{"id":"CVE-2026-64082","state":"PUBLISHED","title":"riscv: Fix register corruption from uninitialized cregs on error","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nriscv: Fix register corruption from uninitialized cregs on error\n\ncompat_riscv_gpr_set() calls cregs_to_regs() unconditionally, even when\nuser_regset_copyin() fails. Since cregs is an uninitialized stack\nvariable, a copyin failure causes uninitialized stack data to be written\ninto the target task's pt_regs, corrupting its register state and\npotentially leaking kernel stack contents.\n\ncompat_restore_sigcontext() has the same issue: it calls cregs_to_regs()\neven when __copy_from_user() fails, leading to the same corruption of\nthe signal-returning task's register state on error.\n\nOnly call cregs_to_regs() when the user copy succeeds.","publishedAt":"2026-07-19T15:39:54.074Z","updatedAt":"2026-09-02T12:49:41.782Z","severity":{"score":7.8,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/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":"7383ee05314be58f8f9f018ee0ac53bef3808aea","status":"affected","lessThan":"f2d88b0d7aebfa4643fc58bbae57210c6daff9c6","versionType":"git"},{"version":"7383ee05314be58f8f9f018ee0ac53bef3808aea","status":"affected","lessThan":"66dedb6028c3df6c6a3372dd935b823917e150d5","versionType":"git"},{"version":"7383ee05314be58f8f9f018ee0ac53bef3808aea","status":"affected","lessThan":"2a7d1daf2674fe7d5b1cc99a4e3b5f0f72d5958f","versionType":"git"},{"version":"7383ee05314be58f8f9f018ee0ac53bef3808aea","status":"affected","lessThan":"0599aa23734c48de9bce36d043a9ec90c23945a1","versionType":"git"},{"version":"7383ee05314be58f8f9f018ee0ac53bef3808aea","status":"affected","lessThan":"9e020156833f1ad0d425a1e3d85b65639f1c1c50","versionType":"git"},{"version":"7383ee05314be58f8f9f018ee0ac53bef3808aea","status":"affected","lessThan":"6ebcbb53fc9bc30843054ed99fd60b8e542628f4","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["arch/riscv/kernel/compat_signal.c","arch/riscv/kernel/ptrace.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"5.19","status":"affected"},{"version":"0","status":"unaffected","lessThan":"5.19","versionType":"semver"},{"version":"6.1.187","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.156","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.108","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.49","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.0.11","status":"unaffected","lessThanOrEqual":"7.0.*","versionType":"semver"},{"version":"7.1","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["arch/riscv/kernel/compat_signal.c","arch/riscv/kernel/ptrace.c"]}],"references":["https://git.kernel.org/stable/c/f2d88b0d7aebfa4643fc58bbae57210c6daff9c6","https://git.kernel.org/stable/c/66dedb6028c3df6c6a3372dd935b823917e150d5","https://git.kernel.org/stable/c/2a7d1daf2674fe7d5b1cc99a4e3b5f0f72d5958f","https://git.kernel.org/stable/c/0599aa23734c48de9bce36d043a9ec90c23945a1","https://git.kernel.org/stable/c/9e020156833f1ad0d425a1e3d85b65639f1c1c50","https://git.kernel.org/stable/c/6ebcbb53fc9bc30843054ed99fd60b8e542628f4"],"weaknesses":[],"ingestedAt":"2026-10-29T20:12:41.951Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/64xxx/CVE-2026-64082.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-64082","state":"PUBLISHED","datePublished":"2026-07-19T15:39:54.074Z","dateUpdated":"2026-09-02T12:49:41.782Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-07-19T07:54:57.031Z"},"containers":{"cna":{"title":"riscv: Fix register corruption from uninitialized cregs on error","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nriscv: Fix register corruption from uninitialized cregs on error\n\ncompat_riscv_gpr_set() calls cregs_to_regs() unconditionally, even when\nuser_regset_copyin() fails. Since cregs is an uninitialized stack\nvariable, a copyin failure causes uninitialized stack data to be written\ninto the target task's pt_regs, corrupting its register state and\npotentially leaking kernel stack contents.\n\ncompat_restore_sigcontext() has the same issue: it calls cregs_to_regs()\neven when __copy_from_user() fails, leading to the same corruption of\nthe signal-returning task's register state on error.\n\nOnly call cregs_to_regs() when the user copy succeeds."