{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2025-39967", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2025-04-16T07:20:57.149Z", "datePublished": "2025-10-15T07:55:51.554Z", "dateUpdated": "2026-08-05T12:06:36.336Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T12:06:36.336Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nfbcon: fix integer overflow in fbcon_do_set_font\n\nFix integer overflow vulnerabilities in fbcon_do_set_font() where font\nsize calculations could overflow when handling user-controlled font\nparameters.\n\nThe vulnerabilities occur when:\n1. CALC_FONTSZ(h, pitch, charcount) performs h * pith * charcount\n multiplication with user-controlled values that can overflow.\n2. FONT_EXTRA_WORDS * sizeof(int) + size addition can also overflow\n3. This results in smaller allocations than expected, leading to buffer\n overflows during font data copying.\n\nAdd explicit overflow checking using check_mul_overflow() and\ncheck_add_overflow() kernel helpers to safety validate all size\ncalculations before allocation." } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H", "baseScore": 7.8, "baseSeverity": "HIGH" }, "scenarios": [ { "lang": "en", "value": "AV:L - The only route to `fbcon_set_font()` is the `KDFONTOP` ioctl on a virtual console device (`/dev/ttyN`, `/dev/tty`), reached through `vt_ioctl()`/`con_font_op()`; there is no network, packet, or remote-peer input into this code.\nAC:L - The attacker supplies every operand of the faulty arithmetic — `width`, `height` and `charcount` come straight from the user-provided `struct console_font_op` — and the allocation-then-copy sequence is a single deterministic ioctl with no race to win, no memory grooming and no state the attacker cannot set up.\nPR:L - `vt_ioctl()` grants `perm` to any process whose controlling terminal is the VT, so an ordinary unprivileged user logged in on a virtual console (physical console, embedded/automotive/kiosk fbcon system, or a serial/VT login) can issue `KD_FONT_OP_SET` without any capability; only the alternative `CAP_SYS_TTY_CONFIG` route needs real root.\nUI:N - The attacker performs the ioctl on its own console session; no administrator or second user has to open a file, mount anything, or take any action.\nS:U - The undersized allocation and the overflowing copy both occur in kernel heap memory within the same security authority the attacker is already attacking; no VM, IOMMU, or sandbox boundary is crossed.\nC:H - A short kmalloc chunk followed by a length-mismatched copy loop corrupts adjacent slab objects, and the font is subsequently readable back via `KD_FONT_OP_GET`/`con_font_get()`, so out-of-bounds heap contents — kernel pointers, credentials, other slab users' data — can be disclosed to userspace.\nI:H - The overflow is an out-of-bounds heap write whose length and byte content are entirely attacker-chosen (the glyph bitmap), which is the classic primitive for overwriting neighbouring slab objects such as function pointers or `struct cred`, giving arbitrary modification and potential control-flow hijack.\nA:H - Writing past the end of the font allocation corrupts the slab and reliably produces a kernel oops, SLUB freelist BUG, or panic; the ioctl can be repeated at will, so it is a repeatable full-system denial of service." } ] } ], "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/fbcon.c" ], "versions": [ { "version": "96e41fc29e8af5c5085fb8a79cab8d0d00bab86c", "lessThan": "994bdc2d23c79087fbf7dcd9544454e8ebcef877", "status": "affected", "versionType": "git" }, { "version": "39b3cffb8cf3111738ea993e2757ab382253d86a", "lessThan": "9c8ec14075c5317edd6b242f1be8167aa1e4e333", "status": "affected", "versionType": "git" }, { "version": "39b3cffb8cf3111738ea993e2757ab382253d86a", "lessThan": "b8a6e85328aeb9881531dbe89bcd2637a06c3c95", "status": "affected", "versionType": "git" }, { "version": "39b3cffb8cf3111738ea993e2757ab382253d86a", "lessThan": "a6eb9f423b3db000aaedf83367b8539f6b72dcfc", "status": "affected", "versionType": "git" }, { "version": "39b3cffb8cf3111738ea993e2757ab382253d86a", "lessThan": "adac90bb1aaf45ca66f9db8ac100be16750ace78", "status": "affected", "versionType": "git" }, { "version": "39b3cffb8cf3111738ea993e2757ab382253d86a", "lessThan": "4a4bac869560f943edbe3c2b032062f6673b13d3", "status": "affected", "versionType": "git" }, { "version": "39b3cffb8cf3111738