{ "schemaVersion": 1, "attribution": [ { "source": "CISA Known Exploited Vulnerabilities", "url": "https://www.cisa.gov/known-exploited-vulnerabilities-catalog", "licence": "US government work" }, { "source": "GitHub Advisory Database", "url": "https://github.com/advisories", "licence": "CC BY 4.0" }, { "source": "Have I Been Pwned", "url": "https://haveibeenpwned.com/", "licence": "CC BY 4.0" }, { "source": "CVE Program (CVE records)", "url": "https://www.cve.org/Legal/TermsOfUse", "licence": "CVE Terms of Use", "notice": "Copyright © 1999-2026, The MITRE Corporation. CVE is a trademark and the CVE logo is a registered trademark of The MITRE Corporation.", "terms": "CVE Usage: MITRE hereby grants you a perpetual, worldwide, non-exclusive, no-charge, royalty-free, irrevocable copyright license to reproduce, prepare derivative works of, publicly display, publicly perform, sublicense, and distribute Common Vulnerabilities and Exposures (CVE™). Any copy you make for such purposes is authorized provided that you reproduce MITRE's copyright designation and this license in any such copy." }, { "source": "FIRST EPSS", "url": "https://www.first.org/epss/", "licence": "free to use; FIRST requests attribution" } ], "record": { "id": "CVE-2026-63888", "sourceURL": "https://www.cve.org/CVERecord?id=CVE-2026-63888", "idYear": 2026, "status": "PUBLISHED", "publishedAt": "2026-07-19T14:55:00.803Z", "updatedAt": "2026-10-19T20:17:54.825Z", "importedAt": "2026-10-24T01:58:20.586Z", "snapshot": { "id": "cve_2026-10-24_midnight_baseline", "at": "2026-10-24T00:00:00.000Z", "source": "https://github.com/CVEProject/cvelistV5/releases/tag/cve_2026-10-24_0100Z" }, "facts": { "title": "scsi: target: iscsi: Fix CRC overread and double-free in iscsit_handle_text_cmd()", "summary": "In the Linux kernel, the following vulnerability has been resolved:\n\nscsi: target: iscsi: Fix CRC overread and double-free in iscsit_handle_text_cmd()\n\nTwo latent bugs in the Text-phase handler, both present since the\noriginal LIO integration in commit e48354ce078c (\"iscsi-target: Add\niSCSI fabric support for target v4.1\"):\n\n1) DataDigest CRC buffer overread (4 bytes past text_in).\n\n text_in is kzalloc()'d at ALIGN(payload_length, 4). rx_size is then\n incremented by ISCSI_CRC_LEN to make room for the received DataDigest\n in the iovec, but the same (now-bumped) rx_size is passed as the\n buffer length to iscsit_crc_buf():\n\n if (conn->conn_ops->DataDigest) {\n ...\n rx_size += ISCSI_CRC_LEN;\n }\n ...\n if (conn->conn_ops->DataDigest) {\n data_crc = iscsit_crc_buf(text_in, rx_size, 0, NULL);\n\n iscsit_crc_buf() walks rx_size bytes of text_in with crc32c(), so\n when DataDigest is negotiated it reads 4 bytes past the end of the\n text_in allocation. KASAN reproduces this directly on the unpatched\n mainline tree as slab-out-of-bounds in crc32c() called from the Text\n PDU path. The OOB bytes feed crc32c() and are then compared against\n the initiator-supplied checksum, so the value does not flow back to\n the attacker, but the kernel does read past the buffer on every Text\n PDU with DataDigest=CRC32C.\n\n Fix by passing the actual padded payload length\n (ALIGN(payload_length, 4)) that was used for the kzalloc().\n\n2) Stale cmd->text_in_ptr re-free (double-free) on ERL>0 bad DataDigest\n drop.\n\n On DataDigest mismatch with ErrorRecoveryLevel > 0 the handler\n silently drops the PDU and lets the initiator plug the CmdSN gap:\n\n kfree(text_in);\n return 0;\n\n cmd->text_in_ptr still points at the freed buffer. The next Text\n Request on the same ITT re-enters iscsit_setup_text_cmd(), which\n unconditionally does\n\n kfree(cmd->text_in_ptr);\n cmd->text_in_ptr = NULL;\n\n freeing the same pointer a second time. Session teardown via\n iscsit_release_cmd() has the same shape and hits the same double-free\n if the connection is dropped before a second Text Request arrives.