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TI-2026-79834 Aliases CVE-2026-99041GHSA-p22x-mpcm-2h5h

NULL pointer dereference in Linux kernel ip6erspan tunnel transmit

Priority LOW 22Published · Updated

Key facts

Attack vector
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Privileges required
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User interaction
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Attack complexity
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Impact type
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Confidentiality · integrity · availability
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Fix status
Partial Red Hat: 4 without a fix

No CVSS vector from any source. Fix status from CNA and Red Hat.

Summary

The Linux kernel from 4.16 is affected by a flaw in the IPv6 ERSPAN tunnel transmit path. The legacy PMTU update treats tunnel metadata as a route and dereferences a NULL output device, which crashes the kernel. A local user without privileges who can create user and network namespaces can trigger it.

Written with Claude Haiku 5.5 from the sources below · 2026-11-06

Description from the CNA

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RIP: ip6erspan_tunnel_xmit+0x10fc/0x2cc0 Kernel panic - not syncing: Fatal exception in interrupt The update is obsolete.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.

Why it matters now

EPSS 0.00173 6th percentileScored 2026-11-07
Fix Partial Linux (Linux): 5.15.224, 6.1.191, 6.6.160 +4Red Hat: 4 without a fix

SSVC decision points

Not available: CISA has not published SSVC decision points for this record.

Affected products

VendorProductAffected versionsFixed inStatusSource
LinuxLinux4.16 and later5.15.224, 6.1.191, 6.6.160, 6.12.114, 6.18.58, 7.2.11, 7.3Patch availableCNA
  • Linux VendorLinux Affected 4.16 and later Fixed in 5.15.224, 6.1.191, 6.6.160, 6.12.114, 6.18.58, 7.2.11, 7.3 Patch available CNA

CPE names Threatist (inferred) · 1

Inferred from how NVD named this product before; not given by a source.

CPEVersionsRoleVendor
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*——Linux
  • cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* Versions — — ·Linux

Remediation

Upgrade the Linux kernel to 5.15.224, 6.1.191, 6.6.160, 6.12.114, 6.18.58, 7.2.11 or 7.3. Red Hat Enterprise Linux 8, 9 and 10 and Red Hat OpenShift Container Platform 4 are affected, and Red Hat lists no fix available for them.

Written with Claude Haiku 5.5 from the sources below · 2026-11-06

  • Fix · CNA Linux (Linux) Fixed in 5.15.224, 6.1.191, 6.6.160, 6.12.114, 6.18.58, 7.2.11, 7.3

Vendor assessments

Red Hat

Red Hat rating: Moderate. Red Hat's page for this CVE →

ProductStatusPlan or fix
Red Hat Enterprise Linux 10AffectedNo fix yet: Fix deferred
Red Hat Enterprise Linux 8AffectedNo fix yet: Fix deferred
Red Hat Enterprise Linux 9AffectedNo fix yet: Fix deferred
Red Hat OpenShift Container Platform 4AffectedNo fix yet: Fix deferred
Not affected: 2 products
  • Red Hat Enterprise Linux 6
  • Red Hat Enterprise Linux 7

Timeline

  1. 2026-10-23 Threatist record created from CVE-2026-99041
  2. 2026-10-23 Alias added: GHSA-p22x-mpcm-2h5h
  3. 2026-10-29 Affected versions changed · Red Hat
  4. 2026-10-29 CVSS score added · Red Hat
  5. 2026-10-30 Fix available: Linux/Linux@2e151c74bcc53e3ed313bd1c21b0d5bb442edbc0, Linux/[email protected], Linux/[email protected] +1 · CNA
  6. 2026-10-30 2 new references · CNA

References

Other 7

  • TI-2025-26358 tls: fix handling of zero-length records on the rx_list KEVCVSS 3.1CRITICAL 9.8
  • TI-2026-38352 netfilter: bridge: make ebt_snat ARP rewrite writable KEVCVSS 3.1HIGH 8.8
  • TI-2021-02452 Incorrect authorization in Ubuntu linux kernel KEVCVSS 3.1HIGH 8.8
  • TI-2013-05264 The (1) get_user and (2) put_user API functions in the Linux kernel before 3.5.5 on the… KEVCVSS 3.1HIGH 8.8
  • TI-2022-00125 Integer overflow in kernel KEVCVSS 3.1HIGH 8.4
  • TI-2013-01864 The perf_swevent_init function in kernel/events/core.c in the Linux kernel before 3.8.9… KEVCVSS 3.1HIGH 8.4
See all 21741 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences