CVE-2026-43336 (GCVE-0-2026-43336)
Vulnerability from cvelistv5
Published
2026-05-08 13:31
Modified
2026-08-05 12:27
Severity ?
7.5 (High) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
Summary
In the Linux kernel, the following vulnerability has been resolved: lib/crypto: chacha: Zeroize permuted_state before it leaves scope Since the ChaCha permutation is invertible, the local variable 'permuted_state' is sufficient to compute the original 'state', and thus the key, even after the permutation has been done. While the kernel is quite inconsistent about zeroizing secrets on the stack (and some prominent userspace crypto libraries don't bother at all since it's not guaranteed to work anyway), the kernel does try to do it as a best practice, especially in cases involving the RNG. Thus, explicitly zeroize 'permuted_state' before it goes out of scope.
References
Impacted products
Vendor Product Version
Linux Linux Version: c08d0e647305c3f8f640010a56c9e4bafb9488d3
Version: c08d0e647305c3f8f640010a56c9e4bafb9488d3
Version: c08d0e647305c3f8f640010a56c9e4bafb9488d3
Version: c08d0e647305c3f8f640010a56c9e4bafb9488d3
Version: c08d0e647305c3f8f640010a56c9e4bafb9488d3
Version: c08d0e647305c3f8f640010a56c9e4bafb9488d3
Version: c08d0e647305c3f8f640010a56c9e4bafb9488d3
Version: c08d0e647305c3f8f640010a56c9e4bafb9488d3
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "lib/crypto/chacha-block-generic.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
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          "vendor": "Linux",
          "versions": [
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              "version": "4.2"
            },
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              "status": "unaffected",
              "version": "0",
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              "version": "5.10.253",
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              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.0",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
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                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "5.10.253",
                  "versionStartIncluding": "4.2",
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                  "versionEndExcluding": "7.0",
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              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nlib/crypto: chacha: Zeroize permuted_state before it leaves scope\n\nSince the ChaCha permutation is invertible, the local variable\n\u0027permuted_state\u0027 is sufficient to compute the original \u0027state\u0027, and thus\nthe key, even after the permutation has been done.\n\nWhile the kernel is quite inconsistent about zeroizing secrets on the\nstack (and some prominent userspace crypto libraries don\u0027t bother at all\nsince it\u0027s not guaranteed to work anyway), the kernel does try to do it\nas a best practice, especially in cases involving the RNG.\n\nThus, explicitly zeroize \u0027permuted_state\u0027 before it goes out of scope."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 7.5,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:N - Network-facing kernel crypto users such as IPsec ESP and WireGuard can drive ChaCha/ChaCha20-Poly1305 from inbound packets into the affected generic block code. This is a reasonable deployment scenario for the affected library crypto code.\nAC:L - Triggering the affected function is deterministic once a configured network crypto endpoint processes a packet; there is no race or fragile heap/layout condition in the bug mechanism. When uncertain, the lower-complexity option is selected.\nPR:N - A remote sender does not need a local account or kernel privilege to send packets to a configured ESP/WireGuard endpoint and cause pre-authentication or authentication-check crypto processing. Local configuration of the endpoint is an environmental precondition, not attacker privilege.\nUI:N - No victim user action is required once the affected kernel subsystem is configured and reachable. The attacker can trigger processing by sending packets or requests directly.\nS:U - The vulnerable component and impacted secrets are within the kernel\u2019s own security authority. This is not a VM escape, IOMMU bypass, or cross-scope boundary violation.\nC:H - The stale `permuted_state` is invertible back to the original ChaCha state and therefore key-equivalent, including for kernel crypto and RNG users. Exposure of that stack data can compromise full cryptographic keys or RNG state, so confidentiality impact is high.\nI:N - The bug is failure to clear sensitive stack data and does not provide a write primitive or data modification path. No integrity impact is directly caused.\nA:N - The issue does not corrupt memory, dereference invalid pointers, deadlock, or otherwise crash the kernel. No availability impact is directly caused."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-05T12:27:19.605Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/e90ee961af515a484f091678ce58a4c3f7b73b02"
        },
        {
          "url": "https://git.kernel.org/stable/c/b416a4245f04a450c67a13e6d96056c37c5b33fe"
        },
        {
          "url": "https://git.kernel.org/stable/c/bd62d9b44464a6c20a34a74068e7a784d0afa04a"
        },
        {
          "url": "https://git.kernel.org/stable/c/066c760acead1fb743bae294dbd89f479ae43b9b"
        },
        {
          "url": "https://git.kernel.org/stable/c/1d761e5a7340c46479fb2399598f331e4fe2c633"
        },
        {
          "url": "https://git.kernel.org/stable/c/1933249263c3a98df79992f61a566476e4163bcc"
        },
        {
          "url": "https://git.kernel.org/stable/c/91999af43ca2125e3b2c18fcfc02912ada02efc3"
        },
        {
          "url": "https://git.kernel.org/stable/c/e5046823f8fa3677341b541a25af2fcb99a5b1e0"
        }
      ],
      "title": "lib/crypto: chacha: Zeroize permuted_state before it leaves scope",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-43336",
    "datePublished": "2026-05-08T13:31:22.280Z",
    "dateReserved": "2026-05-01T14:12:56.002Z",
    "dateUpdated": "2026-08-05T12:27:19.605Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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