[CVE-2026-98077][MODERATE REGULAR] netfilter: nf_conntrack_sip: fix OOB read in sip_skip_whitespace() [ Upstream

[CVE-2026-98077][MODERATE REGULAR] netfilter: nf_conntrack_sip: fix OOB read in sip_skip_whitespace() [ Upstream

[AL-KERNEL]

CVE: CVE-2026-98077
Priority: MODERATE REGULAR
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: netfilter: nf_conntrack_sip: fix OOB read in sip_skip_whitespace() [ Upstream
Commit: 60c012b2d05e1558b0f30ea3f15a2c3ca2f24d94
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=60c012b2d05e1558b0f30ea3f15a2c3ca2f24d94
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98077
Analysis date: Fri, 25 Sep 2026 13:25:04 -0400
ActionableScore: 0
ActionableScore lower bound: unknown
Actionable bucket: Ordinary Moderate
Manual review required: NO

Summary:
No one-sentence report phrase was found.

======================================================================
ABOUT THIS REPORT
======================================================================

The original Linux kernel CVE announcement for CVE-2026-98077 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98077

The original announcement does not normally provide a security severity
estimate, CVSS assessment, or enough information to determine whether the
reported kernel bug represents a practically relevant security issue.

This report was generated by AL-KERNEL, an AI-assisted Linux kernel
vulnerability analysis system developed by Alexander Larkin. It combines
an autonomous classifier with LLM-assisted technical analysis and a
separate ActionableScore mechanism.

The purpose of this report is to prioritize Linux kernel CVEs before
manual review, identify cases that require prompt investigation, and
support automatic closure of issues that are unlikely to have meaningful
security impact.

Published priority for this report: MODERATE REGULAR
Manual review required: NO

A detailed explanation of the methodology and priority rules is included
at the end of this message.

======================================================================
AL-KERNEL CLASSIFICATION RESULT
======================================================================

CVE-2026-98077	MODERATE	https://www.kernelcve.org/list/?q=CVE-2026-98077 CHECK WITH IMPACT FROM ORIG NN MODERATE	Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:H';CWE-125;*CWE-20;Other CVSS 'AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '6.5';DESCR 'An out of bounds read in the netfilter SIP connection tracking helper occurs because sip_skip_whitespace can return a pointer equal to the payload limit instead of NULL. A remote sender can reach the invalid read by supplying a recognized SIP header name followed only by spaces or tabs up to the exact end of the packet payload without a colon. For the CVSS the PR:N value is used because no account or local execution context is required when crafted SIP traffic can reach a system where the nf_conntrack_sip helper is active. The issue is network reachable but practical exposure depends on SIP connection tracking being loaded and assigned to the relevant traffic. The direct primitive is a one byte out of bounds read rather than memory corruption. Impact is normally limited to incorrect parsing or availability degradation, while an unfavorable buffer placement may cause a kernel fault and denial of service. There is no supported write primitive or credible privilege escalation path.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 0) 	MAYBE	REMOTE OOB NETFILTER  DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN4	-	-	checked

======================================================================
ACTIONABLESCORE ANALYSIS
======================================================================

ActionableScore=0
PrimitiveClass=CLASS_C
RealUAF=NO
HostAdminRequired=NO
NamespaceScopedPrivilege=UNKNOWN
ImportantCandidate=NO
ManualReview=RECOMMENDED
AutoDowngradeAllowed=YES

1. ActionableScore

* Raw conservative score: 0
* Conservative score: 0
* Raw paranoid score: 0
* Paranoid score: 0
* No floor or cap was applied.
* Final recommended bucket: **Ordinary Moderate**::

2. Signal breakdown

* +0 Limited one-byte OOB read. The pointer can equal the payload limit and is then dereferenced, but no write, UAF, disclosure path, or control-flow influence is established.
* +0 Remote reachability not awarded. Crafted traffic can trigger the read only where the SIP conntrack helper is loaded and assigned to that traffic, which is a material prior configuration prerequisite.
* +0 Reliable kernel crash not awarded. The commit establishes an invalid read but does not demonstrate an Oops or panic. The byte immediately after the logical payload can remain inside accessible skb backing storage.
* +0 Confidentiality not awarded. No byte read beyond the payload is copied to userspace or returned over the network.
* +0 Integrity and LPE not awarded. There is no write primitive, lifetime violation, controlled reclaim, or security-boundary bypass.
* +0 Extra availability not awarded. Incorrect parsing is possible, but host-wide failure or another strong availability consequence is not established.
* No negative points were applied. The score is low because the established primitive has limited security leverage, not because of assumed privilege, rarity, or difficult timing.

3. Reachability analysis

A remote sender can construct a recognized SIP header followed by spaces or tabs through the exact end of the payload. No account or local execution is required once packets are processed by the vulnerable helper, so HostAdminRequired is NO for the attacker.

The complete path nevertheless depends on nf_conntrack_sip being loaded and assigned to the relevant SIP traffic. That normally represents prior system configuration rather than something the remote attacker can instantiate. The supplied evidence does not establish that the complete setup is attacker-creatable through a user or network namespace, so NamespaceScopedPrivilege is UNKNOWN.

No special hardware, race, or timing window is involved. Triggering the logical over-read is deterministic for an exposed affected helper, but a production kernel fault is not established.

4. Primitive and severity interpretation

The exact primitive is a one-byte read at dptr equal to limit. This is a bounded invalid read, not a UAF, overwrite, stale structured-object use, repeated release, or ownership violation.

PrimitiveClass is CLASS_C because the demonstrated behavior is invalid parser access without an independently useful corruption primitive. No disclosure channel or meaningful behavior based on the byte value is shown. The likely production consequence is malformed SIP header rejection or parser inconsistency. A diagnostic KASAN report is plausible, while a kernel crash would require additional memory-layout circumstances not established here.

