* [CVE-2026-80945][MODERATE 7.0] crypto: iaa - unmap dst before software fallback on decompress [ Upstream
@ 2026-09-11 21:13 21% AL-KERNEL
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From: AL-KERNEL @ 2026-09-11 21:13 UTC (permalink / raw)
To: kernel-cve
CVE: CVE-2026-80945
Priority: MODERATE 7.0
AL-KERNEL base severity: MODERATE
KPANIC flag: YES
Patch: crypto: iaa - unmap dst before software fallback on decompress [ Upstream
Commit: fc933a4a419ba8a75da28666a018602c44846953
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=fc933a4a419ba8a75da28666a018602c44846953
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80945
Analysis date: Fri, 11 Sep 2026 17:13:08 -0400
ActionableScore: 5
ActionableScore lower bound: 4
Actionable bucket: Actionable Moderate
Manual review required: YES
Summary:
No one-sentence report phrase was found.
======================================================================
ABOUT THIS REPORT
======================================================================
The original Linux kernel CVE announcement for CVE-2026-80945 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80945
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 7.0
Manual review required: YES
A detailed explanation of the methodology and priority rules is included
at the end of this message.
======================================================================
AL-KERNEL CLASSIFICATION RESULT
======================================================================
CVE-2026-80945 MODERATE https://www.kernelcve.org/list/?q=CVE-2026-80945 CHECK WITH IMPACT FROM ORIG NN LOW Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:H';CWE-662;*CWE-664;CWE-703;Other CVSS 'AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:L/A:L';BEST CVSS score: '5.8';DESCR 'A data corruption issue in the Intel IAA crypto decompression path occurs when the software fallback runs while req dst is still mapped DMA_FROM_DEVICE. With SWIOTLB enabled, dma_unmap_sg can later copy stale bounce buffer contents over the CPU written fallback output, corrupting the decompressed result. For the CVSS the PR:L is used because practical triggering requires a local user or local process able to drive a kernel crypto consumer that uses the deflate iaa decompressor. The issue is not directly network reachable from the patch context. Impact is primarily integrity loss of decompressed data and possible denial of service if corrupted output breaks a kernel consumer. For the paranoid score, the highest still defensible interpretation is C:L/I:L/A:H because stale DMA data may affect returned decompression output, but the patch does not show a UAF, OOB write, or arbitrary write primitive.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Actionable Moderate (with actual score 5) YES HARDWARE KPANIC MEMORY YES NO checked
======================================================================
ACTIONABLESCORE ANALYSIS
======================================================================
ActionableScore=5
ActionableScoreLower=4
PrimitiveClass=CLASS_B
RealUAF=NO
HostAdminRequired=UNKNOWN
NamespaceScopedPrivilege=NO
ImportantCandidate=NO
ManualReview=REQUIRED
AutoDowngradeAllowed=NO
1. ActionableScore
* Raw conservative score: 4
* Conservative score: 4
* Raw paranoid score: 5
* Paranoid score: 5
* Final recommended bucket: **Actionable Moderate**::
No floor or cap changed the conservative score. No floor or cap changed the paranoid score.
2. Signal breakdown
Positive signals:
* +1 Constrained kernel buffer overwrite. The stale SWIOTLB bounce buffer can be copied over req->dst during dma_unmap_sg(), corrupting the decompression result.
* +1 Active DMA ownership and synchronization violation. The software fallback writes req->dst with the CPU while the buffer is still mapped DMA_FROM_DEVICE, and the normal unmap ownership transition happens too late.
* +1 Integrity plausible. The decompressed output returned to the caller can be corrupted.
* +1 Practical chain to meaningful consequence. The patch-supported chain is hardware analytics error -> software fallback writes output -> later DMA unmap copies stale bounce data -> corrupted result.
Paranoid-only signal:
* +1 Consumer-dependent kernel impact unresolved. The corrupted decompression result is produced by a kernel crypto decompression path and may affect higher-level consumers, so manual review is needed to determine whether this remains simple data corruption or can cause stronger availability or integrity effects.
Non-awarded material signals:
* RealUAF not awarded. No use-after-free or stale post-lifetime object use is established.
