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CVE-2026-89718 (GCVE-0-2026-89718)

Vulnerability from cvelistv5 – Published: 2026-09-11 19:46 – Updated: 2026-09-11 19:46
VLAI
Title
zram: fix out-of-bounds access in writeback_store()
Summary
In the Linux kernel, the following vulnerability has been resolved: zram: fix out-of-bounds access in writeback_store() Patch series "zram: fix stale scan bounds after reinitialization". Both writeback_store() and read_block_state() derive their table scan bounds from zram->disksize before acquiring dev_lock. If the device is reset and reinitialized with a smaller disksize between that read and lock acquisition, the bound can describe the old table while the scan operates on the new one. This can lead to out-of-bounds slot accesses. Move both bound calculations under dev_lock so each bound remains consistent with the table throughout its scan. Keep the fixes separate because the affected interfaces originate from different commits and can be backported independently. This patch (of 2): writeback_store() calculates the table scan bounds before taking dev_lock. A reset followed by reconfiguration with a smaller disksize can therefore replace zram->table while writeback_store() is waiting for the lock. Once it acquires the lock, it sees an initialized device but scans the new table using the old upper bound, resulting in an out-of-bounds access. Calculate the number of pages while holding dev_lock so the scan bound matches the table protected by the lock.
Severity
No CVSS data available.
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: a939888ec38bf1f33e4a903056677e92a4844244 , < 07a82a66f8c1894d92e51d97542c32ebf2c51b09 (git)
Affected: a939888ec38bf1f33e4a903056677e92a4844244 , < 894913e2d35c46ff19a77530907771ae57862b96 (git)
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Linux Linux Affected: 5.0
Unaffected: 0 , < 5.0 (semver)
Unaffected: 7.2.4 , ≤ 7.2.* (semver)
Unaffected: 7.3-rc1 , ≤ * (original_commit_for_fix)
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{
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          "product": "Linux",
          "programFiles": [
            "drivers/block/zram/zram_drv.c"
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            }
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      "cpeApplicability": [
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                  "vulnerable": true
                },
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              "operator": "OR"
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      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nzram: fix out-of-bounds access in writeback_store()\n\nPatch series \"zram: fix stale scan bounds after reinitialization\".\n\nBoth writeback_store() and read_block_state() derive their table scan\nbounds from zram-\u003edisksize before acquiring dev_lock.  If the device is\nreset and reinitialized with a smaller disksize between that read and lock\nacquisition, the bound can describe the old table while the scan operates\non the new one.  This can lead to out-of-bounds slot accesses.\n\nMove both bound calculations under dev_lock so each bound remains\nconsistent with the table throughout its scan.  Keep the fixes separate\nbecause the affected interfaces originate from different commits and can\nbe backported independently.\n\n\nThis patch (of 2):\n\nwriteback_store() calculates the table scan bounds before taking dev_lock.\nA reset followed by reconfiguration with a smaller disksize can therefore\nreplace zram-\u003etable while writeback_store() is waiting for the lock.  Once\nit acquires the lock, it sees an initialized device but scans the new\ntable using the old upper bound, resulting in an out-of-bounds access.\n\nCalculate the number of pages while holding dev_lock so the scan bound\nmatches the table protected by the lock."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-09-11T19:46:31.443Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/07a82a66f8c1894d92e51d97542c32ebf2c51b09"
        },
        {
          "url": "https://git.kernel.org/stable/c/894913e2d35c46ff19a77530907771ae57862b96"
        }
      ],
      "title": "zram: fix out-of-bounds access in writeback_store()",
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  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-89718",
    "datePublished": "2026-09-11T19:46:31.443Z",
    "dateReserved": "2026-09-11T19:38:34.752Z",
    "dateUpdated": "2026-09-11T19:46:31.443Z",
    "state": "PUBLISHED"
  },
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  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
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      "date": "2026-09-15",
      "epss": "0.00155",
      "percentile": "0.05021"
    },
    "nvd": "{\"cve\":{\"id\":\"CVE-2026-89718\",\"sourceIdentifier\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"published\":\"2026-09-11T20:19:59.377\",\"lastModified\":\"2026-09-11T20:19:59.377\",\"vulnStatus\":\"Received\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"In the Linux kernel, the following vulnerability has been resolved:\\n\\nzram: fix out-of-bounds access in writeback_store()\\n\\nPatch series \\\"zram: fix stale scan bounds after reinitialization\\\".\\n\\nBoth writeback_store() and read_block_state() derive their table scan\\nbounds from zram-\u003edisksize before acquiring dev_lock.  If the device is\\nreset and reinitialized with a smaller disksize between that read and lock\\nacquisition, the bound can describe the old table while the scan operates\\non the new one.  This can lead to out-of-bounds slot accesses.\\n\\nMove both bound calculations under dev_lock so each bound remains\\nconsistent with the table throughout its scan.  Keep the fixes separate\\nbecause the affected interfaces originate from different commits and can\\nbe backported independently.\\n\\n\\nThis patch (of 2):\\n\\nwriteback_store() calculates the table scan bounds before taking dev_lock.\\nA reset followed by reconfiguration with a smaller disksize can therefore\\nreplace zram-\u003etable while writeback_store() is waiting for the lock.  Once\\nit acquires the lock, it sees an initialized device but scans the new\\ntable using the old upper bound, resulting in an out-of-bounds access.\\n\\nCalculate the number of pages while holding dev_lock so the scan bound\\nmatches the table protected by the lock.\"}],\"affected\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"affectedData\":[{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"unaffected\",\"programFiles\":[\"drivers/block/zram/zram_drv.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"a939888ec38bf1f33e4a903056677e92a4844244\",\"lessThan\":\"07a82a66f8c1894d92e51d97542c32ebf2c51b09\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"a939888ec38bf1f33e4a903056677e92a4844244\",\"lessThan\":\"894913e2d35c46ff19a77530907771ae57862b96\",\"versionType\":\"git\",\"status\":\"affected\"}]},{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"affected\",\"programFiles\":[\"drivers/block/zram/zram_drv.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"5.0\",\"status\":\"affected\"},{\"version\":\"0\",\"lessThan\":\"5.0\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"7.2.4\",\"lessThanOrEqual\":\"7.2.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"7.3-rc1\",\"lessThanOrEqual\":\"*\",\"versionType\":\"original_commit_for_fix\",\"status\":\"unaffected\"}]}]}],\"metrics\":{},\"references\":[{\"url\":\"https://git.kernel.org/stable/c/07a82a66f8c1894d92e51d97542c32ebf2c51b09\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/894913e2d35c46ff19a77530907771ae57862b96\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"}]}}",
    "redhat_vex": {
      "aggregate_severity": "Moderate",
      "current_release_date": "2026-09-15T05:37:06+00:00",
      "cve": "CVE-2026-89718",
      "id": "CVE-2026-89718",
      "initial_release_date": "2026-09-11T19:46:31.443000+00:00",
      "product_status:known_affected": "2",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: Linux kernel: zram out-of-bounds access can lead to system instability",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89718.json",
      "version": "3"
    }
  }
}



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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

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  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
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