scsi: target: iscsi: Bound iscsi_encode_text_output() appends to rsp_buf
In the Linux kernel, the following vulnerability has been resolved: scsi: target: iscsi: Bound iscsi_encode_text_output() appends to rsp_buf iscsi_encode_text_output() concatenates "key=value\0" records into login->rsp_buf, an 8192-byte kzalloc(MAX_KEY_VALUE_PAIRS) buffer allocated in iscsit_alloc_login_setup_buffer(). The three sprintf() call sites in this function (lines 1398, 1411, 1424 in v7.1-rc2) never check the remaining buffer capacity: *length += sprintf(output_buf, "%s=%s", er->key, er->value); *length += 1; output_buf = textbuf + *length; The 8192-byte ceiling at iscsi_target_check_login_request() bounds the *input* Login PDU payload, but a single PDU can carry up to 2048 minimal four-byte "a=b\0" pairs, each unknown key expanding to a 16-byte "a=NotUnderstood\0" output record via iscsi_add_notunderstood_response(). 2048 * 16 = 32 KiB of output into an 8 KiB buffer, producing a ~24 KiB heap overrun in the kmalloc-8k slab. The fix introduces a static iscsi_encode_text_record() helper that uses snprintf() with a per-call bounds check against the remaining buffer, and threads a u32 textbuf_size parameter through iscsi_encode_text_output(). Both call sites in iscsi_target_handle_csg_zero() (PHASE_SECURITY) and iscsi_target_handle_csg_one() (PHASE_OPERATIONAL) pass MAX_KEY_VALUE_PAIRS. On overflow the encoder logs the condition, calls iscsi_release_extra_responses() to drop queued records, and returns -1; both caller sites now emit ISCSI_STATUS_CLS_INITIATOR_ERR / ISCSI
CVE-2026-63887
Primary source · Revision 1
Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.
Security context
Source reference: cve:CVE-2026-63887
Linux
Source reference: /containers/cna/affected/0/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Linux
Source reference: /containers/cna/affected/1/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Structured affected-version data
Original package identities and version rules from this source.
[
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "e48354ce078c079996f89d715dfa44814b4eba01",
"lessThan": "cb84e974fb172bc71386289f37b78ea679410b39",
"versionType": "git"
},
{
"status": "affected",
"version": "e48354ce078c079996f89d715dfa44814b4eba01",
"lessThan": "b19382dfc6e7dee6d3859ba44b6ca29e97a51627",
"versionType": "git"
},
{
"status": "affected",
"version": "e48354ce078c079996f89d715dfa44814b4eba01",
"lessThan": "efe633e600a0ac68357206fede21b1ac8178f3b8",
"versionType": "git"
},
{
"status": "affected",
"version": "e48354ce078c079996f89d715dfa44814b4eba01",
"lessThan": "4e9f0c4a645c995bc75c06c7b3644254ffb4c76b",
"versionType": "git"
},
{
"status": "affected",
"version": "e48354ce078c079996f89d715dfa44814b4eba01",
"lessThan": "30bf335e8fe170322080ee001f05ca29c50680b3",
"versionType": "git"
},
{
"status": "affected",
"version": "e48354ce078c079996f89d715dfa44814b4eba01",
"lessThan": "594a40360012ce5f94c715d5e3b20fa3af7d525a",
"versionType": "git"
},
{
"status": "affected",
"version": "e48354ce078c079996f89d715dfa44814b4eba01",
"lessThan": "26e4a304b7e6f1338c675d527608d32549c091db",
"versionType": "git"
},
{
"status": "affected",
"version": "e48354ce078c079996f89d715dfa44814b4eba01",
"lessThan": "bf33e01f88388c43e285492a63e539df6ffed64c",
"versionType": "git"
}
],
"programFiles": [
"drivers/target/iscsi/iscsi_target_nego.c",
"drivers/target/iscsi/iscsi_target_parameters.c",
"drivers/target/iscsi/iscsi_target_parameters.h"
],
"defaultStatus": "unaffected"
},
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "3.1"
},
{
"status": "unaffected",
"version": "0",
"lessThan": "3.1",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "5.10.259",
"versionType": "semver",
"lessThanOrEqual": "5.10.*"
},
{
"status": "unaffected",
"version": "5.15.210",
"versionType": "semver",
"lessThanOrEqual": "5.15.*"
},
{
"status": "unaffected",
"version": "6.1.176",
"versionType": "semver",
"lessThanOrEqual": "6.1.*"
},
{
"status": "unaffected",
"version": "6.6.143",
"versionType": "semver",
"lessThanOrEqual": "6.6.*"
},
{
"status": "unaffected",
"version": "6.12.93",
"versionType": "semver",
"lessThanOrEqual": "6.12.*"
},
{
"status": "unaffected",
"version": "6.18.35",
"versionType": "semver",
"lessThanOrEqual": "6.18.*"
},
{
"status": "unaffected",
"version": "7.0.12",
"versionType": "semver",
"lessThanOrEqual": "7.0.*"
},
{
"status": "unaffected",
"version": "7.1",
"versionType": "original_commit_for_fix",
"lessThanOrEqual": "*"
}
],
"programFiles": [
"drivers/target/iscsi/iscsi_target_nego.c",
"drivers/target/iscsi/iscsi_target_parameters.c",
"drivers/target/iscsi/iscsi_target_parameters.h"
],
"defaultStatus": "affected"
}
]- Related CVEs
- CVE-2026-63887
Source reference:
/cveMetadata/cveId
Publisher severity
critical
Source reference: /containers/cna/metrics
- Event
- #40883 · Revision 1
- Added to Heist Feed
- Publisher date