org/stable/c/a4e3c4c65ae8510e01352c9a4347e05c035b2ce2"
},
{
"url": "https://git.kernel.org/stable/c/11dddfbb7a4e62489b01074d6c04d9d1b42e4047"
},
{
"url": "https://git.kernel.org/stable/c/e3d1adcad5b73c7ed0c7edb35ab68abcaa45cf67"
},
{
"url": "https://git.kernel.org/stable/c/3338d0b9acde770ee588eead5cac32c25e7048fc"
},
{
"url": "https://git.kernel.org/stable/c/1de42e7653d6714a7507ba6696151a1fa028c69f"
},
{
"url": "https://git.kernel.org/stable/c/8fb9ea65c9d1338b0d2bb0a9122dc942cdd32357"
}
],
"title": "vc_screen: reload load of struct vc_data pointer in vcs_write() to avoid UAF",
"x_generator": {
"engine": "bippy-1.2.0"
}
},
"adp": [
{
"metrics": [
{
"other": {
"type": "ssvc",
"content": {
"id": "CVE-2023-53747",
"role": "CISA Coordinator",
"options": [
{
"Exploitation": "none"
},
{
"Automatable": "no"
},
{
"Technical Impact": "total"
}
],
"version": "2.0.3",
"timestamp": "2026-10-15T21:36:57.834897Z"
}
}
}
],
"title": "CISA ADP Vulnrichment",
"providerMetadata": {
"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"shortName": "CISA-ADP",
"dateUpdated": "2026-10-15T21:41:35.219Z"
}
}
]
}
}