* [CVE-2026-80755][MODERATE 7.0] selinux: reject a permission value exceeding the class permission count [ Upstream
@ 2026-09-03 8:52 21% AL-KERNEL
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From: AL-KERNEL @ 2026-09-03 8:52 UTC (permalink / raw)
To: kernel-cve
CVE: CVE-2026-80755
Priority: MODERATE 7.0
AL-KERNEL base severity: MODERATE
KPANIC flag: YES
Patch: selinux: reject a permission value exceeding the class permission count [ Upstream
Commit: 6c2ab7c4549f4f2305848df834e784651dbf1676
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=6c2ab7c4549f4f2305848df834e784651dbf1676
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80755
Analysis date: Thu, 03 Sep 2026 04:52:07 -0400
ActionableScore: 7
ActionableScore lower bound: 4
Actionable bucket: Strong Important candidate / Actionable Moderate at minimum
Manual review required: YES
Summary:
A malformed SELinux policy can set a permission value beyond the class permission count, causing `security_get_permissions()` to write past an `nprim` sized heap allocation and potentially leading to kernel crash or privilege-relevant memory corruption.
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ABOUT THIS REPORT
======================================================================
The original Linux kernel CVE announcement for CVE-2026-80755 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80755
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-2026-80755 MODERATE https://www.kernelcve.org/list/?q=CVE-2026-80755 CHECK WITH IMPACT FROM ORIG NN IMPORTANT Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H';*CWE-787;CWE-129;*CWE-20;Other CVSS 'AV:L/AC:L/PR:H/UI:N/S:U/C:L/I:L/A:H';BEST CVSS score: '7';DESCR 'SELinux policy parsing did not reject a permission value that is greater than the permission count of the owning class or common block. security_get_permissions later allocates an nprim-sized array and writes to perms(value - 1), so a malformed policy image can drive a kernel heap out-of-bounds write. For the CVSS the PR:L is used for the paranoid score because some deployments may delegate policy loading to a reduced-privilege root, service account, or policy management component rather than a full system administrator. The issue is not directly network reachable and normally requires local access to a SELinux policy load path. Impact is at least denial of service via kernel memory corruption and in worst case may allow privilege escalation, so the issue should be reviewed manually.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Strong Important candidate / Actionable Moderate at minimum (with actual score 6) YES WRITE OOB SIMPLEFIX LINUS KPANIC DECREASED_TO_MODERATE7_BASED_ON_FALSEPOSCHECKOFKP NO NO guess
======================================================================
ACTIONABLESCORE ANALYSIS
======================================================================
ActionableScore=7
ActionableScoreLower=4
## 1. ActionableScore
* Conservative score: 4
* Paranoid score: 7
* Final recommended bucket: **Strong Important candidate / Actionable Moderate at minimum**::
## 2. Signal breakdown
Conservative signals:
* Memory corruption, Strong corruption primitive: +2
The patch explicitly describes an out-of-bounds heap write: `security_get_permissions()` writes `perms[value - 1]` into an `nprim` sized `kcalloc()` array.
* Weak LPE concern: +1
The primitive is a kernel heap OOB write, but the overwrite appears constrained by SELinux policy parsing structures and no arbitrary write or controlled reclaim is demonstrated.
* Reliable kernel crash / strong DoS: +1
A malformed policy can corrupt kernel heap memory and plausibly crash the kernel or SELinux policy query path.
* Broad/default/common subsystem: +1
SELinux is a common security subsystem on many enterprise Linux systems.
* Requires admin/root/CAP_* in typical deployments: -2
Loading or replacing SELinux policy normally requires administrative privilege or a privileged policy management path.
Conservative total: 4
Paranoid signals:
* Memory corruption, Strong corruption primitive: +2
This is a concrete heap OOB write, not just a warning or validation-only correctness issue.
* Weak LPE concern: +1
A kernel heap write in SELinux policy parsing may become privilege-relevant if a reduced-privilege policy management component can feed crafted policy data.
* Reliable kernel crash / strong DoS: +1
Heap corruption can realistically produce a system-wide crash.
* Confidentiality impact plausible: +1
In the worst defensible case, heap corruption in a security subsystem may influence kernel objects enough to expose sensitive state, although no direct leak is shown.
* Integrity impact plausible: +1
The primitive is a write past the bounds of a heap allocation and may corrupt adjacent kernel data.
* Broad/default/common subsystem: +1
SELinux is widely deployed in security-sensitive Linux environments.
* No full admin penalty in paranoid interpretation: 0
Some deployments may delegate SELinux policy handling to service accounts, reduced-capability root, automation, or policy management components, so PR:L is defensible for triage sensitivity.
Paranoid total: 7
## 3. Reachability analysis
The normal trigger requires supplying a malformed SELinux policy image where a permission value is larger than the permission count of the owning class or common block. In typical deployments, loading SELinux policy is restricted to root or a privileged policy loader, so the conservative interpretation is privileged local access.
Namespaces and containers generally do not make this reachable by ordinary unprivileged users because SELinux policy loading is host-level security administration. However, if a product exposes delegated policy management, a reduced-privilege service account, or automation that accepts policy input, the practical privilege requirement can drop to PR:L.
The path is not network reachable by itself. Any remote relevance would require a separate management service that accepts attacker-influenced SELinux policy content.
Call-site confidence: high. The commit explicitly states the downstream allocation and write site in `security_get_permissions()` and the patch directly bounds `perdatum->value` by `s->nprim`.
## 4. Severity interpretation
This should not be treated as an ordinary Moderate cleanup because the patch fixes a concrete kernel heap out-of-bounds write. The realistic exploitation evidence supports at least DoS and manual review. The stronger privilege-escalation case is not proven, but it is technically plausible enough for paranoid triage because the corruption occurs in kernel heap memory inside SELinux policy handling.
This is best handled as Actionable Moderate at minimum, with Strong Important candidate treatment when delegated or reduced-privilege policy loading exists.
## 5. One-sentence report phrase
A malformed SELinux policy can set a permission value beyond the class permission count, causing `security_get_permissions()` to write past an `nprim` sized heap allocation and potentially leading to kernel crash or privilege-relevant memory corruption.
## 6. Manual review recommendation
MANUAL CHECK REQUIRED
Reason: the patch fixes a concrete kernel heap out-of-bounds write in SELinux policy parsing, with plausible DoS and possible privilege-escalation impact depending on who can supply or load policy data.
======================================================================
UPSTREAM PATCH SUMMARY
======================================================================
Patch: selinux: reject a permission value exceeding the class permission count [ Upstream
Commit: 6c2ab7c4549f4f2305848df834e784651dbf1676
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=6c2ab7c4549f4f2305848df834e784651dbf1676
Changed files:
security/selinux/ss/policydb.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=6c2ab7c4549f4f2305848df834e784651dbf1676
======================================================================
DETAILED REPORT METHODOLOGY
======================================================================
The original Linux kernel CVE announcement for CVE-2026-80755 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80755
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:L/PR:H/UI:N/S:U/C:L/I:L/A:H
The Best / paranoid CVSS vector: AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
The Best / paranoid CVSS score: 7
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: 7
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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