Full vulnerability report · 2026

CVE-2026-23011High confidence

ipv4: ip_gre: make ipgre_header() robust

Linux · Linux

Official source article: Siemens SSA-019113 ↗. Check the applicable product and release in the original source.

5.5MediumCVSS 3.1

Recommended action

Patch only the product branches with a verified fix

Medium technical severity with no CISA KEV confirmation; remediate through the normal risk-based patch cycle unless local exposure raises the priority. Verified remediation exists for at least one product or source, but 25 structured product or package states remain unresolved. Apply remediation only to the exact product branch confirmed by its source.

Fix availability varies by product

Operational reassessment

Published severity in operational context

Open reassessment dashboard →

Published severityMediumOperational priority:Low, lowered one band.downgradedsince 8 Sep 2026

Evidence used

No CISA KEV confirmation is currently recorded.
Exploitation requires an existing local or physical foothold with privileges.
EPSS is 0.21% for the current model date.

Compensating controls

Validate the affected product branch and deploy the verified fixed release.
Restrict local access and enforce least privilege on affected hosts.
Monitor vendor guidance and exploitation sources for a material change.

Verification

Confirm that the asset runs Linux Linux and falls inside the recorded affected range.
Verify the installed build against the product-specific fixed version after deployment.
Validate exposure, authentication requirements and compensating controls in the actual environment.
Reopen this reassessment when CVSS, KEV, EPSS, exploit evidence or remediation changes.

Cross-source reconciliation

Remediation availability differs by product scope

Verified remediation exists for at least one product or source, but 25 structured product or package states remain unresolved. Apply remediation only to the exact product branch confirmed by its source.

Siemens ProductCERT: 5 affected or under-investigation product states without a fixed product state in the same current advisory
Canonical Ubuntu Security: 20 affected package states with no published fix

Distribution package intelligence

Release-specific package status

Debian, ubuntu findings are scoped to the named distribution, release and source package. An absent finding does not mean a package is unaffected.

24 package states

Package result overrides the generic status

BlackTree has verified remediation for at least one product or source, but the relevant distribution still reports no fixed package for 20 affected package states shown here. Treat those rows as affected with no fix until that distribution publishes a fixed version.

Repository candidate not checked

A published vendor fix does not prove that a matching update is enabled and installable on a particular asset. Confirm the local package candidate before scheduling remediation.

