{"id":"CVE-2026-43378","state":"PUBLISHED","title":"smb: server: fix use-after-free in smb2_open()","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nsmb: server: fix use-after-free in smb2_open()\n\nThe opinfo pointer obtained via rcu_dereference(fp->f_opinfo) is\ndereferenced after rcu_read_unlock(), creating a use-after-free\nwindow.","publishedAt":"2026-05-08T14:21:27.319Z","updatedAt":"2026-08-05T12:27:38.612Z","severity":{"score":9.8,"label":"Critical","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","source":"Linux"},"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9","status":"affected","lessThan":"e1b21e6066615e7d3d3a7aa2677e415e563fd7cc","versionType":"git"},{"version":"e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9","status":"affected","lessThan":"b720c84087cb547f23ce03eab93568c1769e4556","versionType":"git"},{"version":"e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9","status":"affected","lessThan":"54b48ae83de8bb06e65079d96368efe359d4909c","versionType":"git"},{"version":"e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9","status":"affected","lessThan":"8f5b1a7cb009a93c48e9e334a2f59a660f9afc07","versionType":"git"},{"version":"e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9","status":"affected","lessThan":"190e5f808e8058640b408ccfed25440b441a718a","versionType":"git"},{"version":"e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9","status":"affected","lessThan":"1e689a56173827669a35da7cb2a3c78ed5c53680","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/smb/server/smb2pdu.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"5.15","status":"affected"},{"version":"0","status":"unaffected","lessThan":"5.15","versionType":"semver"},{"version":"6.1.167","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.130","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.78","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.19","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"6.19.9","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/smb/server/smb2pdu.c"]}],"references":["https://git.kernel.org/stable/c/e1b21e6066615e7d3d3a7aa2677e415e563fd7cc","https://git.kernel.org/stable/c/b720c84087cb547f23ce03eab93568c1769e4556","https://git.kernel.org/stable/c/54b48ae83de8bb06e65079d96368efe359d4909c","https://git.kernel.org/stable/c/8f5b1a7cb009a93c48e9e334a2f59a660f9afc07","https://git.kernel.org/stable/c/190e5f808e8058640b408ccfed25440b441a718a","https://git.kernel.org/stable/c/1e689a56173827669a35da7cb2a3c78ed5c53680"],"weaknesses":[],"ingestedAt":"2026-10-29T20:11:57.932Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/43xxx/CVE-2026-43378.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-43378","state":"PUBLISHED","datePublished":"2026-05-08T14:21:27.319Z","dateUpdated":"2026-08-05T12:27:38.612Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-05-01T14:12:56.006Z"},"containers":{"cna":{"title":"smb: server: fix use-after-free in smb2_open()","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nsmb: server: fix use-after-free in smb2_open()\n\nThe opinfo pointer obtained via rcu_dereference(fp->f_opinfo) is\ndereferenced after rcu_read_unlock(), creating a use-after-free\nwindow."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9","status":"affected","lessThan":"e1b21e6066615e7d3d3a7aa2677e415e563fd7cc","versionType":"git"},{"version":"e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9","status":"affected","lessThan":"b720c84087cb547f23ce03eab93568c1769e4556","versionType":"git"},{"version":"e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9","status":"affected","lessThan":"54b48ae83de8bb06e65079d96368efe359d4909c","versionType":"git"},{"version":"e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9","status":"affected","lessThan":"8f5b1a7cb009a93c48e9e334a2f59a660f9afc07","versionType":"git"},{"version":"e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9","status":"affected","lessThan":"190e5f808e8058640b408ccfed25440b441a718a","versionType":"git"},{"version":"e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9","status":"affected","lessThan":"1e689a56173827669a35da7cb2a3c78ed5c53680","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/smb/server/smb2pdu.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"5.15","status":"affected"},{"version":"0","status":"unaffected","lessThan":"5.15","versionType":"semver"},{"version":"6.1.167","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.130","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.78","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.19","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"6.19.9","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/smb/server/smb2pdu.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/e1b21e6066615e7d3d3a7aa2677e415e563fd7cc"},{"url":"https://git.kernel.org/stable/c/b720c84087cb547f23ce03eab93568c1769e4556"},{"url":"https://git.kernel.org/stable/c/54b48ae83de8bb06e65079d96368efe359d4909c"},{"url":"https://git.kernel.org/stable/c/8f5b1a7cb009a93c48e9e334a2f59a660f9afc07"},{"url":"https://git.kernel.org/stable/c/190e5f808e8058640b408ccfed25440b441a718a"},{"url":"https://git.kernel.org/stable/c/1e689a56173827669a35da7cb2a3c78ed5c53680"}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","baseScore":9.8,"baseSeverity":"CRITICAL"},"scenarios":[{"lang":"en","value":"AV:N - The vulnerable path is ksmbd's SMB2 CREATE handler, reachable over the SMB server network listener on TCP/445 or SMB Direct. A remote client can drive the request path to `smb2_open()`.\nAC:L - The bug is a UAF window around concurrent oplock/lease state changes, and an attacker can create concurrent SMB opens/lease breaks using multiple requests or connections. Under the rule to choose higher severity when uncertain, this is Low complexity.\nPR:N - `SMB2_CREATE` requires a valid session and tree connection, but ksmbd supports guest/anonymous SMB sessions and guest shares in a reasonable deployment. In that scenario no prior credentials are required.\nUI:N - Exploitation is driven entirely by network SMB requests. No victim user action is required after the server is running.\nS:U - The vulnerability is in the kernel SMB server and impacts the same host kernel security authority. It does not inherently cross a VM, hypervisor, or separate security scope boundary.\nC:H - The flaw is a use-after-free of `struct oplock_info` and its lease data after RCU protection is dropped. Kernel UAF memory corruption can be leveraged for high-impact information disclosure.\nI:H - The dangling `oplock_info` pointer can be used after free while building the SMB2 CREATE response, creating exploitable kernel memory corruption. UAFs are treated as capable of arbitrary write or control-flow impact.\nA:H - A remotely triggerable kernel UAF can cause an oops, panic, or service crash. Repeated SMB requests can make the availability impact high."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-08-05T12:27:38.612Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.15","versionEndExcluding":"6.1.167"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.15","versionEndExcluding":"6.6.130"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.15","versionEndExcluding":"6.12.78"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.15","versionEndExcluding":"6.18.19"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.15","versionEndExcluding":"6.19.9"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.15","versionEndExcluding":"7.0"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}