VulnerabilityPublished 23 Oct 2026

CVE-2026-99041: Linux kernel · ip6_gre: remove obsolete ERSPAN PMTU update

Source GCVE Database

Authoritative record:CVE-2026-99041· High

Not known to be exploited · fixed in f5b143f4cd3fb7673df8d727550478a4b762908a : patch Linux kernel soon.

Data as of 26 Oct 2026, 13:47 UTC

Severity

High

Rated by Threat Radar · CVSS not yet scored by NVD

EPSS: 0.1% chance of exploitation in 30 days – higher than 6% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in f5b143f4cd3fb7673df8d727550478a4b762908a, b14a682ad7d45345701e08f9279d483a1da8b36c, 8f27260b989f488760289276377db24fbfb20bfa +2

Exploitation evidence

Disclosed: evidence found.
CVE published 23 Oct 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

ghsa-p22x-mpcm-2h5h

What to do

Upgrade to a fixed release listed under Affected software.

Affected software

Product	Affected	Fixed in
LinuxLinux	Affected ≥ 5a963eb61b7c39e6c422b6e48619d19d04719358, < f5b143f4cd3fb7673df8d727550478a4b762908a	Fixed in f5b143f4cd3fb7673df8d727550478a4b762908a
LinuxLinux	Affected ≥ 5a963eb61b7c39e6c422b6e48619d19d04719358, < b14a682ad7d45345701e08f9279d483a1da8b36c	Fixed in b14a682ad7d45345701e08f9279d483a1da8b36c
LinuxLinux	Affected ≥ 5a963eb61b7c39e6c422b6e48619d19d04719358, < 8f27260b989f488760289276377db24fbfb20bfa	Fixed in 8f27260b989f488760289276377db24fbfb20bfa
LinuxLinux	Affected ≥ 5a963eb61b7c39e6c422b6e48619d19d04719358, < 8bc60db48e8cba35488bbd6e1f94aa990afa275a	Fixed in 8bc60db48e8cba35488bbd6e1f94aa990afa275a
LinuxLinux	Affected ≥ 5a963eb61b7c39e6c422b6e48619d19d04719358, < 2d06cb25a497d3a7034ef9d172626c2d6620a0f1	Fixed in 2d06cb25a497d3a7034ef9d172626c2d6620a0f1
LinuxLinux	Affected =4.16	Fixed in–

Description

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.

References

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