Double free in Linux kernel - CVE-2026-63888
Published: July 20, 2026
Vulnerability identifier: #VU138773
CSH Severity: Medium
CVSS v4.0: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Green
CVE-ID: CVE-2026-63888
CWE-ID: CWE-415
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vendor: Linux Foundation
Affected software:
Linux kernel
Linux kernel
Detailed vulnerability description
The vulnerability allows a remote user to cause a denial of service.
The vulnerability exists due to a double free in iscsit_handle_text_cmd() when handling a Text PDU with a bad DataDigest on connections using ErrorRecoveryLevel greater than 0. A remote user can send a specially crafted text request to cause a denial of service.
On hardened kernels the flaw can trigger a remote kernel BUG(), while on non-hardened kernels it can corrupt the slab freelist. A follow-up Text Request on the same ITT or session teardown can free the same pointer again.
How to mitigate CVE-2026-63888
Install security update from vendor's repository.
Sources
- https://git.kernel.org/stable/c/5118ea225fe63b44207ba88047e4866e1ea43812
- https://git.kernel.org/stable/c/6e22a1cdcc8277af4acc43710577157b77a02c5d
- https://git.kernel.org/stable/c/778c2ab142c625a8a8afa570e0f9b7873f445d99
- https://git.kernel.org/stable/c/89c81d1228c00fa6dd91de6c1c5aa1ef8a7875e3
- https://git.kernel.org/stable/c/badf178b76b0690851df00f4ca9cf2eb8eb0f963
- https://git.kernel.org/stable/c/d3e9b79aa794f7a23e82de4d710e7d2df610e349
- https://git.kernel.org/stable/c/ec9f19d52074a191ed1756ed4a7d39fff1a2085c
- https://git.kernel.org/stable/c/f7948af0dd03de84079dcd4dc215a69fd6fbb95d