Security readout for executives and security teams
Plain-English summary
A Linux firewall component can mishandle packets waiting in a queue when a related connection-tracking template is removed. Under the local, low-privilege conditions reflected in the CVSS vector, this may threaten system confidentiality, integrity, and availability. Exploitation also appears to require specific netfilter features and lifecycle timing.
Executive priority
Treat this as a high-priority, configuration-dependent kernel update. Accelerate assessment for shared Linux hosts and appliances permitting untrusted local access. Avoid assuming safety from version strings alone; require vendor confirmation and evidence that the corrected kernel is running.
Technical view
xt_CT rules can reference connection-tracking templates backed by helper or timeout-policy objects. If those objects disappear while packets remain in NFQUEUE, the pending packets can retain unsafe references. The kernel fix drops queued packets when the template rule is removed. Zone and event-cache filters are unaffected because their values are copied.
Likely exposure
The clearest candidates are affected Linux kernels using xt_CT templates with NFQUEUE, particularly where helper modules or nfnetlink_cttimeout policies may be removed. Systems not using these features are less likely exposed. The supplied version data is ambiguous and commit-oriented, so confirm status through the relevant distribution or appliance vendor.
Exploitation context
The CVSS vector describes a local attack requiring low privileges, low complexity, and no user interaction, with potentially high confidentiality, integrity, and availability impact. The supplied record is not in KEV, and no supplied source reports active exploitation or a public exploit. That absence does not prove exploitation is impossible.
Researcher notes
The record supplies no CWE and does not explicitly characterize the memory-safety consequence. Its stated fault is the survival of queued packets after referenced helper or timeout-policy objects can disappear. Researchers should correlate vendor backports by commit identity and avoid inferring affected package versions solely from upstream numbering.
Mitigation direction
- Install a vendor kernel update containing the applicable referenced stable fix.
- Use distribution or appliance advisories to map the fix to packaged kernel versions.
- Consult vendor guidance for temporary mitigations; none are specified in the supplied sources.
- Prioritize affected shared systems where untrusted users can obtain local access.
Validation and detection
- Record each system's running kernel build and distribution package revision.
- Check vendor changelogs for CVE-2026-23391 or an applicable referenced commit.
- Inventory use of xt_CT templates, NFQUEUE, helpers, and nfnetlink_cttimeout policies.
- After updating and rebooting, verify the fixed kernel is actively running.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
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
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CVE-2026-23391 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- High
- CVSS
- 7.8 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
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.
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H1.85.9LinuxVulnerability scoring details
Base CVSS 3.1 score
7.8HighVector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Vulnerability timeline
Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.
- CVE reservedCVE Program
The CVE ID was reserved by the assigning CNA.
- CVE publishedCVE Program
The CVE record was published.
- CVE updatedCVE Program
The CVE record metadata indicates this as the latest update time.
ADP provider summaries
Source materials
- CVE List V5 sourceCVE List V5
- https://git.kernel.org/stable/c/55445134d42b84cb0a272e42c98d233ca65eca83CVE reference, Linux
- https://git.kernel.org/stable/c/cc57506dd66555899560b9c0f24e813f034e12ecCVE reference, Linux
- https://git.kernel.org/stable/c/d2d0bae0c9a2a17b6990a2966f5cdce0813d6256CVE reference, Linux
- https://git.kernel.org/stable/c/63b8097cea1923fe82cd598068d0796da8c015ecCVE reference, Linux
- https://git.kernel.org/stable/c/19a230dec6bb8928e3f96387f9085cf2c79bcef9CVE reference, Linux
- https://git.kernel.org/stable/c/cb549925875fa06dd155e49db4ac2c5044c30f9cCVE reference, Linux
- https://git.kernel.org/stable/c/777d02efe3d630cca4c1b63962cec17c57711325CVE reference, Linux
- https://git.kernel.org/stable/c/f62a218a946b19bb59abdd5361da85fa4606b96bCVE reference, Linux
- https://cert-portal.siemens.com/productcert/html/ssa-082556.htmlCVE reference, siemens-SADP
- https://cert-portal.siemens.com/productcert/html/ssa-019113.htmlCVE reference, siemens-SADP
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.