CVE-2026-63794
published 2026-07-19CVE-2026-63794: In the Linux kernel, the following vulnerability has been resolved: KVM: SVM: Fix page overflow in sev_dbg_crypt() for ENCRYPT path In sev_dbg_crypt(), the…
PriorityP340high7.8CVSS 3.1
AVLACLPRLUINSUCHIHAH
EPSS
0.14%
4.0th percentile
In the Linux kernel, the following vulnerability has been resolved:
KVM: SVM: Fix page overflow in sev_dbg_crypt() for ENCRYPT path
In sev_dbg_crypt(), the per-iteration transfer length is bounded by
the source page offset (PAGE_SIZE - s_off) but not by the destination
page offset (PAGE_SIZE - d_off). When d_off > s_off, the encrypt
path (__sev_dbg_encrypt_user) performs a read-modify-write using a
single-page intermediate buffer (dst_tpage):
1. __sev_dbg_decrypt() expands the size to round_up(len + (d_off & 15), 16)
before issuing the PSP command. If len + (d_off & 15) > PAGE_SIZE,
the PSP writes beyond the end of the 4096-byte dst_tpage allocation.
2. The subsequent memcpy()/copy_from_user() into
page_address(dst_tpage) + (d_off & 15) of 'len' bytes overflows
by up to 15 bytes under the same condition.
Trigger example: s_off = 0, d_off = 1, debug.len = PAGE_SIZE -
the PSP is instructed to write round_up(4097, 16) = 4112 bytes to
a 4096-byte buffer.
Fix by also bounding len by (PAGE_SIZE - d_off), the same check that
sev_send_update_data() already performs for its single-page guest
region.
BUG: KASAN: slab-use-after-free in sev_dbg_crypt+0x993/0xd10 [kvm_amd]
Write of size 4095 at addr ff110062293bb009 by task sev_dbg_test/228214
CPU: 96 UID: 0 PID: 228214 Comm: sev_dbg_test Tainted: G U W 7.0.0-smp--5ce9b0c48211-dbg #156 PREEMPTLAZY
Tainted: [U]=USER, [W]=WARN
Hardware name: Google Astoria/astoria, BIOS 0.20250817.1-0 08/25/2025
Call Trace:
dump_stack_lvl+0x54/0x70
print_report+0xbc/0x260
kasan_report+0xa2/0xd0
kasan_check_range+0x25f/0x2c0
__asan_memcpy+0x40/0x70
sev_dbg_crypt+0x993/0xd10 [kvm_amd]
sev_mem_enc_ioctl+0x33c/0x450 [kvm_amd]
kvm_vm_ioctl+0x65d/0x6d0 [kvm]
__se_sys_ioctl+0xb2/0x100
do_syscall_64+0xe8/0x870
entry_SYSCALL_64_after_hwframe+0x4b/0x53
The buggy address belongs to the physical page:
page: refcount:1 mapcount:0 mapping:0000000000000000 index:0x7fe72b6a0 pfn:0x62293bb
memcg:ff11000112827d82
flags: 0x1400000000000000(node=1|zone=1)
Affected
17 ranges
| Vendor | Product | Version range | Fixed in |
|---|---|---|---|
| linux | linux | — | — |
| linux | linux | >= 24f41fb23a39bc2b6f190dcef35a5813a4bf183a < f701ae476cb92a3a3d8844bb39bb63b4512684c8 | f701ae476cb92a3a3d8844bb39bb63b4512684c8 |
| linux | linux | >= 24f41fb23a39bc2b6f190dcef35a5813a4bf183a < 64f2449841ffc7d203183aa4c748c9c77951ecc5 | 64f2449841ffc7d203183aa4c748c9c77951ecc5 |
| linux | linux | >= 24f41fb23a39bc2b6f190dcef35a5813a4bf183a < 9349b50f4b11f135fe73b56cb2c2c872d8bc71d7 | 9349b50f4b11f135fe73b56cb2c2c872d8bc71d7 |
| linux | linux | >= 24f41fb23a39bc2b6f190dcef35a5813a4bf183a < 889c2a9c59897ca912bf39df5bb92555a0a13df4 | 889c2a9c59897ca912bf39df5bb92555a0a13df4 |
| linux | linux | >= 24f41fb23a39bc2b6f190dcef35a5813a4bf183a < e1a0fe288dee07b7da25a71e007c1ecd1080315b | e1a0fe288dee07b7da25a71e007c1ecd1080315b |
| linux | linux | >= 24f41fb23a39bc2b6f190dcef35a5813a4bf183a < 720949ed666f34ff28ffdfe1471a5861d1e41fdf | 720949ed666f34ff28ffdfe1471a5861d1e41fdf |
| linux | linux | >= 24f41fb23a39bc2b6f190dcef35a5813a4bf183a < 2753a097d1fe24c4351c608048612c74108aa89f | 2753a097d1fe24c4351c608048612c74108aa89f |
| linux | linux | >= 24f41fb23a39bc2b6f190dcef35a5813a4bf183a < 78ee2d50185a037b3d2452a97f3dad69c3f7f389 | 78ee2d50185a037b3d2452a97f3dad69c3f7f389 |
