{"id":"CVE-2026-31447","state":"PUBLISHED","title":"ext4: reject mount if bigalloc with s_first_data_block != 0","description":"In the Linux kernel, the following vulnerability has been resolved:\n\next4: reject mount if bigalloc with s_first_data_block != 0\n\nbigalloc with s_first_data_block != 0 is not supported, reject mounting\nit.","publishedAt":"2026-04-22T13:53:43.467Z","updatedAt":"2026-10-19T18:35:48.523Z","severity":{"score":7.8,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H","source":"Linux"},"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"281b59959707dfae03ce038cdf231bf4904e170c","status":"affected","lessThan":"5ad6d994255e27a3254079dfb50ca861fc31f2d0","versionType":"git"},{"version":"281b59959707dfae03ce038cdf231bf4904e170c","status":"affected","lessThan":"3a926957cc95899ef88529710836edadc03c71a1","versionType":"git"},{"version":"281b59959707dfae03ce038cdf231bf4904e170c","status":"affected","lessThan":"7b58c110b4e1f028eb38eec9ed3555e9be81c8b0","versionType":"git"},{"version":"281b59959707dfae03ce038cdf231bf4904e170c","status":"affected","lessThan":"b77de3fceafbb39f30e4ff5dc986f863d5456417","versionType":"git"},{"version":"281b59959707dfae03ce038cdf231bf4904e170c","status":"affected","lessThan":"d787d3ae96648dc14a3b7ca8fde817177e82c1c7","versionType":"git"},{"version":"281b59959707dfae03ce038cdf231bf4904e170c","status":"affected","lessThan":"ad1f6d608f33f59d21a3d025615d6786a6443998","versionType":"git"},{"version":"281b59959707dfae03ce038cdf231bf4904e170c","status":"affected","lessThan":"7d5b04290156c3fc316eecc86a4f9d201ab7d44a","versionType":"git"},{"version":"281b59959707dfae03ce038cdf231bf4904e170c","status":"affected","lessThan":"3822743dc20386d9897e999dbb990befa3a5b3f8","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/ext4/super.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"3.2","status":"affected"},{"version":"0","status":"unaffected","lessThan":"3.2","versionType":"semver"},{"version":"5.10.253","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.203","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.168","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.131","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.80","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.21","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"6.19.11","status":"unaffected","lessThanOrEqual":"6.19.*","versionType":"semver"},{"version":"7.0","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/ext4/super.c"]}],"references":["https://git.kernel.org/stable/c/5ad6d994255e27a3254079dfb50ca861fc31f2d0","https://git.kernel.org/stable/c/3a926957cc95899ef88529710836edadc03c71a1","https://git.kernel.org/stable/c/7b58c110b4e1f028eb38eec9ed3555e9be81c8b0","https://git.kernel.org/stable/c/b77de3fceafbb39f30e4ff5dc986f863d5456417","https://git.kernel.org/stable/c/d787d3ae96648dc14a3b7ca8fde817177e82c1c7","https://git.kernel.org/stable/c/ad1f6d608f33f59d21a3d025615d6786a6443998","https://git.kernel.org/stable/c/7d5b04290156c3fc316eecc86a4f9d201ab7d44a","https://git.kernel.org/stable/c/3822743dc20386d9897e999dbb990befa3a5b3f8","https://cert-portal.siemens.com/productcert/html/ssa-082556.html","https://cert-portal.siemens.com/productcert/html/ssa-019113.html","https://cert-portal.siemens.com/productcert/html/ssa-457936.html"],"weaknesses":["CWE-20"],"ingestedAt":"2026-10-29T20:11:40.391Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/31xxx/CVE-2026-31447.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-31447","state":"PUBLISHED","datePublished":"2026-04-22T13:53:43.467Z","dateUpdated":"2026-10-19T18:35:48.523Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-03-09T15:48:24.091Z"},"containers":{"cna":{"title":"ext4: reject mount if bigalloc with s_first_data_block != 0","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\next4: reject mount if bigalloc with s_first_data_block != 0\n\nbigalloc with s_first_data_block != 0 is not supported, reject mounting\nit."