high CVSS 7.1

CVE-2024-26954·Kernel vulnerability

In the Linux kernel, the following vulnerability has been resolved: ksmbd: fix slab-out-of-bounds in smb_strndup_from_utf16() If ->NameOffset of smb2_create_req is smaller than Buffer offset of smb2_create_req, slab-out-of-bounds read can happen from smb2_open. This patch set the minimum value of the name offset to the buffer offset to validate name length of smb2_create_req().

Severity
high
Software
Kernel
Fixed in
6.8.3
Published
2024-05-01

Affected versions

From: 6.8

Until: 6.8.3

Fixed in: 6.8.3

How to fix this CVE

Update your Linux kernel to version 6.8.3 or later to patch a memory safety issue in the ksmbd SMB server implementation. The vulnerability allows local attackers to read out-of-bounds kernel memory by sending malformed SMB2 create requests with invalid name offset values. Immediate patching is recommended for systems exposing SMB services to untrusted local users.

sudo dnf update kernel kernel-headers

Defensia detects this vulnerability

How to check if you are affected

  1. Check kernel version: uname -r — confirm version is 6.8.0 through 6.8.2 (vulnerable range)
  2. Verify ksmbd is enabled: grep -i ksmbd /boot/config-$(uname -r) — look for CONFIG_SMB_SERVER=y or CONFIG_SMB_SERVER=m
  3. Check for ksmbd service status: systemctl status ksmbd or ps aux | grep ksmbd — confirm if SMB server is running
  4. Verify patch applied: uname -r should show 6.8.3 or later after kernel update and reboot

FAQ

What is CVE-2024-26954?

This is a memory safety vulnerability in the Linux kernel's ksmbd (kernel SMB server) module where improper validation of SMB2 create request parameters allows local attackers to trigger out-of-bounds memory reads, potentially exposing sensitive kernel data.

Is CVE-2024-26954 being actively exploited?

No — this vulnerability is not listed on CISA's Known Exploited Vulnerabilities (KEV) catalog and no public exploits are currently available, though it remains a high-priority patch due to its memory safety implications.

What versions of Kernel are affected by CVE-2024-26954?

Linux kernel versions 6.8.0 through 6.8.2 are vulnerable. Version 6.8.3 and all later versions include the security fix.

How do I check if my server is vulnerable to CVE-2024-26954?

Run `uname -r` and `grep CONFIG_SMB_SERVER /boot/config-$(uname -r)` — if your kernel is 6.8.0–6.8.2 and ksmbd is compiled in (=y or =m), your system is vulnerable.

Does Defensia detect CVE-2024-26954?

Yes — Defensia's CVE advisory scanner compares installed package versions against the NVD database. If Kernel is installed on a monitored server, CVE-2024-26954 will appear in your dashboard with remediation steps.

Related Kernel CVEs

CVE-2024-42256CVSS 9.8In the Linux kernel, the following vulnerability has been resolved: cifs: Fix server re-repick on subrequest retry When a subrequest is marked for needing retry, netfs will call cifs_prepare_write() which will make cifs repick the server for the op before renegotiating credits; it then calls cifs_issue_write() which invokes smb2_async_writev() - which re-repicks the server. If a different server is then selected, this causes the increment of server->in_flight to happen against one record and the decrement to happen against another, leading to misaccounting. Fix this by just removing the repick code in smb2_async_writev(). As this is only called from netfslib-driven code, cifs_prepare_write() should always have been called first, and so server should never be NULL and the preparatory step is repeated in the event that we do a retry. The problem manifests as a warning looking something like: WARNING: CPU: 4 PID: 72896 at fs/smb/client/smb2ops.c:97 smb2_add_credits+0x3f0/0x9e0 [cifs] ... RIP: 0010:smb2_add_credits+0x3f0/0x9e0 [cifs] ... smb2_writev_callback+0x334/0x560 [cifs] cifs_demultiplex_thread+0x77a/0x11b0 [cifs] kthread+0x187/0x1d0 ret_from_fork+0x34/0x60 ret_from_fork_asm+0x1a/0x30 Which may be triggered by a number of different xfstests running against an Azure server in multichannel mode. generic/249 seems the most repeatable, but generic/215, generic/249 and generic/308 may also show it.
CVE-2024-36031CVSS 9.8In the Linux kernel, the following vulnerability has been resolved: keys: Fix overwrite of key expiration on instantiation The expiry time of a key is unconditionally overwritten during instantiation, defaulting to turn it permanent. This causes a problem for DNS resolution as the expiration set by user-space is overwritten to TIME64_MAX, disabling further DNS updates. Fix this by restoring the condition that key_set_expiry is only called when the pre-parser sets a specific expiry.
CVE-2024-38612CVSS 9.8In the Linux kernel, the following vulnerability has been resolved: ipv6: sr: fix invalid unregister error path The error path of seg6_init() is wrong in case CONFIG_IPV6_SEG6_LWTUNNEL is not defined. In that case if seg6_hmac_init() fails, the genl_unregister_family() isn't called. This issue exist since commit 46738b1317e1 ("ipv6: sr: add option to control lwtunnel support"), and commit 5559cea2d5aa ("ipv6: sr: fix possible use-after-free and null-ptr-deref") replaced unregister_pernet_subsys() with genl_unregister_family() in this error path.
CVE-2024-38623CVSS 9.8In the Linux kernel, the following vulnerability has been resolved: fs/ntfs3: Use variable length array instead of fixed size Should fix smatch warning: ntfs_set_label() error: __builtin_memcpy() 'uni->name' too small (20 vs 256)
CVE-2021-47548CVSS 9.8In the Linux kernel, the following vulnerability has been resolved: ethernet: hisilicon: hns: hns_dsaf_misc: fix a possible array overflow in hns_dsaf_ge_srst_by_port() The if statement: if (port >= DSAF_GE_NUM) return; limits the value of port less than DSAF_GE_NUM (i.e., 8). However, if the value of port is 6 or 7, an array overflow could occur: port_rst_off = dsaf_dev->mac_cb[port]->port_rst_off; because the length of dsaf_dev->mac_cb is DSAF_MAX_PORT_NUM (i.e., 6). To fix this possible array overflow, we first check port and if it is greater than or equal to DSAF_MAX_PORT_NUM, the function returns.

References

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