Openvswitch

CVE-2025-21958: Open vSwitch CT Labeling Bug in Linux Kernel
CVE-2025-21958 - April 01, 2025

In the Linux kernel, the following vulnerability has been resolved: Revert "openvswitch: switch to per-action label counting in conntrack" Currently, ovs_ct_set_labels() is only called for confirmed conntrack entries (ct) within ovs_ct_commit(). However, if the conntrack entry does not have the labels_ext extension, attempting to allocate it in ovs_ct_get_conn_labels() for a confirmed entry triggers a warning in nf_ct_ext_add(): WARN_ON(nf_ct_is_confirmed(ct)); This happens when the conntrack entry is created externally before OVS increments net->ct.labels_used. The issue has become more likely since commit fcb1aa5163b1 ("openvswitch: switch to per-action label counting in conntrack"), which changed to use per-action label counting and increment net->ct.labels_used when a flow with ct action is added. Since theres no straightforward way to fully resolve this issue at the moment, this reverts the commit to avoid breaking existing use cases.

Linux Kernel OVS tx lockup during netdev unregister
CVE-2025-21681 - January 31, 2025

In the Linux kernel, the following vulnerability has been resolved: openvswitch: fix lockup on tx to unregistering netdev with carrier Commit in a fixes tag attempted to fix the issue in the following sequence of calls: do_output -> ovs_vport_send -> dev_queue_xmit -> __dev_queue_xmit -> netdev_core_pick_tx -> skb_tx_hash When device is unregistering, the 'dev->real_num_tx_queues' goes to zero and the 'while (unlikely(hash >= qcount))' loop inside the 'skb_tx_hash' becomes infinite, locking up the core forever. But unfortunately, checking just the carrier status is not enough to fix the issue, because some devices may still be in unregistering state while reporting carrier status OK. One example of such device is a net/dummy. It sets carrier ON on start, but it doesn't implement .ndo_stop to set the carrier off. And it makes sense, because dummy doesn't really have a carrier. Therefore, while this device is unregistering, it's still easy to hit the infinite loop in the skb_tx_hash() from the OVS datapath. There might be other drivers that do the same, but dummy by itself is important for the OVS ecosystem, because it is frequently used as a packet sink for tcpdump while debugging OVS deployments. And when the issue is hit, the only way to recover is to reboot. Fix that by also checking if the device is running. The running state is handled by the net core during unregistering, so it covers unregistering case better, and we don't really need to send packets to devices that are not running anyway. While only checking the running state might be enough, the carrier check is preserved. The running and the carrier states seem disjoined throughout the code and different drivers. And other core functions like __dev_direct_xmit() check both before attempting to transmit a packet. So, it seems safer to check both flags in OVS as well.

Linux Kernel OpenVSwitch UAF in ovs_ct_exit
CVE-2024-27395 7.8 - High - May 14, 2024

In the Linux kernel, the following vulnerability has been resolved: net: openvswitch: Fix Use-After-Free in ovs_ct_exit Since kfree_rcu, which is called in the hlist_for_each_entry_rcu traversal of ovs_ct_limit_exit, is not part of the RCU read critical section, it is possible that the RCU grace period will pass during the traversal and the key will be free. To prevent this, it should be changed to hlist_for_each_entry_safe.

Dangling pointer

Open vSwitch: OOB stack read during IPv4 fragmentation
CVE-2021-46955 7.1 - High - February 27, 2024