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"281b59959707dfae03ce038cdf231bf4904e170c","status":"affected","lessThan":"5ad6d994255e27a3254079dfb50ca861fc31f2d0","versionType":"git"},{"version":"281b59959707dfae03ce038cdf231bf4904e170c","status":"affected","lessThan":"3a926957cc95899ef88529710836edadc03c71a1","versionType":"git"},{"version":"281b59959707dfae03ce038cdf231bf4904e170c","status":"affected","lessThan":"7b58c110b4e1f028eb38eec9ed3555e9be81c8b0","versionType":"git"},{"version":"281b59959707dfae03ce038cdf231bf4904e170c","status":"affected","lessThan":"b77de3fceafbb39f30e4ff5dc986f863d5456417","versionType":"git"},{"version":"281b59959707dfae03ce038cdf231bf4904e170c","status":"affected","lessThan":"d787d3ae96648dc14a3b7ca8fde817177e82c1c7","versionType":"git"},{"version":"281b59959707dfae03ce038cdf231bf4904e170c","status":"affected","lessThan":"ad1f6d608f33f59d21a3d025615d6786a6443998","versionType":"git"},{"version":"281b59959707dfae03ce038cdf231bf4904e170c","status":"affected","lessThan":"7d5b04290156c3fc316eecc86a4f9d201ab7d44a","versionType":"git"},{"version":"281b59959707dfae03ce038cdf231bf4904e170c","status":"affected","lessThan":"3822743dc20386d9897e999dbb990befa3a5b3f8","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/ext4/super.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"3.2","status":"affected"},{"version":"0","status":"unaffected","lessThan":"3.2","versionType":"semver"},{"version":"5.10.253","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.203","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.168","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.131","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.80","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.21","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"6.19.11","status":"unaffected","lessThanOrEqual":"6.19.*","versionType":"semver"},{"version":"7.0","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/ext4/super.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/5ad6d994255e27a3254079dfb50ca861fc31f2d0"},{"url":"https://git.kernel.org/stable/c/3a926957cc95899ef88529710836edadc03c71a1"},{"url":"https://git.kernel.org/stable/c/7b58c110b4e1f028eb38eec9ed3555e9be81c8b0"},{"url":"https://git.kernel.org/stable/c/b77de3fceafbb39f30e4ff5dc986f863d5456417"},{"url":"https://git.kernel.org/stable/c/d787d3ae96648dc14a3b7ca8fde817177e82c1c7"},{"url":"https://git.kernel.org/stable/c/ad1f6d608f33f59d21a3d025615d6786a6443998"},{"url":"https://git.kernel.org/stable/c/7d5b04290156c3fc316eecc86a4f9d201ab7d44a"},{"url":"https://git.kernel.org/stable/c/3822743dc20386d9897e999dbb990befa3a5b3f8"}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H","baseScore":7.8,"baseSeverity":"HIGH"},"scenarios":[{"lang":"en","value":"AV:L - The vulnerable ext4 code is reached through local filesystem mount and file-operation paths on an attacker-controlled ext4 image or block device, not through a network protocol.\nAC:L - The attacker controls the filesystem geometry and extent layout, and the reported trigger is deterministic after mounting and operating on the crafted filesystem; no race or external timing condition is required.\nPR:N - Direct mounting is gated by CAP_SYS_ADMIN in the initial user namespace because ext4 lacks FS_USERNS_MOUNT, but in the attacker-supplied filesystem scenario the privileged mount is performed by the victim or system automounter. The attacker does not need their own kernel privileges.\nUI:R - Exploitation requires a victim or privileged mounting path to mount the crafted ext4 filesystem and perform an operation such as unlink/truncate on it.\nS:U - The impact remains within the kernel/filesystem security authority; this is not a VM escape, IOMMU bypass, or cross-scope boundary violation.\nC:H - The bug is a use-after-free in ext4 extent metadata handling, and UAF conditions can expose reused memory contents or be shaped into broader kernel information disclosure.\nI:H - The faulty cluster arithmetic can free and reuse metadata blocks still referenced by extents, creating memory/filesystem metadata corruption that is defensibly exploitable for high-integrity impact.\nA:H - The observed failure is a KASAN use-after-free in ext4_ext_remove_space and can crash or destabilize the kernel, giving high availability impact."