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CVE Record

CVE-2026-23083: fou: Don't allow 0 for FOU_ATTR_IPPROTO.

In the Linux kernel, the following vulnerability has been resolved: fou: Don't allow 0 for FOU_ATTR_IPPROTO. fou_udp_recv() has the same problem mentioned in the previous patch. If FOU_ATTR_IPPROTO is set to 0, skb is not freed by fou_udp_recv() nor "resubmit"-ted in ip_protocol_deliver_rcu(). Let's forbid 0 for FOU_ATTR_IPPROTO.

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysisunknown

Security readout for executives and security teams

Plain-English summary

CVE-2026-23083 is a Linux kernel flaw in Foo-over-UDP packet handling. A protocol value of 0 could leave a network packet buffer neither freed nor properly reprocessed. The public record does not provide CVSS, CWE, confirmed business impact, or evidence of active exploitation.

Executive priority

Treat this as a kernel maintenance and exposure-validation item, not an emergency based on current evidence. Raise priority for internet-facing or network-processing systems, infrastructure using UDP encapsulation, and any Siemens assets confirmed affected by the vendor advisory.

Technical view

The fix forbids FOU_ATTR_IPPROTO value 0. The source states fou_udp_recv() shared a prior problem where skb was not freed by fou_udp_recv() and not resubmitted in ip_protocol_deliver_rcu(). This indicates a kernel network buffer handling defect in FOU, with affected Linux kernel versions listed by the CVE record.

Likely exposure

Exposure is most likely on systems running affected Linux kernel versions with FOU functionality present or configured. The bundle lists Linux kernel versions and stable commits, plus a Siemens advisory reference, but it does not identify specific Siemens products or deployment conditions.

Exploitation context

The CVE is not marked KEV, and the provided sources do not state active exploitation or public exploit availability. The available description is patch-focused and does not describe attacker prerequisites, reachability, or practical exploitability.

Researcher notes

The record lacks CVSS, CWE, exploitability details, and precise operational impact. Analysis should stay close to the stated defect: accepting FOU_ATTR_IPPROTO=0 created an skb lifecycle failure. Do not assume remote code execution or confirmed denial of service without vendor evidence.

Mitigation direction

  • Update affected Linux kernels to versions containing the referenced stable fixes.
  • Review Siemens SSA-019113 if Siemens products are in scope.
  • Check vendor advisories for distribution-specific backports and package versions.
  • Prioritize systems using FOU, tunneling, or specialized network encapsulation features.

Validation and detection

  • Inventory Linux kernel versions across servers, appliances, and embedded systems.
  • Confirm whether FOU kernel functionality is enabled or configured.
  • Map installed kernels to vendor-fixed packages or referenced stable commits.
  • Check Siemens advisories only for products actually deployed in the environment.
Prepared
Confidence
medium
Sources
10

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.

ATT&CK lookup starting points

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CVE-2026-23083 mapping review

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Vulnerability profileCVE Program record
Severity
Unknown
CVSS
Not scored
Known Exploited
No
Published
Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

0CVSS vectors
3Timeline events
2ADP providers
9Source links

SSVC decision data

CISA-ADPCISA Coordinator
Timestamp
Version
2.0.3
Exploitation: noneAutomatable: noTechnical Impact: total

Vulnerability timeline

Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.

  1. CVE reservedCVE Program

    The CVE ID was reserved by the assigning CNA.

  2. CVE publishedCVE Program

    The CVE record was published.

  3. CVE updatedCVE Program

    The CVE record metadata indicates this as the latest update time.

ADP provider summaries

CISA-ADPCISA ADP Vulnrichment
other:ssvc
siemens-SADPADP container

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinux23461551c00628c3f3fe9cf837bf53cf8f212b63, 23461551c00628c3f3fe9cf837bf53cf8f212b63, 23461551c00628c3f3fe9cf837bf53cf8f212b63, 23461551c00628c3f3fe9cf837bf53cf8f212b63, 23461551c00628c3f3fe9cf837bf53cf8f212b63, 23461551c00628c3f3fe9cf837bf53cf8f212b63, 23461551c00628c3f3fe9cf837bf53cf8f212b63unaffected
LinuxLinux3.18, 0, 5.10.249, 5.15.199, 6.1.162, 6.6.122, 6.12.68, 6.18.8, 6.19affected
Weakness

CWE details

No CWE listed

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.