* [CVE-2026-90213][LOW] firewire: core: fix memory leak in error path of build_tree() [ Upstream
@ 2026-09-18 9:50 21% AL-KERNEL
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From: AL-KERNEL @ 2026-09-18 9:50 UTC (permalink / raw)
To: kernel-cve
CVE: CVE-2026-90213
Priority: LOW
AL-KERNEL base severity: LOW
KPANIC flag: NO
Patch: firewire: core: fix memory leak in error path of build_tree() [ Upstream
Commit: 848eaef4d30b385eb074214b7fa58287506158ad
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=848eaef4d30b385eb074214b7fa58287506158ad
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-90213
Analysis date: Fri, 18 Sep 2026 05:50:18 -0400
ActionableScore: 1
ActionableScore lower bound: 0
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-2026-90213 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-90213
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: LOW
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-2026-90213 LOW https://www.kernelcve.org/list/?q=CVE-2026-90213 CHECK WITH IMPACT FROM ORIG NN LOW Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:P/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H';*CWE-401;*CWE-772;**CWE-400;Other CVSS 'AV:P/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '4.6';DESCR 'A memory leak in the FireWire topology build path can occur when build_tree detects invalid self ID topology data and returns from an error path after allocating fw_node objects. A malformed or malicious FireWire device could cause invalid topology information during bus reset and leave allocated node objects unreleased. For the CVSS the PR:N is used because the external trigger can be a device on the FireWire bus rather than a local user account on the target. The issue is not network reachable and requires physical access to the FireWire bus or control of an already attached FireWire device. Impact is denial of service through memory resource exhaustion only. No UAF, OOB write, arbitrary write, or information leak primitive is indicated by the code change.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 1) YES OOB LEAK ERRORPATH LINUS NO NO checked
======================================================================
ACTIONABLESCORE ANALYSIS
======================================================================
ActionableScore=1
ActionableScoreLower=0
PrimitiveClass=NONE
RealUAF=NO
HostAdminRequired=NO
NamespaceScopedPrivilege=NO
ImportantCandidate=NO
ManualReview=NO
AutoDowngradeAllowed=YES
1. ActionableScore
* Raw conservative score: 0
* Conservative score: 0
* Raw paranoid score: 1
* Paranoid score: 1
* Final recommended bucket: **Ordinary Moderate**::
No floor or cap was applied. Scores differ because the paranoid view counts realistic sustained accumulation from repeated invalid FireWire topology events, while the conservative view only counts the concrete leak and physical access limitation.
2. Signal breakdown
Conservative signals:
* +1 Concrete persistent kernel resource/reference leak. Allocated `fw_node` objects can remain unreleased on `build_tree()` error paths.
* +1 Firmware/device-mediated external influence. Invalid FireWire self ID topology data can be supplied by a malformed or malicious device on the bus.
* -2 Physical-only/uncommon hardware access. Practical triggering requires access to or control of a FireWire bus/device, not ordinary local or network reachability.
Paranoid additional signal:
* +1 Sustained resource exhaustion plausibility. Repeated bus resets with invalid topology data could accumulate leaked `fw_node` allocations and eventually cause memory-pressure DoS.
Important non-awarded signals:
* RealUAF not awarded. The patch fixes missing cleanup, not stale post-free use.
* Controlled reclaim not demonstrated.
* Arbitrary write not demonstrated.
* Confidentiality and integrity impact not awarded.
* Reliable immediate kernel crash not demonstrated.
* Remote network reachability not established.
* No concrete repeated release/refcount mutation exists.
* No security-boundary or authorization bypass exists.
3. Reachability analysis
The likely attacker is a physically present or already attached malformed FireWire device that can influence self ID topology data during bus reset. The issue is not reachable over IP networking and does not involve namespaces. No local host-admin operation is required by the attacker if the malicious device is already connected or physically attached, but physical FireWire access is a strong practical limitation. The trigger depends on FireWire hardware and topology reset behavior. There is no race requirement.
4. Primitive and severity interpretation
The exact primitive is a memory/resource leak of allocated `fw_node` objects on error paths in `build_tree()`. This is not an active structured UAF and not fixed stale storage. It is a missing release of allocated objects before returning `NULL`.
PrimitiveClass is `NONE` because the patch establishes no memory corruption, no UAF, no OOB access, no double free, no authorization bypass, and no ownership violation. The demonstrated consequence is resource leakage. The speculative consequence is memory exhaustion after repeated malformed topology events. There is no exploitation leverage beyond DoS.
ImportantCandidate is `NO` because this is a pure resource leak with physical/device-mediated reachability and no corruption primitive. AutoDowngradeAllowed is `YES` because no unresolved kernel corruption or security-boundary primitive remains.
5. One-sentence report phrase
A malformed FireWire topology self ID sequence can cause `build_tree()` to return through error paths without freeing allocated `fw_node` objects, leading to a physical device mediated memory leak and possible resource exhaustion DoS.
6. Manual review recommendation
NO MANUAL CHECK NEEDED
Reason: this is a physical/device-mediated memory leak with no UAF, no memory corruption, no authorization bypass, and no demonstrated confidentiality or integrity impact.
7. Call-site confidence
Call-site confidence: high
======================================================================
UPSTREAM PATCH SUMMARY
======================================================================
Patch: firewire: core: fix memory leak in error path of build_tree() [ Upstream
Commit: 848eaef4d30b385eb074214b7fa58287506158ad
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=848eaef4d30b385eb074214b7fa58287506158ad
Changed files:
drivers/firewire/core-topology.c
drivers/firewire/node-tree-test.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=848eaef4d30b385eb074214b7fa58287506158ad
======================================================================
DETAILED REPORT METHODOLOGY
======================================================================
The original Linux kernel CVE announcement for CVE-2026-90213 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-90213
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:P/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
The Best / paranoid CVSS vector: AV:P/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
The Best / paranoid CVSS score: 4.6
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: 0
Paranoid ActionableScore: 1
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: LOW
KPANIC detected for this report: NO
Published priority for this report (same as in Subject): LOW
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 [email protected] (and both
send reply to CVE record itself too and see "reply" button below for howto reply).
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