high CVSS 8.4

CVE-2023-52755·Kernel vulnerability

In the Linux kernel, the following vulnerability has been resolved: ksmbd: fix slab out of bounds write in smb_inherit_dacl() slab out-of-bounds write is caused by that offsets is bigger than pntsd allocation size. This patch add the check to validate 3 offsets using allocation size.

Severity
high
Software
Kernel
Fixed in
6.6.3
Published
2024-05-21

Affected versions

From: 6.6

Until: 6.6.3

Fixed in: 6.6.3

How to fix this CVE

Update your Linux kernel to version 6.6.3 or later to patch a critical memory corruption vulnerability in the ksmbd SMB server implementation. The vulnerability allows improper memory writes that could compromise system stability and security. Apply this update immediately, especially if your system exposes SMB shares to untrusted networks.

sudo dnf upgrade kernel kernel-devel

Defensia detects this vulnerability

How to check if you are affected

  1. Step 1: Check your kernel version with `uname -r` and verify it is 6.6.3 or newer
  2. Step 2: Confirm ksmbd is enabled by running `grep -i ksmbd /boot/config-$(uname -r)` — if CONFIG_SMB_SERVER=y or =m, the vulnerable module is active
  3. Step 3: Search system logs for memory-related kernel errors using `dmesg | grep -i 'slab\|out.of.bounds\|ksmbd'`
  4. Step 4: After patching, reboot and re-run `uname -r` to confirm the new kernel version is loaded

FAQ

What is CVE-2023-52755?

CVE-2023-52755 is a heap buffer overflow in the Linux kernel's ksmbd SMB server that occurs during DACL (Discretionary Access Control List) inheritance operations, allowing out-of-bounds writes that can corrupt memory and crash the system.

Is CVE-2023-52755 being actively exploited?

No, this vulnerability is not listed in CISA's Known Exploited Vulnerabilities catalog and no public exploits are currently available, though the high CVSS score (8.4) indicates it should be treated as urgent.

What versions of Kernel are affected by CVE-2023-52755?

Linux kernel versions 6.6 through 6.6.2 are vulnerable; the fix is included in kernel 6.6.3 and later.

How do I check if my server is vulnerable to CVE-2023-52755?

Run `uname -r` to check your kernel version — if it shows 6.6.0, 6.6.1, or 6.6.2, your system is vulnerable. Additionally, confirm ksmbd is loaded with `lsmod | grep ksmbd`.

Does Defensia detect CVE-2023-52755?

Yes — Defensia's CVE advisory scanner compares installed package versions against the NVD database. If the Linux kernel is installed on a monitored server running version 6.6.0–6.6.2, CVE-2023-52755 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-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.
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-2024-36031CVSS 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-2024-38541CVSS 9.8In the Linux kernel, the following vulnerability has been resolved: of: module: add buffer overflow check in of_modalias() In of_modalias(), if the buffer happens to be too small even for the 1st snprintf() call, the len parameter will become negative and str parameter (if not NULL initially) will point beyond the buffer's end. Add the buffer overflow check after the 1st snprintf() call and fix such check after the strlen() call (accounting for the terminating NUL char).

References

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