CVE-2026-64046 (GCVE-0-2026-64046)
Vulnerability from cvelistv5
Published
2026-07-19 15:39
Modified
2026-08-05 12:38
Severity ?
9.8 (Critical) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: net: tls: prevent chain-after-chain in plain text SG Sashiko points out that if end = 0 (start != 0) the current code will create a chain link to content type right after the wrap link: This would create a chain where the wrap link points directly to another chain link. The scatterlist API sg_next iterator does not recursively resolve consecutive chain links. meaning this is illegal input to crypto. The wrapping link is unnecessary if end = 0. end is the entry after the last one used so end = 0 means there's nothing pushed after the wrap: end start i v v v [ ]...[ ][ d ][ d ][ d ][ d ][rsv for wrap] Skip the wrapping in this case. TLS 1.3 can use the "wrapping slot" for it's chaining if end = 0. This avoids the chain-after-chain. Move the wrap chaining before marking END and chaining off content type, that feels like more logical ordering to me, but should not matter from functional perspective.
References
Impacted products
Vendor Product Version
Linux Linux Version: 9aaaa56845a06aeabdd597cbe19492dc01f281ec
Version: 9aaaa56845a06aeabdd597cbe19492dc01f281ec
Version: 9aaaa56845a06aeabdd597cbe19492dc01f281ec
Version: 9aaaa56845a06aeabdd597cbe19492dc01f281ec
Version: 9aaaa56845a06aeabdd597cbe19492dc01f281ec
Version: 9aaaa56845a06aeabdd597cbe19492dc01f281ec
Version: 9aaaa56845a06aeabdd597cbe19492dc01f281ec
Version: 9aaaa56845a06aeabdd597cbe19492dc01f281ec
Version: d529d6c9f7e3aaeac13c4948f79799ccb825f29d
Version: 5.4.14   ≤
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      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: tls: prevent chain-after-chain in plain text SG\n\nSashiko points out that if end = 0 (start != 0) the current\ncode will create a chain link to content type right after\nthe wrap link:\n\n  This would create a chain where the wrap link points directly\n  to another chain link. The scatterlist API sg_next iterator\n  does not recursively resolve consecutive chain links.\n\nmeaning this is illegal input to crypto.\n\nThe wrapping link is unnecessary if end = 0. end is the entry after\nthe last one used so end = 0 means there\u0027s nothing pushed after\nthe wrap:\n\n   end         start            i\n    v            v              v\n  [   ]...[   ][ d ][ d ][ d ][ d ][rsv for wrap]\n\nSkip the wrapping in this case.\n\nTLS 1.3 can use the \"wrapping slot\" for it\u0027s chaining if end = 0.\nThis avoids the chain-after-chain.\n\nMove the wrap chaining before marking END and chaining off content\ntype, that feels like more logical ordering to me, but should not\nmatter from functional perspective."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 9.8,
            "baseSeverity": "CRITICAL",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:N - The bug is in kTLS software TX (`tls_push_record` in `net/tls/tls_sw.c`), reached when encrypting outbound TLS 1.3 records on a connected socket; a remote TLS peer triggers this path on internet-facing servers and L7 proxies (kTLS+sockmap) by causing the host to send TLS responses.\nAC:L - The wrapped `sk_msg` ring state (`end=0`, `start!=0`) needed to hit the chain-after-chain bug is deterministically created via BPF `sk_msg` helpers (`bpf_msg_push_data`/`bpf_msg_pop_data`), which the attacker controls on the local path or can steer on servers whose sockmap programs manipulate messages based on connection traffic.\nPR:N - Exploitation does not require Linux capabilities on the attacking side when targeting a TLS service already running kTLS with sockmap; any unauthenticated remote client that completes a TLS 1.3 handshake and causes record transmission can reach the vulnerable encrypt path.\nUI:N - No victim user action beyond normal automated TLS server/client operation is required; triggering the bug is achieved through crafted network traffic and/or syscall-driven sends on an already-established kTLS socket.\nS:U - Impact is confined to kernel memory corruption and privilege escalation within the same host/kernel security boundary, not a cross-boundary escape such as VM guest-to-host or IOMMU bypass.\nC:H - Passing a scatterlist with consecutive chain links to `crypto_aead_encrypt` is illegal; the crypto scatterwalk treats chain entries as data pages, causing out-of-bounds kernel memory reads and information disclosure primitives.\nI:H - The malformed scatterlist fed to AEAD encryption can cause the crypto layer to write ciphertext to incorrect kernel addresses, providing a memory corruption primitive that can be developed into arbitrary kernel write or code execution.\nA:H - Invalid scatterlist traversal in the crypto path can dereference bogus page pointers and kernel-oops the system; encryption failure also invokes `tls_err_abort`, reliably disrupting the affected TLS connection and potentially the hosting service."
            }
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      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-05T12:38:38.201Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/49a5faaa471ddcd37b6893970c9916eb836e7c31"
        },
        {
          "url": "https://git.kernel.org/stable/c/91359966e247c0244c66d50bbb8e74aefa4321c3"
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        {
          "url": "https://git.kernel.org/stable/c/410351158dfef2d67fea6603680b3a6013c6ed9d"
        },
        {
          "url": "https://git.kernel.org/stable/c/acdc12b71c9aa4be5dcd2c8062753c6d2033e235"
        },
        {
          "url": "https://git.kernel.org/stable/c/929b1548e63ac72e104c07d8ee8cbbeeba2fa89a"
        },
        {
          "url": "https://git.kernel.org/stable/c/af855f4c966afafef74faf8390c7b86568c0d46d"
        },
        {
          "url": "https://git.kernel.org/stable/c/b9c015ef1a7bf1e8dc67f21c6381f36deb2c3a36"
        },
        {
          "url": "https://git.kernel.org/stable/c/ff26a0e8377dec07e4a7230db7675bed1b9a6d03"
        }
      ],
      "title": "net: tls: prevent chain-after-chain in plain text SG",
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  "cveMetadata": {
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-64046",
    "datePublished": "2026-07-19T15:39:31.129Z",
    "dateReserved": "2026-07-19T07:54:57.029Z",
    "dateUpdated": "2026-08-05T12:38:38.201Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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