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net: clear the dst when changing skb protocol

Type: advisorySource: Official CVE List1 source record

In 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.

Announced Source revision 1
Original source ↗

CVE-2025-38192

Primary source · Revision 1

Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.

Security context

Source reference: cve:CVE-2025-38192

Linux

Source reference: /containers/cna/affected/0/product

Affected versions
Not stated in this record
Fixed versions
Not stated in this record
Prerequisites
Not stated in this record

Linux

Source reference: /containers/cna/affected/1/product

Affected versions
Not stated in this record
Fixed versions
Not stated in this record
Prerequisites
Not stated in this record

Structured affected-version data

Original package identities and version rules from this source.

[
  {
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "vendor": "Linux",
    "product": "Linux",
    "versions": [
      {
        "status": "affected",
        "version": "6578171a7ff0c31dc73258f93da7407510abf085",
        "lessThan": "a046f183d21ab5ace5a96ece4cf9873a42f003a7",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "6578171a7ff0c31dc73258f93da7407510abf085",
        "lessThan": "98b1d8dc9a3170b2614f1e8c93854e75cdd83980",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "6578171a7ff0c31dc73258f93da7407510abf085",
        "lessThan": "bfa4d86e130a09f67607482e988313430e38f6c4",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "6578171a7ff0c31dc73258f93da7407510abf085",
        "lessThan": "2a3ad42a57b43145839f2f233fb562247658a6d9",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "6578171a7ff0c31dc73258f93da7407510abf085",
        "lessThan": "e9994e7b9f7bbb882d13c8191731649249150d21",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "6578171a7ff0c31dc73258f93da7407510abf085",
        "lessThan": "ba9db6f907ac02215e30128770f85fbd7db2fcf9",
        "versionType": "git"
      }
    ],
    "programFiles": [
      "net/core/filter.c"
    ],
    "defaultStatus": "unaffected"
  },
  {
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "vendor": "Linux",
    "product": "Linux",
    "versions": [
      {
        "status": "affected",
        "version": "4.8"
      },
      {
        "status": "unaffected",
        "version": "0",
        "lessThan": "4.8",
        "versionType": "semver"
      },
      {
        "status": "unaffected",
        "version": "5.15.209",
        "versionType": "semver",
        "lessThanOrEqual": "5.15.*"
      },
      {
        "status": "unaffected",
        "version": "6.1.167",
        "versionType": "semver",
        "lessThanOrEqual": "6.1.*"
      },
      {
        "status": "unaffected",
        "version": "6.6.95",
        "versionType": "semver",
        "lessThanOrEqual": "6.6.*"
      },
      {
        "status": "unaffected",
        "version": "6.12.35",
        "versionType": "semver",
        "lessThanOrEqual": "6.12.*"
      },
      {
        "status": "unaffected",
        "version": "6.15.4",
        "versionType": "semver",
        "lessThanOrEqual": "6.15.*"
      },
      {
        "status": "unaffected",
        "version": "6.16",
        "versionType": "original_commit_for_fix",
        "lessThanOrEqual": "*"
      }
    ],
    "programFiles": [
      "net/core/filter.c"
    ],
    "defaultStatus": "affected"
  }
]
Related CVEs
CVE-2025-38192

Source reference: /cveMetadata/cveId

Publisher severity

high

Source reference: /containers/cna/metrics

Event
#30537 · Revision 1
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Publisher date
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