In the Linux kernel, the following vulnerability has been resolved: openvswitch: fix stack OOB read while fragmenting IPv4 packets running openvswitch on kernels built with KASAN, it's possible to see the following splat while testing fragmentation of IPv4 packets: BUG: KASAN: stack-out-of-bounds in ip_do_fragment+0x1b03/0x1f60 Read of size 1 at addr ffff888112fc713c by task handler2/1367 CPU: 0 PID: 1367 Comm: handler2 Not tainted 5.12.0-rc6+ #418 Hardware name: Red Hat KVM, BIOS 1.11.1-4.module+el8.1.0+4066+0f1aadab 04/01/2014 Call Trace: dump_stack+0x92/0xc1 print_address_description.constprop.7+0x1a/0x150 kasan_report.cold.13+0x7f/0x111 ip_do_fragment+0x1b03/0x1f60 ovs_fragment+0x5bf/0x840 [openvswitch] do_execute_actions+0x1bd5/0x2400 [openvswitch] ovs_execute_actions+0xc8/0x3d0 [openvswitch] ovs_packet_cmd_execute+0xa39/0x1150 [openvswitch] genl_family_rcv_msg_doit.isra.15+0x227/0x2d0 genl_rcv_msg+0x287/0x490 netlink_rcv_skb+0x120/0x380 genl_rcv+0x24/0x40 netlink_unicast+0x439/0x630 netlink_sendmsg+0x719/0xbf0 sock_sendmsg+0xe2/0x110 ____sys_sendmsg+0x5ba/0x890 ___sys_sendmsg+0xe9/0x160 __sys_sendmsg+0xd3/0x170 do_syscall_64+0x33/0x40 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x7f957079db07 Code: c3 66 90 41 54 41 89 d4 55 48 89 f5 53 89 fb 48 83 ec 10 e8 eb ec ff ff 44 89 e2 48 89 ee 89 df 41 89 c0 b8 2e 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 35 44 89 c7 48 89 44 24 08 e8 24 ed ff ff 48 RSP: 002b:00007f956ce35a50 EFLAGS: 00000293 ORIG_RAX: 000000000000002e RAX: ffffffffffffffda RBX: 0000000000000019 RCX: 00007f957079db07 RDX: 0000000000000000 RSI: 00007f956ce35ae0 RDI: 0000000000000019 RBP: 00007f956ce35ae0 R08: 0000000000000000 R09: 00007f9558006730 R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000000000 R13: 00007f956ce37308 R14: 00007f956ce35f80 R15: 00007f956ce35ae0 The buggy address belongs to the page: page:00000000af2a1d93 refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x112fc7 flags: 0x17ffffc0000000() raw: 0017ffffc0000000 0000000000000000 dead000000000122 0000000000000000 raw: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000000 page dumped because: kasan: bad access detected addr ffff888112fc713c is located in stack of task handler2/1367 at offset 180 in frame: ovs_fragment+0x0/0x840 [openvswitch] this frame has 2 objects: [32, 144) 'ovs_dst' [192, 424) 'ovs_rt' Memory state around the buggy address: ffff888112fc7000: f3 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ffff888112fc7080: 00 f1 f1 f1 f1 00 00 00 00 00 00 00 00 00 00 00 >ffff888112fc7100: 00 00 00 f2 f2 f2 f2 f2 f2 00 00 00 00 00 00 00 ^ ffff888112fc7180: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ffff888112fc7200: 00 00 00 00 00 00 f2 f2 f2 00 00 00 00 00 00 00 for IPv4 packets, ovs_fragment() uses a temporary struct dst_entry. Then, in the following call graph: ip_do_fragment() ip_skb_dst_mtu() ip_dst_mtu_maybe_forward() ip_mtu_locked() the pointer to struct dst_entry is used as pointer to struct rtable: this turns the access to struct members like rt_mtu_locked into an OOB read in the stack. Fix this changing the temporary variable used for IPv4 packets in ovs_fragment(), similarly to what is done for IPv6 few lines below.

Out-of-bounds Read

Ovs Geneve Netlink Offload DoS/Memory Access via Crafted Packets
CVE-2023-3966 7.5 - High - February 22, 2024

A flaw was found in Open vSwitch where multiple versions are vulnerable to crafted Geneve packets, which may result in a denial of service and invalid memory accesses. Triggering this issue requires that hardware offloading via the netlink path is enabled.

Uncaught Exception

Open vSwitch 2.17.8 Memory Leak via xmalloc__ in lib/util.c
CVE-2024-22563 7.5 - High - January 19, 2024

openvswitch 2.17.8 was discovered to contain a memory leak via the function xmalloc__ in openvswitch-2.17.8/lib/util.c.

Memory Leak

A flaw was found in Open vSwitch that allows ICMPv6 Neighbor Advertisement packets between virtual machines to bypass OpenFlow rules
CVE-2023-5366 5.5 - Medium - October 06, 2023

A flaw was found in Open vSwitch that allows ICMPv6 Neighbor Advertisement packets between virtual machines to bypass OpenFlow rules. This issue may allow a local attacker to create specially crafted packets with a modified or spoofed target IP address field that can redirect ICMPv6 traffic to arbitrary IP addresses.

Insufficient Verification of Data Authenticity

An out-of-bounds read in Organization Specific TLV was found in various versions of OpenvSwitch.
CVE-2022-4337 9.8 - Critical - January 10, 2023

An out-of-bounds read in Organization Specific TLV was found in various versions of OpenvSwitch.

Out-of-bounds Read

An integer underflow in Organization Specific TLV was found in various versions of OpenvSwitch.
CVE-2022-4338 9.8 - Critical - January 10, 2023

An integer underflow in Organization Specific TLV was found in various versions of OpenvSwitch.

Out-of-bounds Read

The TSS (Tuple Space Search) algorithm in Open vSwitch 2.x through 2.17.2 and 3.0.0 allows remote attackers to cause a denial of service (delays of legitimate traffic) via crafted packet data
CVE-2019-25076 5.8 - Medium - September 08, 2022

The TSS (Tuple Space Search) algorithm in Open vSwitch 2.x through 2.17.2 and 3.0.0 allows remote attackers to cause a denial of service (delays of legitimate traffic) via crafted packet data that requires excessive evaluation time within the packet classification algorithm for the MegaFlow cache, aka a Tuple Space Explosion (TSE) attack.

