In the Linux kernel, the following vulnerability has been resolved:

netfilter: nf_nat_sip: reload possible stale data pointer

quoting sashiko:
 ------------------------------------------------------------------------
 [..] noticed a potential memory bug and header corruption involving the
 SIP NAT helper.

 In net/netfilter/nf_nat_sip.c:nf_nat_sip():
	if (skb_ensure_writable(skb, skb->len)) {
		nf_ct_helper_log(skb, ct, "cannot mangle packet");
		return NF_DROP;
	}
	uh = (void *)skb->data + protoff;
	uh->dest = ct_sip_info->forced_dport;
	if (!nf_nat_mangle_udp_packet(skb, ct, ctinfo, protoff,
				      0, 0, NULL, 0)) {

 If a cloned or fragmented SKB is reallocated by skb_ensure_writable(), the
 old data buffer is freed. However, nf_nat_sip() fails to update *dptr to
 point to the new buffer.

 It also appears to use nf_nat_mangle_udp_packet() on what could be a TCP
 packet, which would overwrite the sequence number with a checksum update.
 ------------------------------------------------------------------------

nf_conntrack_sip linerizes skbs, hence no fragmented skb can be seen.
But clones are possible, so rebuild dptr.

Disable nf_nat_mangle_udp_packet() branch for TCP streams.
It doesn't look like this can ever happen, else we should have received
bug reports about this, so just check the conntrack is UDP and drop
otherwise.

The calling conntrack_sip set ->forced_dport for SIP_HDR_VIA_UDP messages,
so I don't think this is ever expected to be true for a TCP stream.

https://git.kernel.org/stable/c/0e76e3e886cc9ee027337d5ad39cb96f57b7bdc7

https://git.kernel.org/stable/c/2bcf2c5052fb5e73e255140ab43f056aef409c27

https://git.kernel.org/stable/c/57e4e29644ec054d7021d296407e7ddd844afea2

https://git.kernel.org/stable/c/77e43bcb7ec177e293a5c3f1b91a2c5aebfb6c68

https://git.kernel.org/stable/c/bded21a4bf9bf86a79148be735723a97ca9a7532

https://git.kernel.org/stable/c/dc11f26685aa850f237226f0f463647aea58ab7c

https://git.kernel.org/stable/c/e38143c9b477f2968024c47c647dd4456a40aff1

https://git.kernel.org/stable/c/eae9c6ccb5af69c713a65f8ae219f5c1aa32cd17

[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","programFiles":["net/netfilter/nf_nat_sip.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","versions":[{"version":"7266507d89991fa1e989283e4e032c6d9357fe26","lessThan":"bded21a4bf9bf86a79148be735723a97ca9a7532","versionType":"git","status":"affected"},{"version":"7266507d89991fa1e989283e4e032c6d9357fe26","lessThan":"dc11f26685aa850f237226f0f463647aea58ab7c","versionType":"git","status":"affected"},{"version":"7266507d89991fa1e989283e4e032c6d9357fe26","lessThan":"e38143c9b477f2968024c47c647dd4456a40aff1","versionType":"git","status":"affected"},{"version":"7266507d89991fa1e989283e4e032c6d9357fe26","lessThan":"57e4e29644ec054d7021d296407e7ddd844afea2","versionType":"git","status":"affected"},{"version":"7266507d89991fa1e989283e4e032c6d9357fe26","lessThan":"eae9c6ccb5af69c713a65f8ae219f5c1aa32cd17","versionType":"git","status":"affected"},{"version":"7266507d89991fa1e989283e4e032c6d9357fe26","lessThan":"2bcf2c5052fb5e73e255140ab43f056aef409c27","versionType":"git","status":"affected"},{"version":"7266507d89991fa1e989283e4e032c6d9357fe26","lessThan":"0e76e3e886cc9ee027337d5ad39cb96f57b7bdc7","versionType":"git","status":"affected"},{"version":"7266507d89991fa1e989283e4e032c6d9357fe26","lessThan":"77e43bcb7ec177e293a5c3f1b91a2c5aebfb6c68","versionType":"git","status":"affected"}]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","programFiles":["net/netfilter/nf_nat_sip.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","versions":[{"version":"3.9","status":"affected"},{"version":"0","lessThan":"3.9","versionType":"semver","status":"unaffected"},{"version":"5.10.261","lessThanOrEqual":"5.10.*","versionType":"semver","status":"unaffected"},{"version":"5.15.212","lessThanOrEqual":"5.15.*","versionType":"semver","status":"unaffected"},{"version":"6.1.178","lessThanOrEqual":"6.1.*","versionType":"semver","status":"unaffected"},{"version":"6.6.145","lessThanOrEqual":"6.6.*","versionType":"semver","status":"unaffected"},{"version":"6.12.97","lessThanOrEqual":"6.12.*","versionType":"semver","status":"unaffected"},{"version":"6.18.40","lessThanOrEqual":"6.18.*","versionType":"semver","status":"unaffected"},{"version":"7.1.5","lessThanOrEqual":"7.1.*","versionType":"semver","status":"unaffected"},{"version":"7.2-rc3","lessThanOrEqual":"*","versionType":"original_commit_for_fix","status":"unaffected"}]}]