CVE-2026-99041 (GCVE-0-2026-99041)

Vulnerability from cvelistv5 – Published: 2026-10-23 12:22 – Updated: 2026-10-30 12:41
VLAI
Title
ip6_gre: remove obsolete ERSPAN PMTU update
Summary
In the Linux kernel, the following vulnerability has been resolved: ip6_gre: remove obsolete ERSPAN PMTU update A tc tunnel_key action can attach a METADATA_IP_TUNNEL dst to an skb, and mirred can redirect it to a native ip6erspan device. The legacy PMTU update in ip6erspan_tunnel_xmit() treats that metadata dst as a route. Since it has no output device, dst_dev(dst)->mtu dereferences NULL. On v7.2 with KASAN, an initial UID/GID 65534 process with CapEff 0 used self-created user and network namespaces to trigger: KASAN: null-ptr-deref RIP: ip6erspan_tunnel_xmit+0x10fc/0x2cc0 Kernel panic - not syncing: Fatal exception in interrupt The update is obsolete. Commit fe1a4ca0a2b7 ("ip6_gre: process toobig in a better way") changed IPv6 GRE Too Big handling to update the underlay route and removed the equivalent block from __gre6_xmit(). ip6_tnl_xmit() then propagates the underlay PMTU to the overlay route. Remove the stale ERSPAN copy and its now-unused dst variable. This eliminates the metadata-dst dereference and keeps ERSPAN aligned with IPv6 GRE PMTU handling.
Severity
No CVSS data available.
Assigner
Linux CNA under the mitre root
CNA scorecard D 53/100 over 6643 records in the last 180 days details
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 5a963eb61b7c39e6c422b6e48619d19d04719358 , < 2e151c74bcc53e3ed313bd1c21b0d5bb442edbc0 (git)
Affected: 5a963eb61b7c39e6c422b6e48619d19d04719358 , < ba72ed1c8476ce68eb7152dfcbc5330cefcbaa91 (git)
Affected: 5a963eb61b7c39e6c422b6e48619d19d04719358 , < b14a682ad7d45345701e08f9279d483a1da8b36c (git)
Affected: 5a963eb61b7c39e6c422b6e48619d19d04719358 , < f5b143f4cd3fb7673df8d727550478a4b762908a (git)
Affected: 5a963eb61b7c39e6c422b6e48619d19d04719358 , < 2d06cb25a497d3a7034ef9d172626c2d6620a0f1 (git)
Affected: 5a963eb61b7c39e6c422b6e48619d19d04719358 , < 8f27260b989f488760289276377db24fbfb20bfa (git)
Affected: 5a963eb61b7c39e6c422b6e48619d19d04719358 , < 8bc60db48e8cba35488bbd6e1f94aa990afa275a (git)
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Linux Linux Affected: 4.16
Unaffected: 0 , < 4.16 (semver)
Unaffected: 5.15.224 , ≤ 5.15.* (semver)
Unaffected: 6.1.191 , ≤ 6.1.* (semver)
Unaffected: 6.6.160 , ≤ 6.6.* (semver)
Unaffected: 6.12.114 , ≤ 6.12.* (semver)
Unaffected: 6.18.58 , ≤ 6.18.* (semver)
Unaffected: 7.2.11 , ≤ 7.2.* (semver)
Unaffected: 7.3 , ≤ * (original_commit_for_fix)
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Show details on NVD website
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          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nip6_gre: remove obsolete ERSPAN PMTU update\n\nA tc tunnel_key action can attach a METADATA_IP_TUNNEL dst to an skb,\nand mirred can redirect it to a native ip6erspan device. The legacy PMTU\nupdate in ip6erspan_tunnel_xmit() treats that metadata dst as a route.\nSince it has no output device, dst_dev(dst)-\u003emtu dereferences NULL.\n\nOn v7.2 with KASAN, an initial UID/GID 65534 process with CapEff 0 used\nself-created user and network namespaces to trigger:\n\n  KASAN: null-ptr-deref\n  RIP: ip6erspan_tunnel_xmit+0x10fc/0x2cc0\n  Kernel panic - not syncing: Fatal exception in interrupt\n\nThe update is obsolete. Commit fe1a4ca0a2b7 (\"ip6_gre: process toobig\nin a better way\") changed IPv6 GRE Too Big handling to update the\nunderlay route and removed the equivalent block from __gre6_xmit().\nip6_tnl_xmit() then propagates the underlay PMTU to the overlay route.\n\nRemove the stale ERSPAN copy and its now-unused dst variable. This\neliminates the metadata-dst dereference and keeps ERSPAN aligned with\nIPv6 GRE PMTU handling."
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            "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nip6_gre: remove obsolete ERSPAN PMTU update\n\nA tc tunnel_key action can attach a METADATA_IP_TUNNEL dst to an skb,\nand mirred can redirect it to a native ip6erspan device. The legacy PMTU\nupdate in ip6erspan_tunnel_xmit() treats that metadata dst as a route.\nSince it has no output device, dst_dev(dst)-\u003emtu dereferences NULL.\n\nOn v7.2 with KASAN, an initial UID/GID 65534 process with CapEff 0 used\nself-created user and network namespaces to trigger:\n\n  KASAN: null-ptr-deref\n  RIP: ip6erspan_tunnel_xmit+0x10fc/0x2cc0\n  Kernel panic - not syncing: Fatal exception in interrupt\n\nThe update is obsolete. Commit fe1a4ca0a2b7 (\"ip6_gre: process toobig\nin a better way\") changed IPv6 GRE Too Big handling to update the\nunderlay route and removed the equivalent block from __gre6_xmit().\nip6_tnl_xmit() then propagates the underlay PMTU to the overlay route.\n\nRemove the stale ERSPAN copy and its now-unused dst variable. This\neliminates the metadata-dst dereference and keeps ERSPAN aligned with\nIPv6 GRE PMTU handling."
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      "cve": "CVE-2026-99041",
      "id": "CVE-2026-99041",
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      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2026-99041",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/2026/cve-2026-99041.json",
      "version": "4"
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  }
}



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