\n\n On an unmodified mainline tree the bug-1 CRC overread fires first on\n the initial valid Text Request and perturbs the subsequent state, so\n #4 was isolated by building a kernel with only the bug-1 hunk of this\n patch applied plus temporary printk() observability around the three\n relevant kfree() sites. The observability prints are not part of\n this patch. On that build, a three-PDU Text Request sequence after\n login produces two back-to-back splats:\n\n BUG: KASAN: double-free in iscsit_setup_text_cmd+0x??\n BUG: KASAN: double-free in iscsit_release_cmd+0x??\n\n showing the same pointer freed in the ERL>0 drop path and again in\n iscsit_setup_text_cmd() (next Text Request on the same ITT) and once\n more in iscsit_release_cmd() (session teardown). On distro kernels\n with CONFIG_SLAB_FREELIST_HARDENED=y (default) the double-free\n becomes a remote kernel BUG(); on non-hardened kernels it corrupts\n the slab freelist.\n\n Fix by clearing cmd->text_in_ptr after the kfree() in the ERL>0 drop\n path. With both hunks applied #4 is directly observable on the stock\n tree without observability printks; fixing bug-1 alone would mask #4\n less, not more, so the hunks are submitted together.\n\nBoth fixes are one-liners. The Text PDU state machine is unchanged and\nthe wire protocol is unaffected.", "affected": [ { "vendor": "Linux", "product": "Linux", "defaultStatus": "unaffected", "versions": [ { "version": "e48354ce078c079996f89d715dfa44814b4eba01", "status": "affected", "versionType": "git", "lessThan": "f7948af0dd03de84079dcd4dc215a69fd6fbb95d" }, { "version": "e48354ce078c079996f89d715dfa44814b4eba01", "status": "affected", "versionType": "git", "lessThan": "badf178b76b0690851df00f4ca9cf2eb8eb0f963" }, { "version": "e48354ce078c079996f89d715dfa44814b4eba01", "status": "affected", "versionType": "git", "lessThan": "6e22a1cdcc8277af4acc43710577157b77a02c5d" }, { "version": "e48354ce078c079996f89d715dfa44814b4eba01", "status": "affected", "versionType": "git", "lessThan": "d3e9b79aa794f7a23e82de4d710e7d2df610e349" }, { "version": "e48354ce078c079996f89d715dfa44814b4eba01", "status": "affected", "versionType": "git", "lessThan": "ec9f19d52074a191ed1756ed4a7d39fff1a2085c" }, { "version": "e48354ce078c079996f89d715dfa44814b4eba01", "status": "affected", "versionType": "git", "lessThan": "89c81d1228c00fa6dd91de6c1c5aa1ef8a7875e3" }, { "version": "e48354ce078c079996f89d715dfa44814b4eba01", "status": "affected", "versionType": "git", "lessThan": "5118ea225fe63b44207ba88047e4866e1ea43812" }, { "version": "e48354ce078c079996f89d715dfa44814b4eba01", "status": "affected", "versionType": "git", "lessThan": "778c2ab142c625a8a8afa570e0f9b7873f445d99" } ] }, { "vendor": "Linux", "product": "Linux", "defaultStatus": "affected", "versions": [ { "version": "3.1", "status": "affected" }, { "version": "0", "status": "unaffected", "versionType": "semver", "lessThan": "3.1" }, { "version": "5.10.259", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "5.10.*" }, { "version": "5.15.210", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "5.15.*" }, { "version": "6.1.176", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "6.1.*" }, { "version": "6.6.143", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "6.6.*" }, { "version": "6.12.93", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "6.12.*" }, { "version": "6.18.35", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "6.18.*" }, { "version": "7.0.12", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "7.0.*" }, { "version": "7.1", "status": "unaffected", "versionType": "original_commit_for_fix", "lessThanOrEqual": "*" } ] } ] } } }