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"7383ee05314be58f8f9f018ee0ac53bef3808aea","status":"affected","lessThan":"f2d88b0d7aebfa4643fc58bbae57210c6daff9c6","versionType":"git"},{"version":"7383ee05314be58f8f9f018ee0ac53bef3808aea","status":"affected","lessThan":"66dedb6028c3df6c6a3372dd935b823917e150d5","versionType":"git"},{"version":"7383ee05314be58f8f9f018ee0ac53bef3808aea","status":"affected","lessThan":"2a7d1daf2674fe7d5b1cc99a4e3b5f0f72d5958f","versionType":"git"},{"version":"7383ee05314be58f8f9f018ee0ac53bef3808aea","status":"affected","lessThan":"0599aa23734c48de9bce36d043a9ec90c23945a1","versionType":"git"},{"version":"7383ee05314be58f8f9f018ee0ac53bef3808aea","status":"affected","lessThan":"9e020156833f1ad0d425a1e3d85b65639f1c1c50","versionType":"git"},{"version":"7383ee05314be58f8f9f018ee0ac53bef3808aea","status":"affected","lessThan":"6ebcbb53fc9bc30843054ed99fd60b8e542628f4","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["arch/riscv/kernel/compat_signal.c","arch/riscv/kernel/ptrace.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"5.19","status":"affected"},{"version":"0","status":"unaffected","lessThan":"5.19","versionType":"semver"},{"version":"6.1.187","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.156","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.108","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.49","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.0.11","status":"unaffected","lessThanOrEqual":"7.0.*","versionType":"semver"},{"version":"7.1","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["arch/riscv/kernel/compat_signal.c","arch/riscv/kernel/ptrace.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/f2d88b0d7aebfa4643fc58bbae57210c6daff9c6"},{"url":"https://git.kernel.org/stable/c/66dedb6028c3df6c6a3372dd935b823917e150d5"},{"url":"https://git.kernel.org/stable/c/2a7d1daf2674fe7d5b1cc99a4e3b5f0f72d5958f"},{"url":"https://git.kernel.org/stable/c/0599aa23734c48de9bce36d043a9ec90c23945a1"},{"url":"https://git.kernel.org/stable/c/9e020156833f1ad0d425a1e3d85b65639f1c1c50"},{"url":"https://git.kernel.org/stable/c/6ebcbb53fc9bc30843054ed99fd60b8e542628f4"}],"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 bug is only reachable through local kernel interfaces—compat_rt_sigreturn and ptrace(PTRACE_SETREGSET)—with no network, adjacent-radio, or physical-device code path involved.\nAC:L - An attacker can reliably force the user copy to fail by racing munmap/mprotect against sigreturn or ptrace SETREGSET after access_ok, controlling both sides of the TOCTOU window.\nPR:L - The lowest-privilege path is compat_rt_sigreturn, callable by any unprivileged 32-bit compat process on a CONFIG_COMPAT RISC-V system without capabilities or root.\nUI:N - Exploitation requires no victim interaction; a local attacker corrupts their own task’s registers via rt_sigreturn or a tracee they already control as parent/tracer.\nS:U - Impact is confined to kernel register-state corruption and information disclosure within the same OS security boundary, not a VM escape or cross-authority sandbox breakout.\nC:H - On copy failure, uninitialized kernel stack data (up to the full compat_user_regs_struct) is written into pt_regs, leaking kernel memory contents into user-observable registers.\nI:H - The corruption overwrites all general-purpose registers in pt_regs—including program counter, stack pointer, and return address—constituting memory corruption exploitable for control-flow hijacking.\nA:H - Corrupted pt_regs reliably cause faults, SIGSEGV delivery, or erratic kernel/user execution, and the condition is repeatable for persistent denial of service."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-09-02T12:49:41.782Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.19","versionEndExcluding":"6.1.187"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.19","versionEndExcluding":"6.6.156"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.19","versionEndExcluding":"6.12.108"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.19","versionEndExcluding":"6.18.49"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.19","versionEndExcluding":"7.0.11"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.19","versionEndExcluding":"7.1"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}