Distribution release	Source package	Vendor state	Fixed version	Evidence
Debian trixietrixie · source	`linux`	Vendor fix publishedDebian records a fixed source-package version for this release.	`6.12.69-1`	Debian Security Tracker ↗Source updated 6 Oct 2026
Debian bookwormbookworm · source	`linux`	Vendor fix publishedDebian records a fixed source-package version for this release.	`6.1.162-1`	Debian Security Tracker ↗Source updated 6 Oct 2026
Debian forkyforky · source	`linux`	Vendor fix publishedDebian records a fixed source-package version for this release.	`6.18.8-1`	Debian Security Tracker ↗Source updated 6 Oct 2026
Debian sidsid · source	`linux`	Vendor fix publishedDebian records a fixed source-package version for this release.	`6.18.8-1`	Debian Security Tracker ↗Source updated 6 Oct 2026
Ubuntu 24.04 LTSnoble · standard archive	`linux`	Affected, no fix publishedCanonical OVAL identifies this running kernel flavour as affected and does not publish a fixed package version in this definition.	`Not published in this feed`	Canonical Ubuntu Security ↗Source updated 6 Oct 2026
Ubuntu 24.04 LTSnoble · standard archive	`linux-aws`	Affected, no fix publishedCanonical OVAL identifies this running kernel flavour as affected and does not publish a fixed package version in this definition.	`Not published in this feed`	Canonical Ubuntu Security ↗Source updated 6 Oct 2026
Ubuntu 24.04 LTSnoble · standard archive	`linux-azure`	Affected, no fix publishedCanonical OVAL identifies this running kernel flavour as affected and does not publish a fixed package version in this definition.	`Not published in this feed`	Canonical Ubuntu Security ↗Source updated 6 Oct 2026
Ubuntu 24.04 LTSnoble · standard archive	`linux-azure-fde`	Affected, no fix publishedCanonical OVAL identifies this running kernel flavour as affected and does not publish a fixed package version in this definition.	`Not published in this feed`	Canonical Ubuntu Security ↗Source updated 6 Oct 2026
Ubuntu 24.04 LTSnoble · standard archive	`linux-azure-nvidia`	Affected, no fix publishedCanonical OVAL identifies this running kernel flavour as affected and does not publish a fixed package version in this definition.	`Not published in this feed`	Canonical Ubuntu Security ↗Source updated 6 Oct 2026
Ubuntu 24.04 LTSnoble · standard archive	`linux-gcp`	Affected, no fix publishedCanonical OVAL identifies this running kernel flavour as affected and does not publish a fixed package version in this definition.	`Not published in this feed`	Canonical Ubuntu Security ↗Source updated 6 Oct 2026
Ubuntu 24.04 LTSnoble · standard archive	`linux-gke`	Affected, no fix publishedCanonical OVAL identifies this running kernel flavour as affected and does not publish a fixed package version in this definition.	`Not published in this feed`	Canonical Ubuntu Security ↗Source updated 6 Oct 2026
Ubuntu 24.04 LTSnoble · standard archive	`linux-gkeop`	Affected, no fix publishedCanonical OVAL identifies this running kernel flavour as affected and does not publish a fixed package version in this definition.	`Not published in this feed`	Canonical Ubuntu Security ↗Source updated 6 Oct 2026
Ubuntu 24.04 LTSnoble · standard archive	`linux-ibm`	Affected, no fix publishedCanonical OVAL identifies this running kernel flavour as affected and does not publish a fixed package version in this definition.	`Not published in this feed`	Canonical Ubuntu Security ↗Source updated 6 Oct 2026
Ubuntu 24.04 LTSnoble · standard archive	`linux-lowlatency`	Affected, no fix publishedCanonical OVAL identifies this running kernel flavour as affected and does not publish a fixed package version in this definition.	`Not published in this feed`	Canonical Ubuntu Security ↗Source updated 6 Oct 2026
Ubuntu 24.04 LTSnoble · standard archive	`linux-nvidia`	Affected, no fix publishedCanonical OVAL identifies this running kernel flavour as affected and does not publish a fixed package version in this definition.	`Not published in this feed`	Canonical Ubuntu Security ↗Source updated 6 Oct 2026
Ubuntu 24.04 LTSnoble · standard archive	`linux-nvidia-lowlatency`	Affected, no fix publishedCanonical OVAL identifies this running kernel flavour as affected and does not publish a fixed package version in this definition.	`Not published in this feed`	Canonical Ubuntu Security ↗Source updated 6 Oct 2026
Ubuntu 24.04 LTSnoble · standard archive	`linux-nvidia-tegra`	Affected, no fix publishedCanonical OVAL identifies this running kernel flavour as affected and does not publish a fixed package version in this definition.	`Not published in this feed`	Canonical Ubuntu Security ↗Source updated 6 Oct 2026
Ubuntu 24.04 LTSnoble · standard archive	`linux-oem-6.11`	Affected, no fix publishedCanonical OVAL identifies this running kernel flavour as affected and does not publish a fixed package version in this definition.	`Not published in this feed`	Canonical Ubuntu Security ↗Source updated 6 Oct 2026
Ubuntu 24.04 LTSnoble · standard archive	`linux-oracle`	Affected, no fix publishedCanonical OVAL identifies this running kernel flavour as affected and does not publish a fixed package version in this definition.	`Not published in this feed`	Canonical Ubuntu Security ↗Source updated 6 Oct 2026
Ubuntu 24.04 LTSnoble · standard archive	`linux-raspi`	Affected, no fix publishedCanonical OVAL identifies this running kernel flavour as affected and does not publish a fixed package version in this definition.	`Not published in this feed`	Canonical Ubuntu Security ↗Source updated 6 Oct 2026
Ubuntu 24.04 LTSnoble · standard archive	`linux-raspi-realtime`	Affected, no fix publishedCanonical OVAL identifies this running kernel flavour as affected and does not publish a fixed package version in this definition.	`Not published in this feed`	Canonical Ubuntu Security ↗Source updated 6 Oct 2026
Ubuntu 24.04 LTSnoble · standard archive	`linux-realtime`	Affected, no fix publishedCanonical OVAL identifies this running kernel flavour as affected and does not publish a fixed package version in this definition.	`Not published in this feed`	Canonical Ubuntu Security ↗Source updated 6 Oct 2026
Ubuntu 24.04 LTSnoble · standard archive	`linux-riscv`	Affected, no fix publishedCanonical OVAL identifies this running kernel flavour as affected and does not publish a fixed package version in this definition.	`Not published in this feed`	Canonical Ubuntu Security ↗Source updated 6 Oct 2026
Ubuntu 24.04 LTSnoble · standard archive	`linux-xilinx`	Affected, no fix publishedCanonical OVAL identifies this running kernel flavour as affected and does not publish a fixed package version in this definition.	`Not published in this feed`	Canonical Ubuntu Security ↗Source updated 6 Oct 2026

