high CVSS 7.5

CVE-2023-52340·Kernel vulnerability

The IPv6 implementation in the Linux kernel before 6.3 has a net/ipv6/route.c max_size threshold that can be consumed easily, e.g., leading to a denial of service (network is unreachable errors) when IPv6 packets are sent in a loop via a raw socket.

Severity
high
Software
Kernel
Fixed in
6.3
Published
2024-07-05

Affected versions

Until: 6.3

Fixed in: 6.3

How to fix this CVE

Update your Linux kernel to version 6.3 or later to patch the IPv6 routing table resource exhaustion vulnerability. This fix implements proper threshold management for IPv6 route cache entries, preventing attackers from consuming network resources through looped raw socket packets. Kernel updates should be applied promptly, followed by 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 your current kernel version with 'uname -r' and verify it is at least 6.3 or later
  2. Step 2: Verify IPv6 is enabled on your network interfaces using 'ip -6 addr show' to confirm potential exposure
  3. Step 3: Monitor dmesg and syslog for IPv6 routing errors with 'dmesg | grep -i ipv6' and 'journalctl -u kernel --grep ipv6'
  4. Step 4: Confirm the patch was applied by checking the kernel build timestamp: 'cat /proc/version' should show a version >= 6.3

FAQ

What is CVE-2023-52340?

CVE-2023-52340 is a denial-of-service vulnerability in the Linux kernel's IPv6 routing implementation where the route cache threshold can be exhausted through repeated IPv6 packets sent via raw sockets, causing network connectivity failures.

Is CVE-2023-52340 being actively exploited?

No, this vulnerability is not listed on the CISA KEV catalog and has no known public exploits, though it remains a moderate risk for availability-sensitive deployments.

What versions of Kernel are affected by CVE-2023-52340?

All Linux kernel versions prior to 6.3 are affected; kernel 6.3 and later include the remediation commit af6d10345ca76670c1b7c37799f0d5576ccef277.

How do I check if my server is vulnerable to CVE-2023-52340?

Run 'uname -r' to retrieve your kernel version—if it reports a version lower than 6.3, your system is vulnerable to this IPv6 routing DoS condition.

Does Defensia detect CVE-2023-52340?

Yes — Defensia's CVE advisory scanner compares installed package versions against the NVD database. If Kernel is installed on a monitored server, CVE-2023-52340 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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