ea993e2757ab382253d86a", "lessThan": "c0c01f9aa08c8e10e10e8c9ebb5be01a4eff6eb7", "status": "affected", "versionType": "git" }, { "version": "39b3cffb8cf3111738ea993e2757ab382253d86a", "lessThan": "1a194e6c8e1ee745e914b0b7f50fa86c89ed13fe", "status": "affected", "versionType": "git" }, { "version": "ae021a904ac82d9fc81c25329d3c465c5a7d5686", "status": "affected", "versionType": "git" }, { "version": "451bffa366f2cc0e5314807cb847f31c0226efed", "status": "affected", "versionType": "git" }, { "version": "2c455e9c5865861f5ce09c5f596909495ed7657c", "status": "affected", "versionType": "git" }, { "version": "72f099805dbc907fbe8fa19bccdc31d3e2ee6e9e", "status": "affected", "versionType": "git" }, { "version": "34cf1aff169dc6dedad8d79da7bf1b4de2773dbc", "status": "affected", "versionType": "git" }, { "version": "5.4.62", "lessThan": "5.4.300", "status": "affected", "versionType": "semver" }, { "version": "4.4.235", "lessThan": "4.5", "status": "affected", "versionType": "semver" }, { "version": "4.9.235", "lessThan": "4.10", "status": "affected", "versionType": "semver" }, { "version": "4.14.196", "lessThan": "4.15", "status": "affected", "versionType": "semver" }, { "version": "4.19.143", "lessThan": "4.20", "status": "affected", "versionType": "semver" }, { "version": "5.8.6", "lessThan": "5.9", "status": "affected", "versionType": "semver" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "drivers/video/fbdev/core/fbcon.c" ], "versions": [ { "version": "5.9", "status": "affected" }, { "version": "0", "lessThan": "5.9", "status": "unaffected", "versionType": "semver" }, { "version": "5.4.300", "lessThanOrEqual": "5.4.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.10.245", "lessThanOrEqual": "5.10.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.15.194", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.155", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.109", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.50", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.16.10", "lessThanOrEqual": "6.16.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.17", "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": "5.4.62", "versionEndExcluding": "5.4.300" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.9", "versionEndExcluding": "5.10.245" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.9", "versionEndExcluding": "5.15.194" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.9", "versionEndExcluding": "6.1.155" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.9", "versionEndExcluding": "6.6.109" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.9", "versionEndExcluding": "6.12.50" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.9", "versionEndExcluding": "6.16.10" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.9", "versionEndExcluding": "6.17" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.4.235" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.9.235" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.14.196" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.19.143" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.8.6" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/994bdc2d23c79087fbf7dcd9544454e8ebcef877" }, { "url": "https://git.kernel.org/stable/c/9c8ec14075c5317edd6b242f1be8167aa1e4e333" }, { "url": "https://git.kernel.org/stable/c/b8a6e85328aeb9881531dbe89bcd2637a06c3c95" }, { "url": "https://git.kernel.org/stable/c/a6eb9f423b3db000aaedf83367b8539f6b72dcfc" }, { "url": "https://git.kernel.org/stable/c/adac90bb1aaf45ca66f9db8ac100be16750ace78" }, { "url": "https://git.kernel.org/stable/c/4a4bac869560f943edbe3c2b032062f6673b13d3" }, { "url": "https://git.kernel.org/stable/c/c0c01f9aa08c8e10e10e8c9ebb5be01a4eff6eb7" }, { "url": "https://git.kernel.org/stable/c/1a194e6c8e1ee745e914b0b7f50fa86c89ed13fe" } ], "title": "fbcon: fix integer overflow in fbcon_do_set_font", "x_generator": { "engine": "bippy-1.2.0" } }, "adp": [ { "metrics": [ { "other": { "type": "ssvc", "content": { "id": "CVE-2025-39967", "role": "CISA Coordinator", "options": [ { "Exploitation": "none" }, { "Automatable": "no" }, { "Technical Impact": "total" } ], "version": "2.0.3", "timestamp": "2026-06-10T20:42:14.769458Z" } } } ], "title": "CISA ADP Vulnrichment", "providerMetadata": { "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-06-11T18:44:20.970Z" } } ] } }