A flaw was found in dpdk
CVE-2022-0669 6.5 - Medium - August 29, 2022

A flaw was found in dpdk. This flaw allows a malicious vhost-user master to attach an unexpected number of fds as ancillary data to VHOST_USER_GET_INFLIGHT_FD / VHOST_USER_SET_INFLIGHT_FD messages that are not closed by the vhost-user slave. By sending such messages continuously, the vhost-user master exhausts available fd in the vhost-user slave process, leading to a denial of service.

A memory leak was found in Open vSwitch (OVS) during userspace IP fragmentation processing
CVE-2021-3905 7.5 - High - August 23, 2022

A memory leak was found in Open vSwitch (OVS) during userspace IP fragmentation processing. An attacker could use this flaw to potentially exhaust available memory by keeping sending packet fragments.

Memory Leak

Open vSwitch (aka openvswitch) 2.11.0 through 2.15.0 has a use-after-free in decode_NXAST_RAW_ENCAP (called
CVE-2021-36980 5.5 - Medium - July 20, 2021

Open vSwitch (aka openvswitch) 2.11.0 through 2.15.0 has a use-after-free in decode_NXAST_RAW_ENCAP (called from ofpact_decode and ofpacts_decode) during the decoding of a RAW_ENCAP action.

Dangling pointer

A flaw was found in multiple versions of OpenvSwitch
CVE-2020-27827 7.5 - High - March 18, 2021

A flaw was found in multiple versions of OpenvSwitch. Specially crafted LLDP packets can cause memory to be lost when allocating data to handle specific optional TLVs, potentially causing a denial of service. The highest threat from this vulnerability is to system availability.

Resource Exhaustion

A vulnerability was found in openvswitch
CVE-2020-35498 7.5 - High - February 11, 2021

A vulnerability was found in openvswitch. A limitation in the implementation of userspace packet parsing can allow a malicious user to send a specially crafted packet causing the resulting megaflow in the kernel to be too wide, potentially causing a denial of service. The highest threat from this vulnerability is to system availability.

Resource Exhaustion

An issue was discovered in Open vSwitch (OvS) 2.7.x through 2.7.6
CVE-2018-17206 4.9 - Medium - September 19, 2018

An issue was discovered in Open vSwitch (OvS) 2.7.x through 2.7.6. The decode_bundle function inside lib/ofp-actions.c is affected by a buffer over-read issue during BUNDLE action decoding.

Out-of-bounds Read

An issue was discovered in Open vSwitch (OvS) 2.7.x through 2.7.6, affecting ofproto_rule_insert__ in ofproto/ofproto.c
CVE-2018-17205 7.5 - High - September 19, 2018

An issue was discovered in Open vSwitch (OvS) 2.7.x through 2.7.6, affecting ofproto_rule_insert__ in ofproto/ofproto.c. During bundle commit, flows that are added in a bundle are applied to ofproto in order. If a flow cannot be added (e.g., the flow action is a go-to for a group id that does not exist), OvS tries to revert back all previous flows that were successfully applied from the same bundle. This is possible since OvS maintains list of old flows that were replaced by flows from the bundle. While reinserting old flows, OvS has an assertion failure due to a check on rule state != RULE_INITIALIZED. This would work for new flows, but for an old flow the rule state is RULE_REMOVED. The assertion failure causes an OvS crash.

assertion failure

An issue was discovered in Open vSwitch (OvS) 2.7.x through 2.7.6, affecting parse_group_prop_ntr_selection_method in lib/ofp-util.c
CVE-2018-17204 4.3 - Medium - September 19, 2018

An issue was discovered in Open vSwitch (OvS) 2.7.x through 2.7.6, affecting parse_group_prop_ntr_selection_method in lib/ofp-util.c. When decoding a group mod, it validates the group type and command after the whole group mod has been decoded. The OF1.5 decoder, however, tries to use the type and command earlier, when it might still be invalid. This causes an assertion failure (via OVS_NOT_REACHED). ovs-vswitchd does not enable support for OpenFlow 1.5 by default.

assertion failure

In Open vSwitch (OvS) 2.7.0, while parsing an OFPT_QUEUE_GET_CONFIG_REPLY type OFP 1.0 message, there is a buffer over-read
CVE-2017-9214 9.8 - Critical - May 23, 2017

In Open vSwitch (OvS) 2.7.0, while parsing an OFPT_QUEUE_GET_CONFIG_REPLY type OFP 1.0 message, there is a buffer over-read that is caused by an unsigned integer underflow in the function `ofputil_pull_queue_get_config_reply10` in `lib/ofp-util.c`.

Integer underflow