high CVSS 7.8

CVE-2024-26928·Kernel vulnerability

In the Linux kernel, the following vulnerability has been resolved: smb: client: fix potential UAF in cifs_debug_files_proc_show() Skip sessions that are being teared down (status == SES_EXITING) to avoid UAF.

Severity
high
Software
Kernel
Fixed in
6.8.5
Published
2024-04-28

Affected versions

From: 6.7

Until: 6.8.5

Fixed in: 6.8.5

How to fix this CVE

Update your Linux kernel to version 6.8.5 or later to patch a use-after-free vulnerability in the CIFS debug file handler. This issue could allow local attackers with limited privileges to trigger memory corruption by accessing debug interfaces during SMB session teardown. Kernel updates should be applied promptly and followed by a system reboot to activate the patched version.

sudo dnf update kernel kernel-devel && sudo reboot

Defensia detects this vulnerability

How to check if you are affected

  1. Step 1: Check installed kernel version with 'uname -r' and compare against 6.8.5; versions 6.7.x through 6.8.4 are vulnerable
  2. Step 2: Verify CIFS/SMB client functionality is active by checking 'grep -i cifs /proc/filesystems' and 'mount | grep cifs' for active CIFS mounts
  3. Step 3: Search kernel logs for UAF indicators: 'dmesg | grep -i "use-after-free\|cifs_debug\|UAF"' and check '/var/log/kern.log' for memory corruption messages during SMB session activity
  4. Step 4: After patching, confirm with 'uname -r' that kernel version is 6.8.5 or later, then retest CIFS mount operations to ensure stability

FAQ

What is CVE-2024-26928?

This vulnerability is a use-after-free (UAF) flaw in the Linux kernel's CIFS debug handler that occurs when reading session information while SMB sessions are being torn down. An attacker with local user privileges can trigger memory corruption by accessing debug files during session cleanup.

Is CVE-2024-26928 being actively exploited?

No, according to CISA's Known Exploited Vulnerabilities catalog, CVE-2024-26928 is not currently being exploited in the wild, and no public exploits are available.

What versions of Kernel are affected by CVE-2024-26928?

Linux kernel versions 6.7 through 6.8.4 are vulnerable. Version 6.8.5 and later include the necessary patches.

How do I check if my server is vulnerable to CVE-2024-26928?

Run 'uname -r' to display your kernel version; if it shows 6.7.x, 6.8.0, 6.8.1, 6.8.2, 6.8.3, or 6.8.4, your system is vulnerable and requires immediate patching.

Does Defensia detect CVE-2024-26928?

Yes — Defensia's CVE advisory scanner compares installed package versions against the NVD database. If the Linux kernel is installed on a monitored server, CVE-2024-26928 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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