Answer in brief
CVE-2026-63794 records a Unknown severity vulnerability in KVM: SVM: Fix page overflow in sev_dbg_crypt() for ENCRYPT path. The current sources do not mark it as known exploited. The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
Answer in brief
CVE-2026-63794 records a Unknown severity vulnerability in KVM: SVM: Fix page overflow in sev_dbg_crypt() for ENCRYPT path. The current sources do not mark it as known exploited. The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
A CVSS score is not reported in the current record. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| Linux/Linuxgeneric | >=24f41fb23a39bc2b6f190dcef35a5813a4bf183a <f701ae476cb92a3a3d8844bb39bb63b4512684c8 || >=24f41fb23a39bc2b6f190dcef35a5813a4bf183a <64f2449841ffc7d203183aa4c748c9c77951ecc5 || >=24f41fb23a39bc2b6f190dcef35a5813a4bf183a <9349b50f4b11f135fe73b56cb2c2c872d8bc71d7 || >=24f41fb23a39bc2b6f190dcef35a5813a4bf183a <889c2a9c59897ca912bf39df5bb92555a0a13df4 || >=24f41fb23a39bc2b6f190dcef35a5813a4bf183a <e1a0fe288dee07b7da25a71e007c1ecd1080315b || >=24f41fb23a39bc2b6f190dcef35a5813a4bf183a <720949ed666f34ff28ffdfe1471a5861d1e41fdf || >=24f41fb23a39bc2b6f190dcef35a5813a4bf183a <2753a097d1fe24c4351c608048612c74108aa89f || >=24f41fb23a39bc2b6f190dcef35a5813a4bf183a <78ee2d50185a037b3d2452a97f3dad69c3f7f389 | f701ae476cb92a3a3d8844bb39bb63b4512684c8, 64f2449841ffc7d203183aa4c748c9c77951ecc5, 9349b50f4b11f135fe73b56cb2c2c872d8bc71d7, 889c2a9c59897ca912bf39df5bb92555a0a13df4, e1a0fe288dee07b7da25a71e007c1ecd1080315b, 720949ed666f34ff28ffdfe1471a5861d1e41fdf, 2753a097d1fe24c4351c608048612c74108aa89f, 78ee2d50185a037b3d2452a97f3dad69c3f7f389 |
| Linux/Linuxgeneric | 4.16 | Not reported |
Published upstream
Jul 19, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Aug 17, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Aug 17, 2026
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: <TASK> 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 </TASK> 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) raw: 1400000000000000 0000000000000000 dead000000000122 0000000000000000 raw: 00000007fe72b6a0 0000000000000000 00000001ffffffff ff11000112827d82 page dumped because: kasan: bad access detected Memory state around the buggy address: ff110062293bbf00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ff110062293bbf80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 >ff110062293bc000: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc ^ ff110062293bc080: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc ff110062293bc100: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc ================================================================== Disabling lock debugging due to kernel taint [sean: add sample KASAN splat, Fixes, and stable@]
Quoted source text, attributed separately from HOL analysis.
A CVSS score is not reported in the current record. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| Linux/Linuxgeneric | >=24f41fb23a39bc2b6f190dcef35a5813a4bf183a <f701ae476cb92a3a3d8844bb39bb63b4512684c8 || >=24f41fb23a39bc2b6f190dcef35a5813a4bf183a <64f2449841ffc7d203183aa4c748c9c77951ecc5 || >=24f41fb23a39bc2b6f190dcef35a5813a4bf183a <9349b50f4b11f135fe73b56cb2c2c872d8bc71d7 || >=24f41fb23a39bc2b6f190dcef35a5813a4bf183a <889c2a9c59897ca912bf39df5bb92555a0a13df4 || >=24f41fb23a39bc2b6f190dcef35a5813a4bf183a <e1a0fe288dee07b7da25a71e007c1ecd1080315b || >=24f41fb23a39bc2b6f190dcef35a5813a4bf183a <720949ed666f34ff28ffdfe1471a5861d1e41fdf || >=24f41fb23a39bc2b6f190dcef35a5813a4bf183a <2753a097d1fe24c4351c608048612c74108aa89f || >=24f41fb23a39bc2b6f190dcef35a5813a4bf183a <78ee2d50185a037b3d2452a97f3dad69c3f7f389 | f701ae476cb92a3a3d8844bb39bb63b4512684c8, 64f2449841ffc7d203183aa4c748c9c77951ecc5, 9349b50f4b11f135fe73b56cb2c2c872d8bc71d7, 889c2a9c59897ca912bf39df5bb92555a0a13df4, e1a0fe288dee07b7da25a71e007c1ecd1080315b, 720949ed666f34ff28ffdfe1471a5861d1e41fdf, 2753a097d1fe24c4351c608048612c74108aa89f, 78ee2d50185a037b3d2452a97f3dad69c3f7f389 |
| Linux/Linuxgeneric | 4.16 | Not reported |
Published upstream
Jul 19, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Aug 17, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Aug 17, 2026
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: <TASK> 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 </TASK> 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) raw: 1400000000000000 0000000000000000 dead000000000122 0000000000000000 raw: 00000007fe72b6a0 0000000000000000 00000001ffffffff ff11000112827d82 page dumped because: kasan: bad access detected Memory state around the buggy address: ff110062293bbf00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ff110062293bbf80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 >ff110062293bc000: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc ^ ff110062293bc080: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc ff110062293bc100: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc ================================================================== Disabling lock debugging due to kernel taint [sean: add sample KASAN splat, Fixes, and stable@]
Quoted source text, attributed separately from HOL analysis.