ImportantCandidate is NO because there is no Class A or unresolved Class B primitive. AutoDowngradeAllowed is YES because no meaningful corruption, lifetime, disclosure, authorization, or privilege-escalation leverage remains unresolved.

5. One-sentence report phrase

A remotely supplied truncated SIP header can cause a one-byte out-of-bounds read in nf_conntrack_sip when the helper is active, but no disclosure, write primitive, reliable kernel crash, or privilege-escalation path is established.

6. Manual review recommendation

MANUAL CHECK RECOMMENDED

Confirm product-specific nf_conntrack_sip activation and whether sanitizers or architecture-specific buffer placement turn the logical over-read into a reproducible kernel fault.

7. Call-site confidence

Call-site confidence: high

======================================================================
UPSTREAM PATCH SUMMARY
======================================================================

Patch: netfilter: nf_conntrack_sip: fix OOB read in sip_skip_whitespace() [ Upstream
Commit: 60c012b2d05e1558b0f30ea3f15a2c3ca2f24d94
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=60c012b2d05e1558b0f30ea3f15a2c3ca2f24d94

Changed files:
  net/netfilter/nf_conntrack_sip.c

Diff excerpt:

Not included in this email. See the upstream URL for the full patch.

Full patch:
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=60c012b2d05e1558b0f30ea3f15a2c3ca2f24d94

======================================================================
DETAILED REPORT METHODOLOGY
======================================================================

The original Linux kernel CVE announcement for CVE-2026-98077 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98077

The original CVE announcement normally does not include a security-level
estimate. In particular, it may not contain a CVSS assessment, an impact
level, or enough information to determine whether the reported bug is a
practically relevant security issue. One purpose of this parallel CVE list
is to provide that missing technical and prioritization information.

The original goal of the AL-KERNEL project was to prioritize Linux kernel
CVE analysis automatically before manual review. The system can also help
identify non-security issues that may be suitable for automatic closure.

This report was generated by AL-KERNEL, an AI-assisted Linux kernel
vulnerability analysis system developed by Alexander Larkin.

The first analysis stage combines an autonomous classifier with additional
LLM-based analysis. The autonomous classifier runs locally on a CPU and is
based on a backpropagation neural network. Together, these mechanisms
produce a technical vulnerability description, identify likely weakness
types, estimate CVSS severity, and provide input for ActionableScore.

Two CVSS estimates are retained because incomplete kernel vulnerability
information often permits more than one defensible interpretation:

  Conservative CVSS vector: AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
  The Best / paranoid CVSS vector: AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:H
  The Best / paranoid CVSS score: 6.5

The conservative vector represents a lower-impact interpretation.
The Best/paranoid vector intentionally represents a plausible upper-bound
interpretation and should not automatically be treated as demonstrated
real-world impact.

CVSS may also need to be adjusted for a particular Linux deployment,
because actual reachability, privileges, enabled kernel configuration,
hardware, namespaces, exposed device nodes, and other environmental
conditions can differ significantly between systems.

A separate ActionableScore mechanism evaluates practical remediation
urgency. Its analysis may include reachability, attack prerequisites,
subsystem exposure, memory-corruption characteristics, denial-of-service
reliability, and possible confidentiality, integrity, or
privilege-escalation impact.

  Conservative ActionableScore: unknown
  Paranoid ActionableScore: 0

The final base severity is taken directly from the second tab-separated
field of the AL-KERNEL classification result. ActionableScore does not
replace or independently override that final AL-KERNEL decision, and
if ActionableScore adjusted impact level of ALKERNEL, then you would see
self-readable flags above like INCREASED_TO_HIGH_BASED_ON_ACTIONABLESCOREHIGHEREQTHAN7.

For an AL-KERNEL result of MODERATE, this report uses the following
additional presentation split:

  ActionableScore below 5   -> MODERATE REGULAR
  ActionableScore 5 or more -> MODERATE 7.0

The distinction between MODERATE REGULAR and MODERATE 7.0 makes it
possible to identify Moderate issues that should receive manual analysis
and fixes before lower-priority MODERATE REGULAR issues. In many cases,
MODERATE REGULAR fixes may wait for a later rebase or routine update.

There is one override in which MODERATE REGULAR becomes MODERATE 7.0
even when the ActionableScore is below 5. When the AL-KERNEL result
contains the KPANIC flag, a MODERATE result is always presented as
MODERATE 7.0. The KPANIC flag selected with few regexps without
usage of AI at all, so it helps to detect cases when Kernel Crash happens
and similar (to filter False-Negative results from the LLM usage).

KPANIC indicates that a reliable kernel crash, kernel panic, or similarly
serious kernel availability impact was identified by the classification
workflow.

AL-KERNEL base severity for this report: MODERATE
KPANIC detected for this report: NO
Published priority for this report (same as in Subject): MODERATE REGULAR

These results are intended to support engineering triage. They are
machine-generated estimates, and cases marked for manual review should
be validated by a human security engineer before final disposition.
For more info read docs linked from here: https://kernelcve.org/
(and you can submit you own patch there to generate such a report
for non-existant CVE-id yet).

Note that in many cases this AI tool selects higher severity, than
real is (means you can expect Importants instead of Moderate 7.0 or
Moderates 7.0 instead of regular Moderates). If you see such cases,
please use reply email interface to add additional manual analyses
info to this particular CVE.
And please, please, let me know when you see Lows instead of Importants
or Important instead of Low (because particular for such cases I
need to tune this AI tool to make it better for this one and next similar).
My contact email for such notifications is alexanjelausa@gmail.com (and both
send reply to CVE record itself too and see "reply" button below for howto reply).