Direct vendor intelligence

Authoritative vendor CSAF and VEX advisories

Structured product status and remediation from the issuing vendor. Product-state explanations are always visible; large lists can be searched or downloaded.

1 current

SSA-019113 · CSAF 2.0 · revision 2 · interimSiemens ProductCERTSSA-019113: Vulnerabilities in the additional GNU/Linux subsystem of the SIMATIC S7-1500 CPU 1518(F)-4 PN/DP MFP V3.1.6

5 known affected

The vendor explicitly identifies these products as affected by this CVE.

SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AB0) >= V3.1.6
SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AC0) >= V3.1.6
SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AB0) >= V3.1.6
SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AC0) >= V3.1.6
SIPLUS S7-1500 CPU 1518-4 PN/DP MFP (6AG1518-4AX00-4AC0) >= V3.1.6

Summary: In the Linux kernel, the following vulnerability has been resolved: ipv4: ip_gre: make ipgre_header() robust Analog to commit db5b4e39c4e6 ("ip6_gre: make ip6gre_header() robust") Over the years, syzbot found many ways to crash the kernel in ipgre_header() [1]. This involves team or bonding drivers ability to dynamically change their dev->needed_headroom and/or dev->hard_header_len In this particular crash mld_newpack() allocated an skb with a too small reserve/headroom, and by the time mld_sendpack() was called, syzbot managed to attach an ipgre device. [1] skbuff: skb_under_panic: text:ffffffff89ea3cb7 len:2030915468 put:2030915372 head:ffff888058b43000 data:ffff887fdfa6e194 tail:0x120 end:0x6c0 dev:team0 kernel BUG at net/core/skbuff.c:213 ! Oops: invalid opcode: 0000 [#1] SMP KASAN PTI CPU: 1 UID: 0 PID: 1322 Comm: kworker/1:9 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025 Workqueue: mld mld_ifc_work RIP: 0010:skb_panic+0x157/0x160 net/core/skbuff.c:213 Call Trace: skb_under_panic net/core/skbuff.c:223 [inline] skb_push+0xc3/0xe0 net/core/skbuff.c:2641 ipgre_header+0x67/0x290 net/ipv4/ip_gre.c:897 dev_hard_header include/linux/netdevice.h:3436 [inline] neigh_connected_output+0x286/0x460 net/core/neighbour.c:1618 NF_HOOK_COND include/linux/netfilter.h:307 [inline] ip6_output+0x340/0x550 net/ipv6/ip6_output.c:247 NF_HOOK+0x9e/0x380 include/linux/netfilter.h:318 mld_sendpack+0x8d4/0xe60 net/ipv6/mcast.c:1855 mld_send_cr net/ipv6/mcast.c:2154 [inline] mld_ifc_work+0x83e/0xd60 net/ipv6/mcast.c:2693 process_one_work kernel/workqueue.c:3257 [inline] process_scheduled_works+0xad1/0x1770 kernel/workqueue.c:3340 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3421 kthread+0x711/0x8a0 kernel/kthread.c:463 ret_from_fork+0x510/0xa50 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246
Remediation: Limit access to the interactive shell of the additional GNU/Linux subssytem to trusted personnel only.

