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Full vulnerability report · 2026
CVE-2026-77234High confidence

Improper input validation in FreeRTOS-Kernel timer command handling

FreeRTOS · FreeRTOS-Kernel

Official source article: GitHub GHSA-W3VR-PR75-5HC6 ↗. Check the applicable product and release in the original source.

9.3CriticalCVSS 4.0
Recommended action
Within 7 days

Critical technical severity; prioritise exposed affected systems while verifying vendor guidance.

Patch available
R
Operational reassessment

Published severity in operational context

Open reassessment dashboard →
Published severityCriticalOperational priority:High, lowered one band.downgradedsince 27 Aug 2026

Evidence used

  • No CISA KEV confirmation is currently recorded.
  • Exploitation requires an existing local or physical foothold with privileges.
  • EPSS is 0.17% for the current model date.

Compensating controls

  • Validate the affected product branch and deploy the verified fixed release.
  • Restrict local access and enforce least privilege on affected hosts.
  • Monitor vendor guidance and exploitation sources for a material change.

Verification

  1. Confirm that the asset runs FreeRTOS FreeRTOS-Kernel and falls inside the recorded affected range.
  2. Verify the installed build against the product-specific fixed version after deployment.
  3. Validate exposure, authentication requirements and compensating controls in the actual environment.
  4. Reopen this reassessment when CVSS, KEV, EPSS, exploit evidence or remediation changes.
Mitigation target: Within 30 daysRemediation target: Within 180 days

This automated reassessment organises public evidence. It does not know asset exposure, business impact or control effectiveness and does not replace CVSS or a human risk decision.

Optional official sources

National CERT insights
?CERT means Computer Emergency Response Team; CSIRT is the closely related term Computer Security Incident Response Team.

Choose official national sources for this report. Each advisory shows its original language. Your selection is remembered on this device and included in shared links.

Official European source

ENISA European Vulnerability Database

Official EUVD identifiers, advisory evidence and known-exploited context. Missing fields are not treated as evidence of low risk.

1 current
ENISA EUVD identifier

EUVD-2026-64012

No EUVD known-exploited evidence

Improper input validation in FreeRTOS-Kernel before 11.3.1 might allow an unprivileged task on MPU-enabled ports to execute code in privileged kernel context. To remediate this issue, users should upgrade to version 11.3.1 or later.

EUVD state
Present in the current official mapping
Known exploitation
Not present in the current ENISA EUVD known-exploited dataset. This is not proof of no exploitation.
ENISA score
9.3 · CVSS 4.0
Advisory evidence
No linked advisory details stored yet
Recommended actionWithin 7 days

Critical technical severity; prioritise exposed affected systems while verifying vendor guidance.

Patch available
01

What, why and how

Improper input validation in FreeRTOS-Kernel before 11.3.1 might allow an unprivileged task on MPU-enabled ports to execute code in privileged kernel context. To remediate this issue, users should upgrade to version 11.3.1 or later.

What

Improper input validation in FreeRTOS-Kernel before 11.3.1 might allow an unprivileged task on MPU-enabled ports to execute code in privileged kernel context. To remediate this issue, users should upgrade to version 11.3.1 or later.

Why

The application performs an authorisation check, but it does not correctly enforce the required permission boundary.

How

An attacker operating through local access may attempt exploitation with low privileges. If successful, the issue may execute code or commands in the affected security context.

What

Improper input validation in FreeRTOS-Kernel before 11.3.1 might allow an unprivileged task on MPU-enabled ports to execute code in privileged kernel context. To remediate this issue, users should upgrade to version 11.3.1 or later.

Why

The application performs an authorisation check, but it does not correctly enforce the required permission boundary.

How

An attacker operating through local access may attempt exploitation with low privileges. If successful, the issue may execute code or commands in the affected security context.

02

Exploit reality and attack path

CVSS severity, EPSS forecast probability, public exploit material and CISA-confirmed exploitation are separate signals.

Observed exploitation
?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.
No confirmed evidence

No CISA KEV match was present at the last successful refresh. This means no confirmation from that source, not proof of no exploitation.

Public PoC / exploit material
?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.
None recorded

No exploit-tagged reference or CISA SSVC proof-of-concept state is currently recorded. Research may still exist outside the structured feeds.