* Strong corruption not awarded. No arbitrary write, controlled target selection, controlled reclaim, type confusion, callback control, or refcount takeover is shown.
* Confidentiality not awarded. The patch does not establish a read-back or disclosure path for stale SWIOTLB contents.
* Reliable kernel crash not awarded. Corrupted output could break a consumer, but a direct host-wide crash is not demonstrated.
* Remote reachability not awarded. The vulnerable path is not directly packet-triggered from the supplied evidence.
* Race penalty not applied. This is an ordered DMA ownership bug, not a narrow timing race.
* Hardware rarity penalty not applied in arithmetic. Intel IAA and SWIOTLB are material prerequisites, but the evidence does not justify treating the path as physical-only or unreachable enough to downgrade the primitive.
3. Reachability analysis
The trigger requires use of the Intel IAA deflate decompression path, a hardware analytics error that causes fallback to deflate-generic, and SWIOTLB behavior where a stale bounce buffer is copied back on DMA unmap.
The complete attacker privilege boundary is not fully established from the supplied patch. A local process may be able to influence decompression input if a kernel consumer exposes this crypto algorithm or if a configured subsystem uses IAA-backed decompression on attacker-controlled data. However, the supplied evidence does not prove ordinary unprivileged reachability end to end.
HostAdminRequired is UNKNOWN because the patch does not prove that host administrator privileges are required for the complete trigger, but it also does not prove that an ordinary local user can directly select and drive this exact IAA acomp path.
NamespaceScopedPrivilege is NO because no namespace-scoped capability path is involved or established.
No network trigger is established. Prior setup may include IAA hardware, driver availability, selected crypto consumer, and SWIOTLB active. No special race repeatability issue is present.
4. Primitive and severity interpretation
The exact primitive is DMA ownership misuse leading to stale bounce-buffer copyback over the intended decompression destination buffer.
This is not UAF and not arbitrary memory corruption. The target is the request destination buffer, not an attacker-selected kernel address. The payload is stale DMA bounce data, not a fully attacker-controlled overwrite payload from the patch alone.
PrimitiveClass is CLASS_B because a real kernel data corruption primitive exists in a DMA and crypto path, but exploitation leverage beyond corrupted decompression output remains unresolved.
Demonstrated consequence is corrupted decompression result. Speculative consequences include consumer-dependent DoS or broader integrity impact if a higher-level kernel user treats corrupted decompressed data as trusted state.
ImportantCandidate is NO because no controlled corruption, LPE, authorization bypass, disclosure, or strong exploitation primitive is established.
AutoDowngradeAllowed is NO because this is not a harmless warning or ordinary device-local failure. It is a concrete DMA/SWIOTLB result-corruption bug in a kernel crypto decompression path with consumer-dependent security impact requiring review.
Likely operational severity is Actionable Moderate.
5. One-sentence report phrase
A DMA synchronization bug in the Intel IAA decompression fallback can let stale SWIOTLB bounce-buffer data overwrite the CPU-generated software fallback output, causing corrupted decompression results and requiring manual review for consumer-dependent integrity or availability impact.
6. Manual review recommendation
MANUAL CHECK REQUIRED
Reason: the bug is a concrete DMA and SWIOTLB data corruption issue in a kernel crypto decompression path, and the security impact depends on which kernel consumers can feed and trust the corrupted decompression output.
7. Call-site confidence
Call-site confidence: medium
======================================================================
UPSTREAM PATCH SUMMARY
======================================================================
Patch: crypto: iaa - unmap dst before software fallback on decompress [ Upstream
Commit: fc933a4a419ba8a75da28666a018602c44846953
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=fc933a4a419ba8a75da28666a018602c44846953
Changed files:
drivers/crypto/intel/iaa/iaa_crypto_main.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=fc933a4a419ba8a75da28666a018602c44846953
======================================================================
DETAILED REPORT METHODOLOGY
======================================================================
The original Linux kernel CVE announcement for CVE-2026-80945 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80945
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:L/AC:H/PR:L/UI:N/S:U/C:N/I:L/A:L
The Best / paranoid CVSS vector: AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:H
The Best / paranoid CVSS score: 5.8
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: 4
Paranoid ActionableScore: 5
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: YES
Published priority for this report (same as in Subject): MODERATE 7.0
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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