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CVE-2026-93203 (GCVE-0-2026-93203)

Vulnerability from cvelistv5 – Published: 2026-09-17 16:12 – Updated: 2026-09-17 16:12
VLAI
Title
batman-adv: bla: avoid CRC corruption due to parallel claim add
Summary
In the Linux kernel, the following vulnerability has been resolved: batman-adv: bla: avoid CRC corruption due to parallel claim add batadv_bla_add_claim() is used to add claims and modify the backbone of claims for CLAIM frames from remote backbones and local packets. When it handles a claim, it needs to either * add the new claim's CRC to the backbone CRC * remove the already existing claim's CRC from the old backbone and add it to the new backbone But when the "new" claim code was running in parallel to the "change backbone" code, it can happen that the CRC was invalid because the backbone_gw of the claim was changed twice in the "new" claim code path: * CPU0 creates the claim for gateway A and publishes it in the claim hash. The crc16 of the address has not yet been added to A's crc at this point. * CPU1 processes a claim frame of gateway B for the same client, finds the just published claim, and performs the ownership change: it switches the pointer to B, removes the crc16 from A's crc - which never contained it - and adds it to B's crc. * CPU0 continues behind the creation branch, unconditionally switches the pointer back to A without compensating B's crc (its remove_crc is false for the creation path), and finally adds the crc16 to A's crc The CRC is then wrong for both: * claim belongs to A: but CRC is not part of backbone A's CRC * claim doesn't belong to B: CRC is still part of backbone B's CRC This wrong CRC is never recomputated from the stored claims. For local backbone claims, this can also not recovered using syncs. To avoid this, split the functionality in clear separate parts: * new claim which always adds claim CRC to the backbone CRC (but never changes the already set backbone_gw of the claim back) * update of existing claim which automatically changes the backbone_gw entry and only updates both backbone CRCs when there was an actual change
Severity
No CVSS data available.
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 23721387c409087fd3b97e274f34d3ddc0970b74 , < 3d4a9ae2c69c0fe4c3c69587288241243bb7a39b (git)
Affected: 23721387c409087fd3b97e274f34d3ddc0970b74 , < ad982d925f00d860d2467811256ffadcccd9e4a7 (git)
Affected: 23721387c409087fd3b97e274f34d3ddc0970b74 , < d5b0e7574da5a485f4dbec32a15911900a4487c2 (git)
Affected: 23721387c409087fd3b97e274f34d3ddc0970b74 , < a3e07db74f22a85aeeb51c600da5c98b9cbca11f (git)
Affected: 23721387c409087fd3b97e274f34d3ddc0970b74 , < 1d390db003cbb52cdd86837608bff3794501a5ea (git)
Affected: 23721387c409087fd3b97e274f34d3ddc0970b74 , < 8bcfa58c4277bff1882a23547c37ab08aa1de12f (git)
Affected: 23721387c409087fd3b97e274f34d3ddc0970b74 , < e54602d9e38db8573f2097d60c7ea8be0a5af1fa (git)
Affected: 23721387c409087fd3b97e274f34d3ddc0970b74 , < 08645ab95768b88e2ff85a89211994651710465b (git)
guessed Create a notification for this product.
Linux Linux Affected: 3.5
Unaffected: 0 , < 3.5 (semver)
Unaffected: 5.10.270 , ≤ 5.10.* (semver)
Unaffected: 5.15.221 , ≤ 5.15.* (semver)
Unaffected: 6.1.188 , ≤ 6.1.* (semver)
Unaffected: 6.6.157 , ≤ 6.6.* (semver)
Unaffected: 6.12.110 , ≤ 6.12.* (semver)
Unaffected: 6.18.52 , ≤ 6.18.* (semver)
Unaffected: 7.2.6 , ≤ 7.2.* (semver)
Unaffected: 7.3-rc1 , ≤ * (original_commit_for_fix)
guessed Create a notification for this product.