Likely attack path
local access → Incorrect Authorization → execute code or commands in the affected security context
Attack surface
Local
Privileges required
Low: a basic authenticated account is required
User interaction
None
Attack complexity
Low: no specialised conditions are recorded
Security boundary
Not a CVSS 4.0 base metric
Weakness
?CWE means Common Weakness Enumeration: a standard category for the underlying weakness.
CWE-863 ↗

CWE-863: Incorrect Authorization. The product performs an authorization check when an actor attempts to access a resource or perform an action, but it does not correctly perform the check.

CVSS vector
?CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity.
CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H

Common Vulnerability Scoring System 4.0: the compact vector below is decoded into plain language.

AVLocalAttack vector: The attacker needs local access to the vulnerable system.ACLowAttack complexity: No specialised conditions are required beyond attacker-controlled input.ATNoneAttack requirements: No additional deployment or execution condition is required.PRLowPrivileges required: The attacker needs basic user-level privileges.UINoneUser interaction: No action by another user is required.VCHighVulnerable-system confidentiality: A successful attack can cause a major loss.VIHighVulnerable-system integrity: A successful attack can cause a major loss.VAHighVulnerable-system availability: A successful attack can cause a major loss.SCHighSubsequent-system confidentiality: A successful attack can cause a major loss.SIHighSubsequent-system integrity: A successful attack can cause a major loss.SAHighSubsequent-system availability: A successful attack can cause a major loss.
Post-exploitation / living off the land
After compromise, an attacker may use built-in shells, scripting engines, scheduled tasks and native network utilities for discovery, persistence or movement. This is a plausible LoTL path, not evidence that it has occurred for every attack.
Remote code executionCWE-863
A

Official authority intelligence

Only matched European and national findings are included. Language selectors and unavailable sources are omitted.

ENISA EUVD · EUVD-2026-64012Official EUVD mapping

Improper input validation in FreeRTOS-Kernel before 11.3.1 might allow an unprivileged task on MPU-enabled ports to execute code in privileged kernel context. To remediate this issue, users should upgrade to version 11.3.1 or later.

Official EUVD record ↗
Cyber Security Agency of Singapore · English · CSA-SB-20260826Security Bulletin 26 Aug 2026

The Cyber Security Agency of Singapore included this CVE in its official Security Bulletin 26 Aug 2026, published on 26 August 2026. Open the linked bulletin for the product, severity and reference information published in that issue.

Official advisory ↗
JVN iPedia · Japanese · JVNDB-2026-030194Amazon.com, Inc.のfreertosにおける不正な認証に関する脆弱性

11.3.1以前のFreeRTOS-Kernelでは、不適切な入力検証により、MPU対応ポート上の権限のないタスクが特権カーネルコンテキストでコードを実行できる可能性がありました。この問題を解決するために、ユーザーはバージョン11.3.1以降にアップグレードする必要があります。

Official advisory ↗
JVN iPedia · Japanese · JVNDB-2026-030193Amazon.com, Inc.のfreertosにおける解放済みメモリの使用に関する脆弱性

FreeRTOS-Kernel 11.3.1より前のバージョンにおいて、セキュアコンテキストクリーンアップハンドラで権限確認が欠如しているため、ローカルユーザーがセキュアコンテキスト解放用のSVCハンドラを介してセキュアワールドメモリでuse-after-freeの状態を引き起こす可能性があります。この問題を解決するため、ユーザーはバージョン11.3.1以降にアップグレードする必要があります。

Official advisory ↗
JVN iPedia · Japanese · JVNDB-2026-030192Amazon.com, Inc.のfreertosにおける境界外書き込みに関する脆弱性

FreeRTOS-Kernel 11.3.1より前のバージョンにおいて、安全なコンテキスト割り当て時の最小サイズ検証が欠落しているため、ローカルユーザーがスタックサイズパラメータを過小に指定し、境界外書き込みによってセキュアワールドのヒープメタデータを破損させる可能性があります。この問題を解決するために、ユーザーはバージョン11.3.1以降にアップグレードする必要があります。

Official advisory ↗
JVN iPedia · Japanese · JVNDB-2026-030191Amazon.com, Inc.のfreertosにおける複数の脆弱性

FreeRTOS-Kernelのバージョン11.3.1以前のxQueueAddToSet()にはキューセットタイプ検証の欠如があり、configUSE_QUEUE_SETS=1が設定されたMPU対応ポートにおいて権限のないタスクが特権カーネルメモリを読み取る可能性があります。この問題を解決するために、ユーザーはバージョン11.3.1以降にアップグレードする必要があります。

Official advisory ↗
03

Patch and workaround

Operational remediation based on structured source evidence.