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-08-05T12:22:37.767Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.2","versionEndExcluding":"5.10.253"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.2","versionEndExcluding":"5.15.203"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.2","versionEndExcluding":"6.1.168"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.2","versionEndExcluding":"6.6.131"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.2","versionEndExcluding":"6.12.80"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.2","versionEndExcluding":"6.18.21"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.2","versionEndExcluding":"6.19.11"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.2","versionEndExcluding":"7.0"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}},"adp":[{"affected":[{"vendor":"Siemens","product":"SIMATIC S7-1500 CPU 1518-4 PN/DP MFP","defaultStatus":"unknown","versions":[{"version":"V3.1.6","status":"affected","lessThan":"*","versionType":"custom"}]},{"vendor":"Siemens","product":"SIMATIC S7-1500 CPU 1518-4 PN/DP MFP","defaultStatus":"unknown","versions":[{"version":"V3.1.5","status":"affected","lessThan":"*","versionType":"custom"}]},{"vendor":"Siemens","product":"SIMATIC S7-1500 CPU 1518-4 PN/DP MFP","defaultStatus":"unknown","versions":[{"version":"V3.1.7","status":"affected","lessThan":"*","versionType":"custom"}]},{"vendor":"Siemens","product":"SIMATIC S7-1500 CPU 1518-4 PN/DP MFP","defaultStatus":"unknown","versions":[{"version":"V3.1.6","status":"affected","lessThan":"*","versionType":"custom"}]},{"vendor":"Siemens","product":"SIMATIC S7-1500 CPU 1518-4 PN/DP MFP","defaultStatus":"unknown","versions":[{"version":"V3.1.5","status":"affected","lessThan":"*","versionType":"custom"}]},{"vendor":"Siemens","product":"SIMATIC S7-1500 CPU 1518-4 PN/DP MFP","defaultStatus":"unknown","versions":[{"version":"V3.1.7","status":"affected","lessThan":"*","versionType":"custom"}]},{"vendor":"Siemens","product":"SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP","defaultStatus":"unknown","versions":[{"version":"V3.1.6","status":"affected","lessThan":"*","versionType":"custom"}]},{"vendor":"Siemens","product":"SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP","defaultStatus":"unknown","versions":[{"version":"V3.1.5","status":"affected","lessThan":"*","versionType":"custom"}]},{"vendor":"Siemens","product":"SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP","defaultStatus":"unknown","versions":[{"version":"V3.1.7","status":"affected","lessThan":"*","versionType":"custom"}]},{"vendor":"Siemens","product":"SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP","defaultStatus":"unknown","versions":[{"version":"V3.1.6","status":"affected","lessThan":"*","versionType":"custom"}]},{"vendor":"Siemens","product":"SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP","defaultStatus":"unknown","versions":[{"version":"V3.1.5","status":"affected","lessThan":"*","versionType":"custom"}]},{"vendor":"Siemens","product":"SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP","defaultStatus":"unknown","versions":[{"version":"V3.1.7","status":"affected","lessThan":"*","versionType":"custom"}]},{"vendor":"Siemens","product":"SIPLUS S7-1500 CPU 1518-4 PN/DP MFP","defaultStatus":"unknown","versions":[{"version":"V3.1.6","status":"affected","lessThan":"*","versionType":"custom"}]},{"vendor":"Siemens","product":"SIPLUS S7-1500 CPU 1518-4 PN/DP MFP","defaultStatus":"unknown","versions":[{"version":"V3.1.5","status":"affected","lessThan":"*","versionType":"custom"}]},{"vendor":"Siemens","product":"SIPLUS S7-1500 CPU 1518-4 PN/DP MFP","defaultStatus":"unknown","versions":[{"version":"V3.1.7","status":"affected","lessThan":"*","versionType":"custom"}]}],"references":[{"url":"https://cert-portal.siemens.com/productcert/html/ssa-082556.html"},{"url":"https://cert-portal.siemens.com/productcert/html/ssa-019113.html"},{"url":"https://cert-portal.siemens.com/productcert/html/ssa-457936.html"}],"providerMetadata":{"shortName":"siemens-SADP","orgId":"0b142b55-0307-4c5a-b3c9-f314f3fb7c5e","dateUpdated":"2026-10-15T01:16:18.474Z"},"x_adpType":"supplier"},{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"id":"CVE-2026-31447","role":"CISA Coordinator","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"total"}],"version":"2.0.3","timestamp":"2026-10-16T15:09:23.320699Z"}}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-20","lang":"en","type":"CWE","description":"CWE-20 Improper Input Validation"}]}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-10-19T18:35:48.523Z"}}]}}}