| linux | linux_kernel | — | — |
| linux | linux_kernel | >= 4.16 < 5.10.260 | 5.10.260 |
| linux | linux_kernel | >= 5.11 < 5.15.211 | 5.15.211 |
| linux | linux_kernel | >= 5.16 < 6.1.177 | 6.1.177 |
| linux | linux_kernel | >= 6.13 < 6.18.38 | 6.18.38 |
| linux | linux_kernel | >= 6.19 < 7.1.3 | 7.1.3 |
| linux | linux_kernel | >= 6.2 < 6.6.144 | 6.6.144 |
| linux | linux_kernel | >= 6.7 < 6.12.95 | 6.12.95 |
CVSS provenance
nvdv3.17.8HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
vendor_redhat7.0HIGH
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Red Hat
kernel: KVM: SVM: Fix page overflow in sev_dbg_crypt() for ENCRYPT path
vendor_redhat·2026-07-19·CVSS 7.0
CVE-2026-63794 [HIGH] CWE-805 kernel: KVM: SVM: Fix page overflow in sev_dbg_crypt() for ENCRYPT path
kernel: KVM: SVM: Fix page overflow in sev_dbg_crypt() for ENCRYPT path
In the Linux kernel, the following vulnerability has been resolved:
KVM: SVM: Fix page overflow in sev_dbg_crypt() for ENCRYPT path
In sev_dbg_crypt(), the per-iteration transfer length is bounded by
the source page offset (PAGE_SIZE - s_off) but not by the destination
page offset (PAGE_SIZE - d_off). When d_off > s_off, the encrypt
path (__sev_dbg_encrypt_user) performs a read-modify-write using a
single-page intermediate buffer (dst_tpage):
1. __sev_dbg_decrypt() expands the size to round_up(len + (d_off & 15), 16)
before issuing the PSP command. If len + (d_off & 15) > PAGE_SIZE,
the PSP writes beyond the end of the 4096-byte dst_tpage allocation.
2. The subsequent memcpy()/copy_from_user() into
page_address(dst_tp
GHSA
In the Linux kernel, the following vulnerability has been resolved: KVM: SVM: Fix page overflow in sev_dbg_crypt() for ENCRYPT path In sev_dbg_crypt(), the per-iteration transfer length is bounded b
ghsa_unreviewed·2026-07-19
CVE-2026-63794 In the Linux kernel, the following vulnerability has been resolved: KVM: SVM: Fix page overflow in sev_dbg_crypt() for ENCRYPT path In sev_dbg_crypt(), the per-iteration transfer length is bounded b
In the Linux kernel, the following vulnerability has been resolved:
KVM: SVM: Fix page overflow in sev_dbg_crypt() for ENCRYPT path
In sev_dbg_crypt(), the per-iteration transfer length is bounded by
the source page offset (PAGE_SIZE - s_off) but not by the destination
page offset (PAGE_SIZE - d_off). When d_off > s_off, the encrypt
path (__sev_dbg_encrypt_user) performs a read-modify-write using a
single-page intermediate buffer (dst_tpage):
1. __sev_dbg_decrypt() expands the size to round_up(len + (d_off & 15), 16)
before issuing the PSP command. If len + (d_off & 15) > PAGE_SIZE,
the PSP writes beyond the end of the 4096-byte dst_tpage allocation.
2. The subsequent memcpy()/copy_from_user() into
page_address(dst_tpage) + (d_off & 15) of 'len' bytes overflows
by up to 15 bytes under
No detection rules found.
No public exploits indexed.
https://git.kernel.org/stable/c/2753a097d1fe24c4351c608048612c74108aa89fhttps://git.kernel.org/stable/c/64f2449841ffc7d203183aa4c748c9c77951ecc5https://git.kernel.org/stable/c/720949ed666f34ff28ffdfe1471a5861d1e41fdfhttps://git.kernel.org/stable/c/78ee2d50185a037b3d2452a97f3dad69c3f7f389https://git.kernel.org/stable/c/889c2a9c59897ca912bf39df5bb92555a0a13df4https://git.kernel.org/stable/c/9349b50f4b11f135fe73b56cb2c2c872d8bc71d7https://git.kernel.org/stable/c/e1a0fe288dee07b7da25a71e007c1ecd1080315bhttps://git.kernel.org/stable/c/f701ae476cb92a3a3d8844bb39bb63b4512684c8
2026-07-19
Published