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CVE-2026-63794— KVM: SVM: Fix page overflow in sev_dbg_crypt() for ENCRYPT path

Quick assessment

Affected
Linux Linux
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Linux kernel是美国Linux基金会开源的一款操作系统内核。 Linux kernel 4.16版本存在安全漏洞，该漏洞源于sev_dbg_crypt函数在ENCRYPT路径中未使用目标页面偏移量限制单次迭代传输长度，可能导致页溢出。

AI Predicted 6.5 Difficulty: Moderate EPSS 0.14% · P4

Possible ATT&CK Techniques 1 AI

T1203 · Exploitation for Client Execution

Affected Version Matrix 18

VendorProduct Version RangeStatus
Linux Linux 24f41fb23a39bc2b6f190dcef35a5813a4bf183a< f701ae476cb92a3a3d8844bb39bb63b4512684c8 affected
24f41fb23a39bc2b6f190dcef35a5813a4bf183a< 64f2449841ffc7d203183aa4c748c9c77951ecc5 affected
24f41fb23a39bc2b6f190dcef35a5813a4bf183a< 9349b50f4b11f135fe73b56cb2c2c872d8bc71d7 affected
24f41fb23a39bc2b6f190dcef35a5813a4bf183a< 889c2a9c59897ca912bf39df5bb92555a0a13df4 affected
24f41fb23a39bc2b6f190dcef35a5813a4bf183a< e1a0fe288dee07b7da25a71e007c1ecd1080315b affected
24f41fb23a39bc2b6f190dcef35a5813a4bf183a< 720949ed666f34ff28ffdfe1471a5861d1e41fdf affected
24f41fb23a39bc2b6f190dcef35a5813a4bf183a< 2753a097d1fe24c4351c608048612c74108aa89f affected
24f41fb23a39bc2b6f190dcef35a5813a4bf183a< 78ee2d50185a037b3d2452a97f3dad69c3f7f389 affected
… +10 more rows
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I. Basic Information for CVE-2026-63794

Vulnerability Information
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Vulnerability Title
KVM: SVM: Fix page overflow in sev_dbg_crypt() for ENCRYPT path
Source: CVE Program / CVE List V5
Vulnerability Description
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@]
Source: CVE Program / CVE List V5
CVSS Information
N/A
Source: CVE Program / CVE List V5
Vulnerability Type
N/A
Source: CVE Program / CVE List V5
Vulnerability Title
Linux kernel 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Linux kernel是美国Linux基金会开源的一款操作系统内核。 Linux kernel 4.16版本存在安全漏洞，该漏洞源于sev_dbg_crypt函数在ENCRYPT路径中未使用目标页面偏移量限制单次迭代传输长度，可能导致页溢出。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
Linux Linux 24f41fb23a39bc2b6f190dcef35a5813a4bf183a ~ f701ae476cb92a3a3d8844bb39bb63b4512684c8 -
Linux Linux 4.16 -

II. Public POCs for CVE-2026-63794

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III. Intelligence Information for CVE-2026-63794

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Patches & Fixes for CVE-2026-63794 (8)

Same Patch Batch · Linux · 2026-07-19 · 429 CVEs total

CVE-2026-63795 10.0 CRITICAL 9p: avoid putting oldfid in p9_client_walk() error path
CVE-2026-64046 9.8 CRITICAL net: tls: prevent chain-after-chain in plain text SG
CVE-2026-63984 9.8 CRITICAL ipv6: rpl: fix hdrlen overflow in ipv6_rpl_srh_decompress()
CVE-2026-63800 9.8 CRITICAL pNFS: Fix use-after-free in pnfs_update_layout()
CVE-2026-63979 9.8 CRITICAL net/handshake: hand off the pinned file reference to accept_doit
CVE-2026-64142 9.8 CRITICAL ksmbd: close durable scavenger races against m_fp_list lookups
CVE-2026-63978 9.8 CRITICAL net/handshake: Drain pending requests at net namespace exit
CVE-2026-64056 9.8 CRITICAL net: ethernet: cortina: Make RX SKB per-port
CVE-2026-63808 9.8 CRITICAL exfat: fix potential use-after-free in exfat_find_dir_entry()
CVE-2026-64055 9.8 CRITICAL net: ethernet: cortina: Carry over frag counter
CVE-2026-63922 9.8 CRITICAL ipv6: exthdrs: refresh nh after handling HAO option
CVE-2026-64033 9.8 CRITICAL RDMA/rtrs: Fix use-after-free in path file creation cleanup
CVE-2026-64113 9.8 CRITICAL ixgbevf: fix use-after-free in VEPA multicast source pruning
CVE-2026-63825 9.8 CRITICAL gcov: use atomic counter updates to fix concurrent access crashes
CVE-2026-64016 9.8 CRITICAL ksmbd: fix durable reconnect error path file lifetime
CVE-2026-64122 9.8 CRITICAL net/mlx5e: Fix use-after-free in mlx5e_tx_reporter_timeout_recover
CVE-2026-64047 9.8 CRITICAL net: tls: fix off-by-one in sg_chain entry count for wrapped sk_msg ring
CVE-2026-64035 9.8 CRITICAL igc: set tx buffer type for SMD frames
CVE-2026-64025 9.8 CRITICAL bpf, skmsg: fix verdict sk_data_ready racing with ktls rx
CVE-2026-64150 9.8 CRITICAL netfilter: nft_inner: release local_lock before re-enabling softirqs

Showing top 20 of 429 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

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