Recommended actionPatch only the product branches with a verified fix

Fix availability varies by product

What, why and how

In the Linux kernel, the following vulnerability has been resolved: ipv4: ip_gre: make ipgre_header() robust Analog to commit db5b4e39c4e6 ("ip6_gre: make ip6gre_header() robust") Over the years, syzbot found many ways to crash the kernel in ipgre_header() [1]. This involves team or bonding drivers ability to dynamically change their dev->needed_headroom and/or dev->hard_header_len In this particular crash mld_newpack() allocated an skb with a too small reserve/headroom, and by the time mld_sendpack() was called, syzbot managed to attach an ipgre device. [1] skbuff: skb_under_panic: text:ffffffff89ea3cb7 len:2030915468 put:2030915372 head:ffff888058b43000 data:ffff887fdfa6e194 tail:0x120 end:0x6c0 dev:team0 kernel BUG at net/core/skbuff.c:213 ! Oops: invalid opcode: 0000 [#1] SMP KASAN PTI CPU: 1 UID: 0 PID: 1322 Comm: kworker/1:9 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025 Workqueue: mld mld_ifc_work RIP: 0010:skb_panic+0x157/0x160 net/core/skbuff.c:213 Call Trace: <TASK> skb_under_panic net/core/skbuff.c:223 [inline] skb_push+0xc3/0xe0 net/core/skbuff.c:2641 ipgre_header+0x67/0x290 net/ipv4/ip_gre.c:897 dev_hard_header include/linux/netdevice.h:3436 [inline] neigh_connected_output+0x286/0x460 net/core/neighbour.c:1618 NF_HOOK_COND include/linux/netfilter.h:307 [inline] ip6_output+0x340/0x550 net/ipv6/ip6_output.c:247 NF_HOOK+0x9e/0x380 include/linux/netfilter.h:318 mld_sendpack+0x8d4/0xe60 net/ipv6/mcast.c:1855 mld_send_cr net/ipv6/mcast.c:2154 [inline] mld_ifc_work+0x83e/0xd60 net/ipv6/mcast.c:2693 process_one_work kernel/workqueue.c:3257 [inline] process_scheduled_works+0xad1/0x1770 kernel/workqueue.c:3340 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3421 kthread+0x711/0x8a0 kernel/kthread.c:463 ret_from_fork+0x510/0xa50 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246

What

Why

The current structured CVE record identifies a security weakness, but the root cause requires confirmation in the linked vendor material.

How

An attacker operating through local access may attempt exploitation with low privileges. If successful, the issue may disrupt the affected service.

What

Why

The current structured CVE record identifies a security weakness, but the root cause requires confirmation in the linked vendor material.

How

An attacker operating through local access may attempt exploitation with low privileges. If successful, the issue may disrupt the affected service.

Exploit reality and attack path

CVSS severity, EPSS forecast probability, public exploit material and CISA-confirmed exploitation are separate signals.

Observed exploitation

Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.

No confirmed evidence

No CISA KEV match was present at the last successful refresh. This means no confirmation from that source, not proof of no exploitation.

Public PoC / exploit material

Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.

None recorded

No exploit-tagged reference or CISA SSVC proof-of-concept state is currently recorded. Research may still exist outside the structured feeds.

Likely attack path: local access → vulnerable operation → disrupt the affected service
Attack surface: Local
Privileges required: Low: a basic authenticated account is required
User interaction: None
Attack complexity: Low: no specialised conditions are recorded
Security boundary: Unchanged: impact remains within the vulnerable component's security authority
Weakness ? CWE means Common Weakness Enumeration.: CWE not yet assigned
CVSS vector ? CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity.: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Common Vulnerability Scoring System 3.1: the compact vector below is decoded into plain language.
AVLocalAttack vector: The attacker needs local access to the vulnerable system.ACLowAttack complexity: No specialised conditions are required beyond attacker-controlled input.PRLowPrivileges required: The attacker needs basic user-level privileges.UINoneUser interaction: No action by another user is required.SUnchangedScope: The security impact remains within the vulnerable component's authority.CNoneConfidentiality impact: No direct loss is represented by this metric.INoneIntegrity impact: No direct loss is represented by this metric.AHighAvailability impact: A successful attack can cause a major loss.
Post-exploitation / living off the land: The issue can support a local privilege or sandbox boundary transition; normal system utilities may then be available in the gained context.

Denial of service

Official authority intelligence

Only matched European and national findings are included. Language selectors and unavailable sources are omitted.

ENISA EUVD · EUVD-2026-4623Official EUVD mapping

Official EUVD record ↗

BSI · German · WID-SEC-2026-0215Linux Kernel: Mehrere Schwachstellen

Ein Angreifer kann mehrere Schwachstellen im Linux Kernel ausnutzen, um nicht näher spezifizierte Angriffe durchzuführen, die möglicherweise zu einer Denial-of-Service- Bedingung führen oder eine Speicherbeschädigung verursachen können.