CVE-2026-89565 (GCVE-0-2026-89565)
Vulnerability from cvelistv5
Published
2026-09-11 19:44
Modified
2026-10-19 08:48
Severity ?
Summary
In the Linux kernel, the following vulnerability has been resolved: ipip: fix skb leak in collect_md mode when metadata_dst allocation fails In collect_md mode ipip_tunnel_rcv() returns 0 without freeing the skb when ip_tun_rx_dst() fails to allocate the metadata_dst. ipip_rcv() and mplsip_rcv() are registered as xfrm_tunnel handlers, so tunnel4_rcv() and tunnelmpls4_rcv() read the zero return as "the packet has been consumed" and do not free it either. The skb is leaked. The other tunnel drivers all dispose of the packet at this point: ip6_tunnel.c jumps to its drop label, ip_gre.c and ip6_gre.c return PACKET_REJECT, which makes gre_rcv() free the skb. Only ipip returns 0. Jump to the existing drop label instead. It frees the skb and still returns 0, so the packet keeps being reported as consumed, which is what we want here: the outer header has already been pulled, and neither the remaining handlers nor an ICMP unreachable have any use for it. Triggering this needs an ipip or mplsip tunnel in collect_md mode and an atomic allocation failure, which is why it has gone unnoticed.
References
Impacted products
Vendor Product Version
Linux Linux Version: cfc7381b3002756b1dcada32979e942aa3126e31
Version: cfc7381b3002756b1dcada32979e942aa3126e31
Version: cfc7381b3002756b1dcada32979e942aa3126e31
Version: cfc7381b3002756b1dcada32979e942aa3126e31
Version: cfc7381b3002756b1dcada32979e942aa3126e31
Version: cfc7381b3002756b1dcada32979e942aa3126e31
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      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nipip: fix skb leak in collect_md mode when metadata_dst allocation fails\n\nIn collect_md mode ipip_tunnel_rcv() returns 0 without freeing the skb\nwhen ip_tun_rx_dst() fails to allocate the metadata_dst. ipip_rcv() and\nmplsip_rcv() are registered as xfrm_tunnel handlers, so tunnel4_rcv()\nand tunnelmpls4_rcv() read the zero return as \"the packet has been\nconsumed\" and do not free it either. The skb is leaked.\n\nThe other tunnel drivers all dispose of the packet at this point:\nip6_tunnel.c jumps to its drop label, ip_gre.c and ip6_gre.c return\nPACKET_REJECT, which makes gre_rcv() free the skb. Only ipip returns 0.\n\nJump to the existing drop label instead. It frees the skb and still\nreturns 0, so the packet keeps being reported as consumed, which is what\nwe want here: the outer header has already been pulled, and neither the\nremaining handlers nor an ICMP unreachable have any use for it.\n\nTriggering this needs an ipip or mplsip tunnel in collect_md mode and an\natomic allocation failure, which is why it has gone unnoticed."
        }
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      "providerMetadata": {
        "dateUpdated": "2026-10-19T08:48:58.760Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
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          "url": "https://git.kernel.org/stable/c/6776efe4a52f289a3fc18f8adf19b035a7d8e1bb"
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      "title": "ipip: fix skb leak in collect_md mode when metadata_dst allocation fails",
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    "datePublished": "2026-09-11T19:44:35.858Z",
    "dateReserved": "2026-09-11T19:38:34.725Z",
    "dateUpdated": "2026-10-19T08:48:58.760Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
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}


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