CVE-2026-98532 ipv6: do not let ipv6_find_hdr() return an offset past the packet end
A use-after-free vulnerability in the Linux kernel's IPv6 header parsing allows local attackers to cause a denial of service or potentially execute code via crafted packets.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-98532?
CVE-2026-98532 is a high-severity use after free vulnerability in Linux, published on 18 Oct 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
ipv6: do not let ipv6_find_hdr() return an offset past the packet end
ipv6_find_hdr() walks the extension header chain, skipping each header by the length that header itself declares. ipv6_optlen() returns up to 2048, and the skip is never checked against skb->len, so the offset stored in *offset can point past the end of the packet.
openvswitch installs that offset as the transport header, and update_ipv6_checksum() then reads and writes the transport checksum field out of bounds:
BUG: KASAN: slab-use-after-free in inet_proto_csum_replace16+0x445/0x470 Read of size 2 at addr ffff88810b754b06 by task ovs_ipv6_oob/629 CPU: 4 UID: 1000 PID: 629 Comm: ovs_ipv6_oob Tainted: G N 7.3.0-rc3+ #348 Call Trace: inet_proto_csum_replace16+0x445/0x470 set_ipv6_addr+0x3dd/0x460 do_execute_actions+0x6a3d/0x7c40 ovs_execute_actions+0xfd/0x480 ovs_packet_cmd_execute+0xc38/0xf20 genl_rcv_msg+0x59e/0x870 netlink_rcv_skb+0x18b/0x450 genl_rcv+0x2d/0x40 netlink_unicast+0x6bc/0xa20
The buggy address belongs to the object at ffff88810b754980 which belongs to the cache skbuff_small_head of size 704 The buggy address is located 390 bytes inside of freed 704-byte region [ffff88810b754980, ffff88810b754c40)
Other callers use that offset too, so bound it here rather than in one caller.
Reject a header whose declared length does not fit in the packet. ipv6_find_hdr() already fails with -EBADMSG on a malformed chain, so this adds no new failure mode.
Which versions are affected by CVE-2026-98532?
How do I fix CVE-2026-98532?
Apply the vendor's patch.
Upgrade to the fixed version. These bugs are found with fuzzing and sanitisers and avoided by memory-safe languages. More about Use after free.
Is CVE-2026-98532 being exploited?
There is no known exploitation of CVE-2026-98532 in the wild and no public exploit code.
Sources
Also known as AZL-108915, BELL-CVE-2026-98532, DEBIAN-CVE-2026-98532, GHSA-75wf-hf48-gmfv, UBUNTU-CVE-2026-98532.