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              "negate": false,
              "operator": "OR"
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      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbatman-adv: bla: avoid CRC corruption due to parallel claim add\n\nbatadv_bla_add_claim() is used to add claims and modify the backbone of\nclaims for CLAIM frames from remote backbones and local packets. When it\nhandles a claim, it needs to either\n\n* add the new claim\u0027s CRC to the backbone CRC\n* remove the already existing claim\u0027s CRC from the old backbone and add it\n  to the new backbone\n\nBut when the \"new\" claim code was running in parallel to the \"change\nbackbone\" code, it can happen that the CRC was invalid because the\nbackbone_gw of the claim was changed twice in the \"new\" claim code path:\n\n* CPU0 creates the claim for gateway A and publishes it in the claim\n  hash. The crc16 of the address has not yet been added to A\u0027s crc at\n  this point.\n\n* CPU1 processes a claim frame of gateway B for the same client, finds\n  the just published claim, and performs the ownership change: it\n  switches the pointer to B, removes the crc16 from A\u0027s crc - which\n  never contained it - and adds it to B\u0027s crc.\n\n* CPU0 continues behind the creation branch, unconditionally switches\n  the pointer back to A without compensating B\u0027s crc (its remove_crc\n  is false for the creation path), and finally adds the crc16 to A\u0027s\n  crc\n\nThe CRC is then wrong for both:\n\n* claim belongs to A: but CRC is not part of backbone A\u0027s CRC\n* claim doesn\u0027t belong to B: CRC is still part of backbone B\u0027s CRC\n\nThis wrong CRC is never recomputated from the stored claims. For local\nbackbone claims, this can also not recovered using syncs.\n\nTo avoid this, split the functionality in clear separate parts:\n\n* new claim which always adds claim CRC to the backbone CRC (but never\n  changes the already set backbone_gw of the claim back)\n\n* update of existing claim which automatically changes the backbone_gw\n  entry and only updates both backbone CRCs when there was an actual change"
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-09-17T16:12:23.742Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
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          "url": "https://git.kernel.org/stable/c/3d4a9ae2c69c0fe4c3c69587288241243bb7a39b"
        },
        {
          "url": "https://git.kernel.org/stable/c/ad982d925f00d860d2467811256ffadcccd9e4a7"
        },
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          "url": "https://git.kernel.org/stable/c/d5b0e7574da5a485f4dbec32a15911900a4487c2"
        },
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          "url": "https://git.kernel.org/stable/c/a3e07db74f22a85aeeb51c600da5c98b9cbca11f"
        },
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          "url": "https://git.kernel.org/stable/c/1d390db003cbb52cdd86837608bff3794501a5ea"
        },
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          "url": "https://git.kernel.org/stable/c/8bcfa58c4277bff1882a23547c37ab08aa1de12f"
        },
        {
          "url": "https://git.kernel.org/stable/c/e54602d9e38db8573f2097d60c7ea8be0a5af1fa"
        },
        {
          "url": "https://git.kernel.org/stable/c/08645ab95768b88e2ff85a89211994651710465b"
        }
      ],
      "title": "batman-adv: bla: avoid CRC corruption due to parallel claim add",
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-93203",
    "datePublished": "2026-09-17T16:12:23.742Z",
    "dateReserved": "2026-09-17T16:02:15.092Z",
    "dateUpdated": "2026-09-17T16:12:23.742Z",
    "state": "PUBLISHED"
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When it\\nhandles a claim, it needs to either\\n\\n* add the new claim\u0027s CRC to the backbone CRC\\n* remove the already existing claim\u0027s CRC from the old backbone and add it\\n  to the new backbone\\n\\nBut when the \\\"new\\\" claim code was running in parallel to the \\\"change\\nbackbone\\\" code, it can happen that the CRC was invalid because the\\nbackbone_gw of the claim was changed twice in the \\\"new\\\" claim code path:\\n\\n* CPU0 creates the claim for gateway A and publishes it in the claim\\n  hash. The crc16 of the address has not yet been added to A\u0027s crc at\\n  this point.\\n\\n* CPU1 processes a claim frame of gateway B for the same client, finds\\n  the just published claim, and performs the ownership change: it\\n  switches the pointer to B, removes the crc16 from A\u0027s crc - which\\n  never contained it - and adds it to B\u0027s crc.