DEBIAN-CVE-2026-63888

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Source
https://security-tracker.debian.org/tracker/CVE-2026-63888
Import Source
https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2026-63888.json
JSON Data
https://api.test.osv.dev/v1/vulns/DEBIAN-CVE-2026-63888
Upstream
Published
2026-07-19T16:17:05Z
Modified
2026-09-01T16:06:54Z
Severity
  • 9.8 (Critical) CVSS_V3 - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H CVSS Calculator
Summary
[none]
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->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 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>0 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->text_in_ptr after the kfree() in the ERL>0 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.

References

Affected packages

Debian:12 / linux

Package

Name
linux
Purl
pkg:deb/debian/linux?arch=source&distro=bookworm

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0 Unknown introduced version / All previous versions are affected
Fixed
6.1.176-1

Affected versions

6.*
6.1.27-1
6.1.37-1
6.1.38-1
6.1.38-2~bpo11+1
6.1.38-2
6.1.38-3
6.1.38-4~bpo11+1
6.1.38-4
6.1.52-1
6.1.55-1~bpo11+1
6.1.55-1
6.1.64-1
6.1.66-1
6.1.67-1
6.1.69-1~bpo11+1
6.1.69-1
6.1.76-1~bpo11+1
6.1.76-1
6.1.82-1
6.1.85-1
6.1.90-1~bpo11+1
6.1.90-1
6.1.94-1~bpo11+1
6.1.94-1
6.1.98-1
6.1.99-1
6.1.106-1
6.1.106-2
6.1.106-3
6.1.112-1
6.1.115-1
6.1.119-1
6.1.123-1
6.1.124-1
6.1.128-1
6.1.129-1
6.1.133-1
6.1.135-1
6.1.137-1
6.1.139-1
6.1.140-1
6.1.147-1
6.1.148-1
6.1.153-1
6.1.158-1
6.1.159-1
6.1.162-1
6.1.164-1
6.1.170-1
6.1.170-2
6.1.170-3
6.1.172-1
6.1.174-1

Ecosystem specific 

{
    "urgency":  "not yet assigned"
}

Database specific

source 
"https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2026-63888.json"

Debian:13 / linux

Package

Name
linux
Purl
pkg:deb/debian/linux?arch=source&distro=trixie

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0 Unknown introduced version / All previous versions are affected
Fixed
6.12.94-1

Affected versions

6.*
6.12.38-1
6.12.41-1
6.12.43-1~bpo12+1
6.12.43-1
6.12.48-1
6.12.57-1~bpo12+1
6.12.57-1
6.12.63-1~bpo12+1
6.12.63-1
6.12.69-1~bpo12+1
6.12.69-1
6.12.73-1~bpo12+1
6.12.73-1
6.12.74-1
6.12.74-2~bpo12+1
6.12.74-2
6.12.85-1~bpo12+1
6.12.85-1
6.12.86-1~bpo12+1
6.12.86-1
6.12.88-1~bpo12+1
6.12.88-1
6.12.90-1~bpo12+1
6.12.90-1
6.12.90-2~bpo12+1
6.12.90-2
6.12.94-1~bpo12+1

Ecosystem specific 

{
    "urgency":  "not yet assigned"
}

Database specific

source 
"https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2026-63888.json"

Debian:14 / linux

Package

Name
linux
Purl
pkg:deb/debian/linux?arch=source&distro=forky

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0 Unknown introduced version / All previous versions are affected
Fixed
7.0.12-1

Affected versions

6.*
6.12.38-1
6.12.41-1
6.12.43-1~bpo12+1
6.12.43-1
6.12.48-1
6.12.57-1~bpo12+1
6.12.57-1
6.12.63-1~bpo12+1
6.12.63-1
6.12.69-1~bpo12+1
6.12.69-1
6.12.73-1~bpo12+1
6.12.73-1
6.12.74-1
6.12.74-2~bpo12+1
6.12.74-2
6.12.85-1~bpo12+1
6.12.85-1
6.12.86-1~bpo12+1
6.12.86-1
6.12.88-1~bpo12+1
6.12.88-1
6.12.90-1~bpo12+1
6.12.90-1
6.12.90-2~bpo12+1
6.12.90-2
6.12.94-1~bpo12+1
6.12.94-1
6.12.95-1~bpo12+1
6.12.95-1
6.12.96-1
6.12.100-1
6.12.101-1
6.12.105-1
6.12.107-1
6.13~rc6-1~exp1
6.13~rc7-1~exp1
6.13.2-1~exp1
6.13.3-1~exp1
6.13.4-1~exp1
6.13.5-1~exp1
6.13.6-1~exp1
6.13.7-1~exp1
6.13.8-1~exp1
6.13.9-1~exp1
6.13.10-1~exp1
6.13.11-1~exp1
6.14.3-1~exp1
6.14.5-1~exp1
6.14.6-1~exp1
6.15~rc7-1~exp1
6.15-1~exp1
6.15.1-1~exp1
6.15.2-1~exp1
6.15.3-1~exp1
6.15.4-1~exp1
6.15.5-1~exp1
6.15.6-1~exp1
6.16~rc7-1~exp1
6.16-1~exp1
6.16.1-1~exp1
6.16.3-1~bpo13+1
6.16.3-1
6.16.5-1
6.16.6-1
6.16.7-1
6.16.8-1
6.16.9-1
6.16.10-1
6.16.11-1
6.16.12-1~bpo13+1
6.16.12-1
6.16.12-2
6.17.2-1~exp1
6.17.5-1~exp1
6.17.6-1
6.17.7-1
6.17.7-2
6.17.8-1~bpo13+1
6.17.8-1
6.17.9-1
6.17.10-1
6.17.11-1
6.17.12-1
6.17.13-1~bpo13+1
6.17.13-1
6.18~rc4-1~exp1
6.18~rc4-1~exp2
6.18~rc5-1~exp1
6.18~rc6-1~exp1
6.18~rc7-1~exp1
6.18.1-1~exp1
6.18.2-1~exp1
6.18.3-1
6.18.5-1~bpo13+1
6.18.5-1
6.18.8-1
6.18.9-1~bpo13+1
6.18.9-1
6.18.10-1
6.18.12-1~bpo13+1
6.18.12-1
6.18.13-1
6.18.14-1
6.18.15-1~bpo13+1
6.18.15-1
6.19~rc4-1~exp1
6.19~rc5-1~exp1
6.19~rc6-1~exp1
6.19~rc7-1~exp1
6.19~rc8-1~exp1
6.19-1~exp1
6.19.2-1~exp1
6.19.3-1~exp1
6.19.4-1~exp1
6.19.5-1~exp1
6.19.6-1
6.19.6-2~bpo13+1
6.19.6-2
6.19.8-1~bpo13+1
6.19.8-1
6.19.10-1~bpo13+1
6.19.10-1
6.19.11-1~bpo13+1
6.19.11-1
6.19.12-1
6.19.13-1~bpo13+1
6.19.13-1
6.19.14-1~bpo13+1
6.19.14-1
7.*
7.0-1~exp1
7.0.1-1~exp1
7.0.3-1
7.0.4-1~bpo13+1
7.0.4-1
7.0.7-1~bpo13+1
7.0.7-1
7.0.9-1~bpo13+1
7.0.9-1
7.0.10-1~bpo13+1
7.0.10-1

Ecosystem specific 

{
    "urgency":  "not yet assigned"
}

Database specific

source 
"https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2026-63888.json"