{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "arch/riscv/include/asm/futex.h"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "2e5c80bbc062a8dda33e687ebf7be8f074ee4f7d",
              "status": "affected",
              "version": "2e1743085887ba3f553c2bb472a75a3ff744b242",
              "versionType": "git"
            },
            {
              "lessThan": "8e48d8d51ab37b7decfbff3e2844e027a52ad6ea",
              "status": "affected",
              "version": "2e1743085887ba3f553c2bb472a75a3ff744b242",
              "versionType": "git"
            },
            {
              "lessThan": "405290be962b32eec842776fbe3bdf81f15b1676",
              "status": "affected",
              "version": "2e1743085887ba3f553c2bb472a75a3ff744b242",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "arch/riscv/include/asm/futex.h"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.13"
            },
            {
              "lessThan": "6.13",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.57",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.11",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.57",
                  "versionStartIncluding": "6.13",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.2.11",
                  "versionStartIncluding": "6.13",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.3",
                  "versionStartIncluding": "6.13",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nriscv: futex: untag the user pointer before the atomic access\n\naccess_ok() checks untagged_addr(uaddr), but arch_futex_atomic_op_inuser()\nand futex_atomic_cmpxchg_inatomic() hand the raw uaddr to the inline asm\namoswap/amoadd/.../lr.w+sc.w through the \"+m\" (*uaddr) operand.  When the\ntagged address ABI is enabled (CONFIG_RISCV_ISA_SUPM, prctl\nPR_SET_TAGGED_ADDR_CTRL with PMLEN != 0), those two addresses differ: a\nuser pointer whose top PMLEN bits hold a tag passes access_ok() after\nuntagging, but the atomic is then performed on the still-tagged raw\naddress.\n\nSupervisor-mode data accesses are not subject to the U-mode pointer\nmasking (that is governed by menvcfg.PMM, which the kernel does not set),\nso hardware does not strip the tag for the kernel\u0027s own access.  With\nSv57 and PMLEN=16 the tag bits overlap the canonical-address bits, so a\ntagged pointer can name a canonical kernel virtual address (e.g. in the\nlinear map) whose untagged form is a valid user address.  An unprivileged\nprocess can thus make FUTEX_WAKE_OP perform an atomic read-modify-write on\nan arbitrary kernel address, with the matching FUTEX_OP_CMP_* result\nserving as a read oracle.\n\nget_user()/put_user()/raw_copy_{to,from}_user() already untag the pointer\nafter the access_ok() check; do the same in the futex helpers so the\natomic operates on the address that was actually validated."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 7.8,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:L - `sys_futex(FUTEX_WAKE_OP_PRIVATE)` follows `do_futex()` \u2192 `futex_wake_op()` \u2192 `futex_atomic_op_inuser()` \u2192 the patched `arch_futex_atomic_op_inuser()` using attacker-supplied `uaddr2`; no network data reaches this local syscall path.\nAC:L - On an affected Sv57 system supporting PMLEN=16, the attacker deterministically enables tagged addresses with `prctl()` and supplies a canonical linear-map pointer; no race, victim state, or second actor is required.\nPR:L - `sys_prctl(PR_SET_TAGGED_ADDR_CTRL)` and `sys_futex()` contain no capability or credential checks, so an ordinary unprivileged process can enable PMLEN=16 and invoke `FUTEX_WAKE_OP_PRIVATE`.\nUI:N - The attacking process performs both `prctl()` setup and the futex operations itself; no victim must open, mount, approve, or otherwise act.\nS:U - The AMO instructions corrupt the host kernel\u0027s own linear-map memory, producing ordinary local kernel privilege escalation without crossing a VM, IOMMU, or separate security authority.\nC:H - The raw-address AMO returns the prior 32-bit kernel value to `futex_atomic_op_inuser()`, whose `FUTEX_OP_CMP_*` result can be observed through controlled waiters, providing a repeatable read oracle over direct-mapped physical memory.\nI:H - `arch_futex_atomic_op_inuser()` executes `amoswap`, `amoadd`, `amoor`, `amoand`, or `amoxor` at the chosen kernel address; SET followed by shifted OR operations permits controlled 32-bit kernel-memory writes and privilege escalation.\nA:H - The same chosen-address AMOs can overwrite direct-mapped kernel objects, credentials, or page-table memory; corrupting such live kernel state can reliably cause an oops, panic, or complete system failure."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-24T14:10:03.722Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/2e5c80bbc062a8dda33e687ebf7be8f074ee4f7d"
        },
        {
          "url": "https://git.kernel.org/stable/c/8e48d8d51ab37b7decfbff3e2844e027a52ad6ea"
        },
        {
          "url": "https://git.kernel.org/stable/c/405290be962b32eec842776fbe3bdf81f15b1676"
        }
      ],
      "title": "riscv: futex: untag the user pointer before the atomic access",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-99016",
    "datePublished": "2026-10-23T12:20:47.859Z",
    "dateReserved": "2026-09-25T10:25:14.386Z",
    "dateUpdated": "2026-10-24T14:10:03.722Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}