GHSA-82XM-WM87-5FC2
Vulnerability from github – Published: 2025-07-04 15:31 – Updated: 2025-11-19 21:31In the Linux kernel, the following vulnerability has been resolved:
net: clear the dst when changing skb protocol
A not-so-careful NAT46 BPF program can crash the kernel if it indiscriminately flips ingress packets from v4 to v6:
BUG: kernel NULL pointer dereference, address: 0000000000000000 ip6_rcv_core (net/ipv6/ip6_input.c:190:20) ipv6_rcv (net/ipv6/ip6_input.c:306:8) process_backlog (net/core/dev.c:6186:4) napi_poll (net/core/dev.c:6906:9) net_rx_action (net/core/dev.c:7028:13) do_softirq (kernel/softirq.c:462:3) netif_rx (net/core/dev.c:5326:3) dev_loopback_xmit (net/core/dev.c:4015:2) ip_mc_finish_output (net/ipv4/ip_output.c:363:8) NF_HOOK (./include/linux/netfilter.h:314:9) ip_mc_output (net/ipv4/ip_output.c:400:5) dst_output (./include/net/dst.h:459:9) ip_local_out (net/ipv4/ip_output.c:130:9) ip_send_skb (net/ipv4/ip_output.c:1496:8) udp_send_skb (net/ipv4/udp.c:1040:8) udp_sendmsg (net/ipv4/udp.c:1328:10)
The output interface has a 4->6 program attached at ingress. We try to loop the multicast skb back to the sending socket. Ingress BPF runs as part of netif_rx(), pushes a valid v6 hdr and changes skb->protocol to v6. We enter ip6_rcv_core which tries to use skb_dst(). But the dst is still an IPv4 one left after IPv4 mcast output.
Clear the dst in all BPF helpers which change the protocol. Try to preserve metadata dsts, those may carry non-routing metadata.
{
"affected": [],
"aliases": [
"CVE-2025-38192"
],
"database_specific": {
"cwe_ids": [
"CWE-476"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2025-07-04T14:15:26Z",
"severity": "MODERATE"
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: clear the dst when changing skb protocol\n\nA not-so-careful NAT46 BPF program can crash the kernel\nif it indiscriminately flips ingress packets from v4 to v6:\n\n BUG: kernel NULL pointer dereference, address: 0000000000000000\n ip6_rcv_core (net/ipv6/ip6_input.c:190:20)\n ipv6_rcv (net/ipv6/ip6_input.c:306:8)\n process_backlog (net/core/dev.c:6186:4)\n napi_poll (net/core/dev.c:6906:9)\n net_rx_action (net/core/dev.c:7028:13)\n do_softirq (kernel/softirq.c:462:3)\n netif_rx (net/core/dev.c:5326:3)\n dev_loopback_xmit (net/core/dev.c:4015:2)\n ip_mc_finish_output (net/ipv4/ip_output.c:363:8)\n NF_HOOK (./include/linux/netfilter.h:314:9)\n ip_mc_output (net/ipv4/ip_output.c:400:5)\n dst_output (./include/net/dst.h:459:9)\n ip_local_out (net/ipv4/ip_output.c:130:9)\n ip_send_skb (net/ipv4/ip_output.c:1496:8)\n udp_send_skb (net/ipv4/udp.c:1040:8)\n udp_sendmsg (net/ipv4/udp.c:1328:10)\n\nThe output interface has a 4-\u003e6 program attached at ingress.\nWe try to loop the multicast skb back to the sending socket.\nIngress BPF runs as part of netif_rx(), pushes a valid v6 hdr\nand changes skb-\u003eprotocol to v6. We enter ip6_rcv_core which\ntries to use skb_dst(). But the dst is still an IPv4 one left\nafter IPv4 mcast output.\n\nClear the dst in all BPF helpers which change the protocol.\nTry to preserve metadata dsts, those may carry non-routing\nmetadata.",
"id": "GHSA-82xm-wm87-5fc2",
"modified": "2025-11-19T21:31:14Z",
"published": "2025-07-04T15:31:09Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2025-38192"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/2a3ad42a57b43145839f2f233fb562247658a6d9"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/ba9db6f907ac02215e30128770f85fbd7db2fcf9"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/bfa4d86e130a09f67607482e988313430e38f6c4"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/e9994e7b9f7bbb882d13c8191731649249150d21"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
"type": "CVSS_V3"
}
]
}
Sightings
| Author | Source | Type | Date |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.