CVE-2026-89882 (GCVE-0-2026-89882)
Vulnerability from cvelistv5
Published
2026-09-16 10:31
Modified
2026-10-19 08:54
Severity ?
7.8 (High) - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: media: rkvdec: hevc: guard INTER_REF_PIC_SET_PRED index underflow st_ref_pic_set_prediction() computes the reference RPS index as st_rps_idx - (delta_idx_minus1 + 1) per HEVC spec equation 7-59. Both operands are u8, so when delta_idx_minus1 + 1 exceeds the current index the subtraction wraps and the subsequent array access at calculated_rps_st_sets[ref_rps_idx] reads far out of bounds. A userspace V4L2 client that can open the RKVDEC m2m decoder can submit an EXT_SPS_ST_RPS control with INTER_REF_PIC_SET_PRED set and delta_idx_minus1 crafted to trigger the underflow. Reject the entry early when the reference index would underflow.
References
Impacted products
Vendor Product Version
Linux Linux Version: c9a59dc2acc72789d5c778af080d1e65af84862c
Version: c9a59dc2acc72789d5c778af080d1e65af84862c
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "drivers/media/platform/rockchip/rkvdec/rkvdec-hevc-common.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "74938f83a8abbee8f502dfb5d94213b2497d1edf",
              "status": "affected",
              "version": "c9a59dc2acc72789d5c778af080d1e65af84862c",
              "versionType": "git"
            },
            {
              "lessThan": "052c5ed5a1d96a6b24fd50ccda16fc6841ee7ca3",
              "status": "affected",
              "version": "c9a59dc2acc72789d5c778af080d1e65af84862c",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "drivers/media/platform/rockchip/rkvdec/rkvdec-hevc-common.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "7.0"
            },
            {
              "lessThan": "7.0",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.5",
              "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": "7.2.5",
                  "versionStartIncluding": "7.0",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.3",
                  "versionStartIncluding": "7.0",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nmedia: rkvdec: hevc: guard INTER_REF_PIC_SET_PRED index underflow\n\nst_ref_pic_set_prediction() computes the reference RPS index as\nst_rps_idx - (delta_idx_minus1 + 1) per HEVC spec equation 7-59.\nBoth operands are u8, so when delta_idx_minus1 + 1 exceeds the\ncurrent index the subtraction wraps and the subsequent array access\nat calculated_rps_st_sets[ref_rps_idx] reads far out of bounds.\n\nA userspace V4L2 client that can open the RKVDEC m2m decoder can\nsubmit an EXT_SPS_ST_RPS control with INTER_REF_PIC_SET_PRED set\nand delta_idx_minus1 crafted to trigger the underflow.\n\nReject the entry early when the reference index would underflow."
        }
      ],
      "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 - The EXT_SPS_ST_RPS control is applied only via VIDIOC_S_EXT_CTRLS or a media request on the local rkvdec V4L2 m2m node (/dev/videoN), then consumed in rkvdec_hevc_run after QBUF/STREAMON. The HEVC RPS parser is not reachable from the network stack.\nAC:L - The attacker sets INTER_REF_PIC_SET_PRED and a delta_idx_minus1 that makes the u8 index wrap (e.g. idx=0 and delta_idx_minus1=0 yields ref_rps_idx=255). v4l2-ctrls never validates delta_idx_minus1 and try_ctrl only checks SPS, so the out-of-bounds access is deterministic with no race.\nPR:L - rkvdec_open and the ioctl path perform no capability check. An unprivileged local account that can open the decoder node is sufficient, typically via the video group or the Android/embedded media codec service that sandboxed apps can reach.\nUI:N - The attacking process itself opens the decoder, attaches a crafted EXT_SPS_ST_RPS control, queues buffers, and starts streaming. No separate victim action is required.\nS:U - The underflow corrupts kernel heap, stack, and the driver\u0027s DMA RPS table inside the same kernel security authority. This is local privilege escalation, not a VM escape, IOMMU bypass, or sandbox-boundary crossing.\nC:H - A wrapped u8 ref_rps_idx indexes calculated_rps_st_sets tens of kilobytes past the kzalloc allocation (up to 255 * sizeof(struct calculated_rps_st_set)). Those out-of-bounds bytes become loop bounds and are copied into the hardware RPS table, giving an attacker-steerable kernel memory read.\nI:H - Out-of-bounds num_delta_pocs overflows the 16-byte stack arrays use_delta_flag and used_by_curr_pic_flag, later loops write past st_rps-\u003edelta_poc_s0[16] on the heap, and assemble_hw_st_rps bit-writes rps-\u003einfo with an unbounded index. That is an attacker-influenced kernel write usable for control-flow hijack.\nA:H - The far out-of-bounds pointer, stack smash, and DMA RPS-table overrun each cause a kernel oops, KASAN report, or wedged decoder, and the attacker can repeat the sequence at will."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-19T08:54:15.482Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/74938f83a8abbee8f502dfb5d94213b2497d1edf"
        },
        {
          "url": "https://git.kernel.org/stable/c/052c5ed5a1d96a6b24fd50ccda16fc6841ee7ca3"
        }
      ],
      "title": "media: rkvdec: hevc: guard INTER_REF_PIC_SET_PRED index underflow",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-89882",
    "datePublished": "2026-09-16T10:31:47.644Z",
    "dateReserved": "2026-09-11T19:38:34.772Z",
    "dateUpdated": "2026-10-19T08:54:15.482Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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