cbcvebase.
CVE-2026-63888
published 2026-07-19

CVE-2026-63888: 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…

PriorityP355critical9.8CVSS 3.1
AVNACLPRNUINSUCHIHAH
EPSS
0.78%
54.9th percentile
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->conn_ops->DataDigest) { ... rx_size += ISCSI_CRC_LEN; } ... if (conn->conn_ops->DataDigest) { 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->text_in_ptr re-free (double-free) on ERL>0 bad DataDigest drop. On DataDigest mismatch with ErrorRecoveryLevel > 0 the handler silently drops the PDU and lets the initiator plug the CmdSN gap: kfree(text_in); return 0; cmd->text_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->text_in_ptr); cmd->text_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 befo

Affected

55 ranges· showing 25
VendorProductVersion rangeFixed in
linuxlinux——
linuxlinux>= e48354ce078c079996f89d715dfa44814b4eba01 < f7948af0dd03de84079dcd4dc215a69fd6fbb95df7948af0dd03de84079dcd4dc215a69fd6fbb95d
linuxlinux>= e48354ce078c079996f89d715dfa44814b4eba01 < badf178b76b0690851df00f4ca9cf2eb8eb0f963badf178b76b0690851df00f4ca9cf2eb8eb0f963
linuxlinux>= e48354ce078c079996f89d715dfa44814b4eba01 < 6e22a1cdcc8277af4acc43710577157b77a02c5d6e22a1cdcc8277af4acc43710577157b77a02c5d
linuxlinux>= e48354ce078c079996f89d715dfa44814b4eba01 < d3e9b79aa794f7a23e82de4d710e7d2df610e349d3e9b79aa794f7a23e82de4d710e7d2df610e349
linuxlinux>= e48354ce078c079996f89d715dfa44814b4eba01 < ec9f19d52074a191ed1756ed4a7d39fff1a2085cec9f19d52074a191ed1756ed4a7d39fff1a2085c
linuxlinux>= e48354ce078c079996f89d715dfa44814b4eba01 < 89c81d1228c00fa6dd91de6c1c5aa1ef8a7875e389c81d1228c00fa6dd91de6c1c5aa1ef8a7875e3
linuxlinux>= e48354ce078c079996f89d715dfa44814b4eba01 < 5118ea225fe63b44207ba88047e4866e1ea438125118ea225fe63b44207ba88047e4866e1ea43812
linuxlinux>= e48354ce078c079996f89d715dfa44814b4eba01 < 778c2ab142c625a8a8afa570e0f9b7873f445d99778c2ab142c625a8a8afa570e0f9b7873f445d99
linuxlinux_kernel——
ubuntulinux——
ubuntulinux-aws——
ubuntulinux-aws-6.8——
ubuntulinux-aws-fips——
ubuntulinux-azure——
ubuntulinux-azure-6.8——
ubuntulinux-azure-7.0——
ubuntulinux-azure-fde——
ubuntulinux-azure-fde-6.8——
ubuntulinux-azure-fips——
ubuntulinux-fips——
ubuntulinux-gcp——
ubuntulinux-gcp-5.15——
ubuntulinux-gcp-6.8——
ubuntulinux-gcp-7.0——

CVSS provenance

nvdv3.19.8CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
vendor_redhat9.8CRITICAL
vendor_ubuntu9.4CRITICAL
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