\\n\\n* CPU0 continues behind the creation branch, unconditionally switches\\n  the pointer back to A without compensating B\u0027s crc (its remove_crc\\n  is false for the creation path), and finally adds the crc16 to A\u0027s\\n  crc\\n\\nThe CRC is then wrong for both:\\n\\n* claim belongs to A: but CRC is not part of backbone A\u0027s CRC\\n* claim doesn\u0027t belong to B: CRC is still part of backbone B\u0027s CRC\\n\\nThis wrong CRC is never recomputated from the stored claims. For local\\nbackbone claims, this can also not recovered using syncs.\\n\\nTo avoid this, split the functionality in clear separate parts:\\n\\n* new claim which always adds claim CRC to the backbone CRC (but never\\n  changes the already set backbone_gw of the claim back)\\n\\n* update of existing claim which automatically changes the backbone_gw\\n  entry and only updates both backbone CRCs when there was an actual change\"}],\"affected\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"affectedData\":[{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"unaffected\",\"programFiles\":[\"net/batman-adv/bridge_loop_avoidance.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"23721387c409087fd3b97e274f34d3ddc0970b74\",\"lessThan\":\"3d4a9ae2c69c0fe4c3c69587288241243bb7a39b\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"23721387c409087fd3b97e274f34d3ddc0970b74\",\"lessThan\":\"ad982d925f00d860d2467811256ffadcccd9e4a7\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"23721387c409087fd3b97e274f34d3ddc0970b74\",\"lessThan\":\"d5b0e7574da5a485f4dbec32a15911900a4487c2\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"23721387c409087fd3b97e274f34d3ddc0970b74\",\"lessThan\":\"a3e07db74f22a85aeeb51c600da5c98b9cbca11f\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"23721387c409087fd3b97e274f34d3ddc0970b74\",\"lessThan\":\"1d390db003cbb52cdd86837608bff3794501a5ea\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"23721387c409087fd3b97e274f34d3ddc0970b74\",\"lessThan\":\"8bcfa58c4277bff1882a23547c37ab08aa1de12f\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"23721387c409087fd3b97e274f34d3ddc0970b74\",\"lessThan\":\"e54602d9e38db8573f2097d60c7ea8be0a5af1fa\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"23721387c409087fd3b97e274f34d3ddc0970b74\",\"lessThan\":\"08645ab95768b88e2ff85a89211994651710465b\",\"versionType\":\"git\",\"status\":\"affected\"}]},{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"affected\",\"programFiles\":[\"net/batman-adv/bridge_loop_avoidance.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"3.5\",\"status\":\"affected\"},{\"version\":\"0\",\"lessThan\":\"3.5\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"5.10.270\",\"lessThanOrEqual\":\"5.10.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"5.15.221\",\"lessThanOrEqual\":\"5.15.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.1.188\",\"lessThanOrEqual\":\"6.1.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.6.157\",\"lessThanOrEqual\":\"6.6.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.12.110\",\"lessThanOrEqual\":\"6.12.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.18.52\",\"lessThanOrEqual\":\"6.18.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"7.2.6\",\"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/08645ab95768b88e2ff85a89211994651710465b\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/1d390db003cbb52cdd86837608bff3794501a5ea\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/3d4a9ae2c69c0fe4c3c69587288241243bb7a39b\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/8bcfa58c4277bff1882a23547c37ab08aa1de12f\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/a3e07db74f22a85aeeb51c600da5c98b9cbca11f\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/ad982d925f00d860d2467811256ffadcccd9e4a7\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/d5b0e7574da5a485f4dbec32a15911900a4487c2\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/e54602d9e38db8573f2097d60c7ea8be0a5af1fa\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"}]}}",
    "suse_vex": {
      "aggregate_severity": "not set",
      "current_release_date": "2026-09-18T00:10:47Z",
      "cve": "CVE-2026-93203",
      "id": "CVE-2026-93203",
      "initial_release_date": "2026-09-18T00:10:47Z",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2026-93203",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2026-93203.json",
      "version": "2"
    }
  }
}



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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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Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


Detection rules are retrieved from Rulezet.


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