{"id":"CVE-2026-63887","summary":"scsi: target: iscsi: Bound iscsi_encode_text_output() appends to rsp_buf","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nscsi: target: iscsi: Bound iscsi_encode_text_output() appends to rsp_buf\n\niscsi_encode_text_output() concatenates \"key=value\\0\" records into\nlogin-\u003ersp_buf, an 8192-byte kzalloc(MAX_KEY_VALUE_PAIRS) buffer\nallocated in iscsit_alloc_login_setup_buffer(). The three sprintf() call\nsites in this function (lines 1398, 1411, 1424 in v7.1-rc2) never check\nthe remaining buffer capacity:\n\n\t*length += sprintf(output_buf, \"%s=%s\", er-\u003ekey, er-\u003evalue);\n\t*length += 1;\n\toutput_buf = textbuf + *length;\n\nThe 8192-byte ceiling at iscsi_target_check_login_request() bounds the\n*input* Login PDU payload, but a single PDU can carry up to 2048 minimal\nfour-byte \"a=b\\0\" pairs, each unknown key expanding to a 16-byte\n\"a=NotUnderstood\\0\" output record via iscsi_add_notunderstood_response().\n2048 * 16 = 32 KiB of output into an 8 KiB buffer, producing a ~24 KiB\nheap overrun in the kmalloc-8k slab.\n\nThe fix introduces a static iscsi_encode_text_record() helper that uses\nsnprintf() with a per-call bounds check against the remaining buffer,\nand threads a u32 textbuf_size parameter through\niscsi_encode_text_output(). Both call sites in\niscsi_target_handle_csg_zero() (PHASE_SECURITY) and\niscsi_target_handle_csg_one() (PHASE_OPERATIONAL) pass\nMAX_KEY_VALUE_PAIRS. On overflow the encoder logs the condition, calls\niscsi_release_extra_responses() to drop queued records, and returns -1;\nboth caller sites now emit ISCSI_STATUS_CLS_INITIATOR_ERR /\nISCSI_LOGIN_STATUS_INIT_ERR via iscsit_tx_login_rsp() before returning,\nso the initiator sees an explicit failed-login response rather than a\nsilent connection drop. (Prior to this patch only the PHASE_OPERATIONAL\ncaller did that; the PHASE_SECURITY caller is converted to the same\nshape.)","modified":"2026-11-01T17:28:11.344697091Z","published":"2026-07-19T14:55:00.114Z","related":["ALSA-2026:54343","ALSA-2026:57253","ALSA-2026:57254","ALSA-2026:63129","SUSE-SU-2026:23477-1","SUSE-SU-2026:23481-1","SUSE-SU-2026:23528-1","SUSE-SU-2026:23529-1","SUSE-SU-2026:23881-1","SUSE-SU-2026:23887-1","SUSE-SU-2026:23897-1","SUSE-SU-2026:23902-1","SUSE-SU-2026:24283-1","SUSE-SU-2026:24284-1","SUSE-SU-2026:24285-1","SUSE-SU-2026:24286-1","SUSE-SU-2026:24287-1","SUSE-SU-2026:24288-1","SUSE-SU-2026:24289-1","SUSE-SU-2026:24290-1","SUSE-SU-2026:24291-1","SUSE-SU-2026:24292-1","SUSE-SU-2026:24293-1","SUSE-SU-2026:24294-1","SUSE-SU-2026:24295-1","SUSE-SU-2026:24296-1","SUSE-SU-2026:24297-1","SUSE-SU-2026:24298-1","SUSE-SU-2026:24299-1","SUSE-SU-2026:24300-1","SUSE-SU-2026:24301-1","SUSE-SU-2026:24302-1","SUSE-SU-2026:24303-1","SUSE-SU-2026:24304-1","SUSE-SU-2026:24305-1","SUSE-SU-2026:24306-1","SUSE-SU-2026:24307-1","SUSE-SU-2026:24308-1","SUSE-SU-2026:24309-1","SUSE-SU-2026:24310-1","SUSE-SU-2026:24311-1","SUSE-SU-2026:24312-1","SUSE-SU-2026:24313-1","SUSE-SU-2026:24327-1","SUSE-SU-2026:24328-1","SUSE-SU-2026:24329-1","SUSE-SU-2026:24330-1","SUSE-SU-2026:24331-1","SUSE-SU-2026:24332-1","SUSE-SU-2026:24333-1","SUSE-SU-2026:24334-1","SUSE-SU-2026:24335-1","SUSE-SU-2026:24336-1","SUSE-SU-2026:24337-1","SUSE-SU-2026:24338-1","SUSE-SU-2026:24339-1","SUSE-SU-2026:24340-1","SUSE-SU-2026:24