high CVSS 7

CVE-2024-39503·Kernel vulnerability

In the Linux kernel, the following vulnerability has been resolved: netfilter: ipset: Fix race between namespace cleanup and gc in the list:set type Lion Ackermann reported that there is a race condition between namespace cleanup in ipset and the garbage collection of the list:set type. The namespace cleanup can destroy the list:set type of sets while the gc of the set type is waiting to run in rcu cleanup. The latter uses data from the destroyed set which thus leads use after free. The patch contains the following parts: - When destroying all sets, first remove the garbage collectors, then wait if needed and then destroy the sets. - Fix the badly ordered "wait then remove gc" for the destroy a single set case. - Fix the missing rcu locking in the list:set type in the userspace test case. - Use proper RCU list handlings in the list:set type. The patch depends on c1193d9bbbd3 (netfilter: ipset: Add list flush to cancel_gc).

Severity
high
Software
Kernel
Fixed in
6.9.6
Published
2024-07-12

Affected versions

From: 6.8.1

Until: 6.9.6

Fixed in: 6.9.6

How to fix this CVE

Update your Linux kernel to version 6.9.6 or later to resolve a critical race condition in netfilter's ipset list:set type that can lead to use-after-free memory corruption. This vulnerability occurs when namespace cleanup runs concurrently with garbage collection, destroying set data while it is still being accessed. Apply the kernel update immediately to all affected systems and reboot to ensure the patched version is active.

sudo dnf update kernel kernel-devel

Defensia detects this vulnerability

How to check if you are affected

  1. Check your installed kernel version: uname -r — ensure it is 6.9.6 or later; if between 6.8.1 and 6.9.5, your system is vulnerable
  2. Verify ipset is loaded and in use: lsmod | grep ip_set — this confirms the vulnerable netfilter module is active
  3. Check for ipset rules or sets in use: ipset list — if output is non-empty, the vulnerable code path can be triggered during namespace operations
  4. After patching, confirm the new kernel is booted: uname -r should show 6.9.6 or later, and compare with dpkg -l | grep linux-image (Ubuntu/Debian) or rpm -qa | grep kernel (RHEL/CentOS)

FAQ

What is CVE-2024-39503?

CVE-2024-39503 is a race condition in the Linux kernel's netfilter ipset subsystem where garbage collection of list:set types can access memory after it has been freed during namespace cleanup, potentially causing kernel crashes or memory corruption.

Is CVE-2024-39503 being actively exploited?

No, this vulnerability is not listed on CISA's Known Exploited Vulnerabilities (KEV) catalog and no public exploits are known. However, it requires local access and elevated privileges to trigger, making opportunistic exploitation less likely.

What versions of Kernel are affected by CVE-2024-39503?

Linux kernel versions 6.8.1 through 6.9.5 are affected. The vulnerability is resolved in kernel 6.9.6 and later.

How do I check if my server is vulnerable to CVE-2024-39503?

Run uname -r to check your kernel version; if it reports a version between 6.8.1 and 6.9.5 inclusive, your system is vulnerable. Additionally, verify ipset is in use with lsmod | grep ip_set.

Does Defensia detect CVE-2024-39503?

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-2024-39503 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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