Status
?Patch availability is based on structured fixed-version fields and authoritative update references. If no fix is verified, check the vendor advisory before making a change.
Patch available
Affected
FreeRTOS-Kernel: 7.0.0 ≤ 11.3.0
Fixed
An authoritative update reference is available, but the fixed version is not recorded in the structured CVE fields. Check the linked vendor advisory for the applicable release.
Action
Review the linked authoritative reference and apply the recorded fixed release appropriate to the affected product branch.
Workaround
No verified workaround is recorded. Limit untrusted access and use least privilege until authoritative guidance is available.
Official vendor articles2 stored documents

Linked articles are downloaded and versioned as source evidence. A CVE mention or approved update relationship does not, by itself, verify a fix for every product branch.

04

Evidence and provenance

Published 21 Aug 2026 · Last source change 27 Aug 2026, 16:46 UTC · CWE-863 · Incorrect Authorization

CVE recordCVE.org · 5.2
CVSS sourceCNA
EPSS source
?The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.
FIRST · tracked since 2026-08-23
European sourceENISA EUVD · EUVD-2026-64012
Product sourceCNA
Remediation sourceCVE/CNA references
CWE sourceCNA
NVD statusNVD enriched

Core structured fields are present and their contributing authorities are shown above.

Material change intelligence

What changed after publication

View recent updates ↗
  1. ENISA EUVD mappingEUVD-2026-64012 was added to the official ENISA EUVD mapping for this CVE.
    Before
    not recorded
    After
    {"euvdId":"EUVD-2026-64012"}
    ENISA EUVD ↗
  2. Vendor guidanceAuthoritative vendor guidance changed: added vendor advisory: aws.amazon.com/2026-086-aws; added vendor advisory: github.com/GHSA-w3vr-pr75-5hc6.
    Before
    no authoritative guidance recorded
    After
    vendor advisory: aws.amazon.com/2026-086-aws · vendor advisory: github.com/GHSA-w3vr-pr75-5hc6
    aws.amazon.com ↗
  3. Catalogue recordCVE added to the BlackTree catalogue.
    CNA ↗
Material fields only · duplicate refreshes suppressed · history retained for the configured operational retention period
CVE published
ENISA EUVD · EUVD-2026-64012↗Vendor advisory↗Vendor advisory · GitHub GHSA-W3VR-PR75-5HC6↗CVE authority or vendor reference↗Official CVE record (CNA and ADP data)↗NVD record↗
Technical terms and abbreviations used in this report
CVE
Common Vulnerabilities and Exposures: the public identifier for one disclosed vulnerability.
CVSS
Common Vulnerability Scoring System: a technical severity framework; it is not patching priority by itself.
EPSS
Exploit Prediction Scoring System: FIRST's estimate of the probability that exploitation activity will be observed in the next 30 days; it is a forecast, not confirmation.
CWE
Common Weakness Enumeration: the standard category describing the underlying software or hardware weakness.
CNA
CVE Numbering Authority: an organisation authorised to assign and publish CVE records.
CISA ADP
Cybersecurity and Infrastructure Security Agency Authorized Data Publisher: structured enrichment added to a CVE record.
NVD
National Vulnerability Database: NIST's enrichment service for CVE records.
CERT / CSIRT
A computer security incident response team that publishes warnings or coordinates incident response.
PoC
Proof of concept: public material that demonstrates or helps reproduce exploitation.
CSAF
Common Security Advisory Framework: a machine-readable format for security advisories.
LoTL
Living off the land: abuse of legitimate tools or system functions during an attack.
Free version - for non-commercial use only.CVE-2026-77234 · cve.blacktree.nl