{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2025-40322", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2025-04-16T07:20:57.186Z", "datePublished": "2025-12-08T00:46:49.773Z", "dateUpdated": "2026-08-05T12:09:35.122Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T12:09:35.122Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nfbdev: bitblit: bound-check glyph index in bit_putcs*\n\nbit_putcs_aligned()/unaligned() derived the glyph pointer from the\ncharacter value masked by 0xff/0x1ff, which may exceed the actual font's\nglyph count and read past the end of the built-in font array.\nClamp the index to the actual glyph count before computing the address.\n\nThis fixes a global out-of-bounds read reported by syzbot." } ], "metrics": [ { "cvssV3_1": { "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" }, "scenarios": [ { "lang": "en", "value": "AV:L - The vulnerable render path is reached only through local interfaces — `KDFONTOP` ioctl on a VT plus writes to `/dev/vcsa*` or the tty itself. There is no remote or adjacent-network exposure of fbcon.\nAC:L - The attacker fully controls both the desync (choosing font dimensions that make `vc_do_resize()` fail deterministically via `new_screen_size > KMALLOC_MAX_SIZE` or `!new_screen_size`) and the trigger (writing glyph indices 256–511 into the screen buffer); syzbot has a working C reproducer.\nPR:L - `KDFONTOP(KD_FONT_OP_SET)` and `PIO_UNIMAP` only require `perm`, which is granted to any unprivileged user whose controlling tty is the VT (`current->signal->tty == tty`) — no capability is needed, and `vcs_open()` performs no capability check at all.\nUI:N - The attacker performs the font ioctl and the console write entirely from its own process; no victim action or cooperation is needed.\nS:U - The out-of-bounds read stays within the kernel's own memory and the impact is confined to the kernel security authority; no VM, IOMMU, or sandbox boundary is crossed.\nC:H - Up to 256 glyph cells are read past the font array — 4 KB beyond the global `fontdata_8x16`, or up to ~256 KB beyond a large user-supplied font — and those raw kernel bytes are blitted to the framebuffer as bitmaps that the attacker can read back via `/dev/fb0`, yielding a substantial kernel memory disclosure primitive.\nI:N - The defect is strictly an out-of-bounds read; the fetched bytes are copied into correctly sized pixmap and attribute buffers, so no kernel memory is modified and no write or control-flow primitive is produced.\nA:H - When the active font is a large kvmalloc-backed user font, the overrun can run hundreds of kilobytes past the allocation into a vmalloc guard page, faulting inside `bit_putcs()` while `console_lock` is held and oopsing/hanging the system; on KASAN builds it trips a report that can panic." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "drivers/video/fbdev/core/bitblit.c" ], "versions": [ { "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "lessThan": "a10cede006f9614b465cf25609a8753efbfd45cc", "status": "affected", "versionType": "git" }, { "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "lessThan": "0998a6cb232674408a03e8561dc15aa266b2f53b", "status": "affected", "versionType": "git" }, { "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "lessThan": "db5c9a162d2f42bcc842b76b3d935dcc050a0eec", "status": "affected", "versionType": "git" }, { "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "lessThan": "c12003bf91fdff381c55ef54fef3e961a5af2545", "status": "affected", "versionType": "git" }, { "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "lessThan": "9ba1a7802ca9a2590cef95b253e6526f4364477f", "status": "affected", "versionType": "git" }, { "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "lessThan": "901f44227072be60812fe8083e83e1533c04eed1", "status": "affected", "versionType": "git" }, { "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "lessThan": "efaf89a75a29b2d179bf4fe63ca62852e93ad620", "status": "affected", "versionType": "git" }, { "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "lessThan": "18c4ef4e765a798b47980555ed665d78b71aeadf", "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/video/fbdev/core/bitblit.c" ], "versions": [ { "version": "2.6.12", "status": "affected" }, { "version": "0", "lessThan": "2.6.12", "status": "unaffected", "versionType": "semver" }, { "version": "5.4.302", "lessThanOrEqual": "5.4.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.10.247", "lessThanOrEqual": "5.10.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.15.197", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.159", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.117", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.58", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.17.8", "lessThanOrEqual": "6.17.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.18", "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": "2.6.12", "versionEndExcluding": "5.4.302" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.12", "versionEndExcluding": "5.10.247" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.12", "versionEndExcluding": "5.15.197" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.12", "versionEndExcluding": "6.1.159" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.12", "versionEndExcluding": "6.6.117" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.12", "versionEndExcluding": "6.12.58" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.12", "versionEndExcluding": "6.17.8" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.12", "versionEndExcluding": "6.18" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/a10cede006f9614b465cf25609a8753efbfd45cc" }, { "url": "https://git.kernel.org/stable/c/0998a6cb232674408a03e8561dc15aa266b2f53b" }, { "url": "https://git.kernel.org/stable/c/db5c9a162d2f42bcc842b76b3d935dcc050a0eec" }, { "url": "https://git.kernel.org/stable/c/c12003bf91fdff381c55ef54fef3e961a5af2545" }, { "url": "https://git.kernel.org/stable/c/9ba1a7802ca9a2590cef95b253e6526f4364477f" }, { "url": "https://git.kernel.org/stable/c/901f44227072be60812fe8083e83e1533c04eed1" }, { "url": "https://git.kernel.org/stable/c/efaf89a75a29b2d179bf4fe63ca62852e93ad620" }, { "url": "https://git.kernel.org/stable/c/18c4ef4e765a798b47980555ed665d78b71aeadf" } ], "title": "fbdev: bitblit: bound-check glyph index in bit_putcs*", "x_generator": { "engine": "bippy-1.2.0" } }, "adp": [ { "metrics": [ { "other": { "type": "ssvc", "content": { "timestamp": "2026-06-16T19:33:40.857434Z", "id": "CVE-2025-40322", "options": [ { "Exploitation": "none" }, { "Automatable": "no" }, { "Technical Impact": "partial" } ], "role": "CISA Coordinator", "version": "2.0.3" } } } ], "title": "CISA ADP Vulnrichment", "providerMetadata": { "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-06-16T19:34:17.887Z" } } ] } }