{
  "affected": [
    {
      "ecosystem_specific": {
        "urgency": "not yet assigned"
      },
      "package": {
        "ecosystem": "Debian:12",
        "name": "linux"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "6.1.176-1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "ecosystem_specific": {
        "urgency": "not yet assigned"
      },
      "package": {
        "ecosystem": "Debian:13",
        "name": "linux"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "6.12.94-1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "ecosystem_specific": {
        "urgency": "not yet assigned"
      },
      "package": {
        "ecosystem": "Debian:14",
        "name": "linux"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "7.0.12-1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "details": "In the Linux kernel, the following vulnerability has been resolved:  scsi: target: iscsi: Fix CRC overread and double-free in iscsit_handle_text_cmd()  Two latent bugs in the Text-phase handler, both present since the original LIO integration in commit e48354ce078c (\"iscsi-target: Add iSCSI fabric support for target v4.1\"):  1) DataDigest CRC buffer overread (4 bytes past text_in).     text_in is kzalloc()'d at ALIGN(payload_length, 4).  rx_size is then    incremented by ISCSI_CRC_LEN to make room for the received DataDigest    in the iovec, but the same (now-bumped) rx_size is passed as the    buffer length to iscsit_crc_buf():         if (conn-\u003econn_ops-\u003eDataDigest) {                ...                rx_size += ISCSI_CRC_LEN;        }        ...        if (conn-\u003econn_ops-\u003eDataDigest) {                data_crc = iscsit_crc_buf(text_in, rx_size, 0, NULL);     iscsit_crc_buf() walks rx_size bytes of text_in with crc32c(), so    when DataDigest is negotiated it reads 4 bytes past the end of the    text_in allocation.  KASAN reproduces this directly on the unpatched    mainline tree as slab-out-of-bounds in crc32c() called from the Text    PDU path.  The OOB bytes feed crc32c() and are then compared against    the initiator-supplied checksum, so the value does not flow back to    the attacker, but the kernel does read past the buffer on every Text    PDU with DataDigest=CRC32C.     Fix by passing the actual padded payload length    (ALIGN(payload_length, 4)) that was used for the kzalloc().  2) Stale cmd-\u003etext_in_ptr re-free (double-free) on ERL\u003e0 bad DataDigest    drop.     On DataDigest mismatch with ErrorRecoveryLevel \u003e 0 the handler    silently drops the PDU and lets the initiator plug the CmdSN gap:                 kfree(text_in);                return 0;     cmd-\u003etext_in_ptr still points at the freed buffer.  The next Text    Request on the same ITT re-enters iscsit_setup_text_cmd(), which    unconditionally does         kfree(cmd-\u003etext_in_ptr);        cmd-\u003etext_in_ptr = NULL;     freeing the same pointer a second time.  Session teardown via    iscsit_release_cmd() has the same shape and hits the same double-free    if the connection is dropped before a second Text Request arrives.     On an unmodified mainline tree the bug-1 CRC overread fires first on    the initial valid Text Request and perturbs the subsequent state, so    #4 was isolated by building a kernel with only the bug-1 hunk of this    patch applied plus temporary printk() observability around the three    relevant kfree() sites.  The observability prints are not part of    this patch.  On that build, a three-PDU Text Request sequence after    login produces two back-to-back splats:         BUG: KASAN: double-free in iscsit_setup_text_cmd+0x??        BUG: KASAN: double-free in iscsit_release_cmd+0x??     showing the same pointer freed in the ERL\u003e0 drop path and again in    iscsit_setup_text_cmd() (next Text Request on the same ITT) and once    more in iscsit_release_cmd() (session teardown).  On distro kernels    with CONFIG_SLAB_FREELIST_HARDENED=y (default) the double-free    becomes a remote kernel BUG(); on non-hardened kernels it corrupts    the slab freelist.     Fix by clearing cmd-\u003etext_in_ptr after the kfree() in the ERL\u003e0 drop    path.  With both hunks applied #4 is directly observable on the stock    tree without observability printks; fixing bug-1 alone would mask #4    less, not more, so the hunks are submitted together.  Both fixes are one-liners.  The Text PDU state machine is unchanged and the wire protocol is unaffected.",
  "id": "DEBIAN-CVE-2026-63888",
  "modified": "2026-09-14T16:47:47.903866884Z",
  "published": "2026-07-19T16:17:05.997Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://security-tracker.debian.org/tracker/CVE-2026-63888"
    }
  ],
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ],
  "upstream": [
    "CVE-2026-63888"
  ]
}