341-1","SUSE-SU-2026:24342-1","SUSE-SU-2026:24343-1","SUSE-SU-2026:24344-1","SUSE-SU-2026:24345-1","SUSE-SU-2026:24346-1","SUSE-SU-2026:24347-1","SUSE-SU-2026:24348-1","SUSE-SU-2026:24349-1","SUSE-SU-2026:24350-1","SUSE-SU-2026:24351-1","SUSE-SU-2026:24352-1","SUSE-SU-2026:24353-1","SUSE-SU-2026:24354-1","SUSE-SU-2026:24355-1","SUSE-SU-2026:24356-1","SUSE-SU-2026:24357-1","SUSE-SU-2026:24387-1","SUSE-SU-2026:24388-1","SUSE-SU-2026:24389-1","SUSE-SU-2026:24390-1","SUSE-SU-2026:24391-1","SUSE-SU-2026:24392-1","SUSE-SU-2026:24393-1","SUSE-SU-2026:24394-1","SUSE-SU-2026:24395-1","SUSE-SU-2026:24396-1","SUSE-SU-2026:24397-1","SUSE-SU-2026:24398-1","SUSE-SU-2026:24399-1","SUSE-SU-2026:24400-1","SUSE-SU-2026:24401-1","SUSE-SU-2026:24402-1","SUSE-SU-2026:24403-1","SUSE-SU-2026:24415-1","SUSE-SU-2026:24416-1","SUSE-SU-2026:24417-1","SUSE-SU-2026:24419-1","SUSE-SU-2026:24420-1","SUSE-SU-2026:24423-1","SUSE-SU-2026:24424-1","SUSE-SU-2026:24425-1","SUSE-SU-2026:24426-1","SUSE-SU-2026:24427-1","SUSE-SU-2026:24428-1","SUSE-SU-2026:24429-1","SUSE-SU-2026:24430-1","SUSE-SU-2026:24431-1","SUSE-SU-2026:24432-1","SUSE-SU-2026:24433-1","SUSE-SU-2026:24434-1","SUSE-SU-2026:24438-1","SUSE-SU-2026:24439-1","SUSE-SU-2026:24440-1","SUSE-SU-2026:24443-1","SUSE-SU-2026:24444-1","SUSE-SU-2026:24447-1","SUSE-SU-2026:24448-1","SUSE-SU-2026:24449-1","SUSE-SU-2026:24450-1","SUSE-SU-2026:24451-1","SUSE-SU-2026:24452-1","SUSE-SU-2026:24453-1","SUSE-SU-2026:24454-1","SUSE-SU-2026:24455-1","SUSE-SU-2026:24456-1","SUSE-SU-2026:24457-1","SUSE-SU-2026:24458-1","SUSE-SU-2026:4120-1","SUSE-SU-2026:4190-1","SUSE-SU-2026:4254-1","SUSE-SU-2026:4279-1","SUSE-SU-2026:4282-1","SUSE-SU-2026:4284-1","SUSE-SU-2026:4347-1","SUSE-SU-2026:4369-1","SUSE-SU-2026:4595-1","SUSE-SU-2026:4708-1","SUSE-SU-2026:4714-1","SUSE-SU-2026:4718-1","SUSE-SU-2026:4725-1","SUSE-SU-2026:4730-1","SUSE-SU-2026:4733-1","SUSE-SU-2026:4734-1","SUSE-SU-2026:4748-1","SUSE-SU-2026:4749-1","SUSE-SU-2026:4768-1","SUSE-SU-2026:4776-1","SUSE-SU-2026:4785-1","SUSE-SU-2026:4793-1","SUSE-SU-2026:4856-1","SUSE-SU-2026:4888-1","SUSE-SU-2026:4889-1","openSUSE-SU-2026:21910-1"],"database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/63xxx/CVE-2026-63887.json","cna_assigner":"Linux"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/26e4a304b7e6f1338c675d527608d32549c091db"},{"type":"WEB","url":"https://git.kernel.org/stable/c/30bf335e8fe170322080ee001f05ca29c50680b3"},{"type":"WEB","url":"https://git.kernel.org/stable/c/4e9f0c4a645c995bc75c06c7b3644254ffb4c76b"},{"type":"WEB","url":"https://git.kernel.org/stable/c/594a40360012ce5f94c715d5e3b20fa3af7d525a"},{"type":"WEB","url":"https://git.kernel.org/stable/c/b19382dfc6e7dee6d3859ba44b6ca29e97a51627"},{"type":"WEB","url":"https://git.kernel.org/stable/c/bf33e01f88388c43e285492a63e539df6ffed64c"},{"type":"WEB","url":"https://git.kernel.org/stable/c/cb84e974fb172bc71386289f37b78ea679410b39"},{"type":"WEB","url":"https://git.kernel.org/stable/c/efe633e600a0ac68357206fede21b1ac8178f3b8"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/63xxx/CVE-2026-63887.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-63887"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"e48354ce078c079996f89d715dfa44814b4eba01"},{"fixed":"cb84e974fb172bc71386289f37b78ea679410b39"},{"fixed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