{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-63949","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","state":"PUBLISHED","assignerShortName":"Linux","dateReserved":"2026-07-19T07:54:57.023Z","datePublished":"2026-07-19T14:55:42.679Z","dateUpdated":"2026-07-19T14:55:42.679Z"},"containers":{"cna":{"providerMetadata":{"orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux","dateUpdated":"2026-07-19T14:55:42.679Z"},"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nauxdisplay: line-display: fix OOB read on zero-length message_store()\n\nlinedisp_display() unconditionally reads msg[count - 1] before\nchecking whether count is zero, so a write of zero bytes to the\nmessage sysfs attribute hits msg[-1]:\n\n\twrite(fd, \"\", 0);\n\n\t-> message_store(..., buf, count=0)\n\t   -> linedisp_display(linedisp, buf, count=0)\n\t      -> msg[count - 1] == '\\n'  ; OOB read\n\nThe kernfs write buffer for that store is a 1-byte allocation\n(kernfs_fop_write_iter() does kmalloc(len + 1) with len == 0),\nso msg[-1] is a 1-byte read before the slab object. On a\nKASAN-enabled kernel this trips an out-of-bounds report and\npanics; on stock kernels it silently reads adjacent slab data\nand, if that byte happens to be '\\n', the following count--\nwraps ssize_t 0 to -1 and is then passed to kmemdup_nul().\n\nlinedisp_display() is reached from the message_store() sysfs\ncallback (drivers/auxdisplay/line-display.c message attribute,\nmode 0644) and from the in-tree initial-message setup with\ncount == -1, so the OOB path is only userspace-triggerable via\nzero-byte writes; vfs_write() does not short-circuit on\ncount == 0 and kernfs_fop_write_iter() dispatches the store\ncallback regardless.\n\nGuard the trailing-newline trim with a count check. The\nexisting if (!count) block then takes the clear-display path\nunchanged.\n\nAffects every auxdisplay driver that registers via\nlinedisp_register() / linedisp_attach(): ht16k33, max6959,\nimg-ascii-lcd, seg-led-gpio."}],"affected":[{"product":"Linux","vendor":"Linux","defaultStatus":"unaffected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/auxdisplay/line-display.c"],"versions":[{"version":"7e76aece6f036cb7ada4858d6aa73825bfe22983","lessThan":"ca5b0781946d5083ceafa752141f47f085853620","status":"affected","versionType":"git"},{"version":"7e76aece6f036cb7ada4858d6aa73825bfe22983","lessThan":"8776032fe989a9b5fc77f2de5e03e4adb44c630e","status":"affected","versionType":"git"},{"version":"7e76aece6f036cb7ada4858d6aa73825bfe22983","lessThan":"3859960daeb9b7b39b9847b5b0113bc6081eb735","status":"affected","versionType":"git"},{"version":"7e76aece6f036cb7ada4858d6aa73825bfe22983","lessThan":"197476b126010bac1b3199833c6966cd6f54c2a9","status":"affected","versionType":"git"},{"version":"7e76aece6f036cb7ada4858d6aa73825bfe22983","lessThan":"6ad4f75ef9f3372fce8cad494e789ac6a5507bef","status":"affected","versionType":"git"},{"version":"7e76aece6f036cb7ada4858d6aa73825bfe22983","lessThan":"a7511dcd9dd4bc55d123f9b800c8a4ed2662e5c6","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/auxdisplay/line-display.c"],"versions":[{"version":"5.16","status":"affected"},{"version":"0","lessThan":"5.16","status":"unaffected","versionType":"semver"},{"version":"6.1.176","lessThanOrEqual":"6.1.*","status":"unaffected","versionType":"semver"},{"version":"6.6.143","lessThanOrEqual":"6.6.*","status":"unaffected","versionType":"semver"},{"version":"6.12.93","lessThanOrEqual":"6.12.*","status":"unaffected","versionType":"semver"},{"version":"6.18.35","lessThanOrEqual":"6.18.*","status":"unaffected","versionType":"semver"},{"version":"7.0.12","lessThanOrEqual":"7.0.*","status":"unaffected","versionType":"semver"},{"version":"7.1","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":"5.16","versionEndExcluding":"6.1.176"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.16","versionEndExcluding":"6.6.143"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.16","versionEndExcluding":"6.12.93"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.16","versionEndExcluding":"6.18.35"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.16","versionEndExcluding":"7.0.12"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.16","versionEndExcluding":"7.1"}]}]}],"references":[{"url":"https://git.kernel.org/stable/c/ca5b0781946d5083ceafa752141f47f085853620"},{"url":"https://git.kernel.org/stable/c/8776032fe989a9b5fc77f2de5e03e4adb44c630e"},{"url":"https://git.kernel.org/stable/c/3859960daeb9b7b39b9847b5b0113bc6081eb735"},{"url":"https://git.kernel.org/stable/c/197476b126010bac1b3199833c6966cd6f54c2a9"},{"url":"https://git.kernel.org/stable/c/6ad4f75ef9f3372fce8cad494e789ac6a5507bef"},{"url":"https://git.kernel.org/stable/c/a7511dcd9dd4bc55d123f9b800c8a4ed2662e5c6"}],"title":"auxdisplay: line-display: fix OOB read on zero-length message_store()","x_generator":{"engine":"bippy-1.2.0"}}}}