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Full vulnerability report · 2026
CVE-2026-58094High confidence

TOCTOU race in POSIX shared memory large page configuration

FreeBSD · FreeBSD

7.8HighCVSS 3.1
Recommended action
Within 7 days

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

Fix not verified
R
Operational reassessment

Published severity in operational context

Open reassessment dashboard →
Published severityHighOperational priority:Medium, lowered one band.downgradedsince 26 Aug 2026

Evidence used

  • No CISA KEV confirmation is currently recorded.
  • Exploitation requires an existing local or physical foothold with privileges.
  • EPSS is 0.12% for the current model date.

Compensating controls

  • 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 FreeBSD FreeBSD and falls inside the recorded affected range.
  2. Recheck the vendor advisory before scheduling a change because no verified fixed version is currently retained.
  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: As exposure requiresRemediation target: Within 365 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-2026-66253

No EUVD known-exploited evidence

The FIOSSHMLPGCNF ioctl(2) operation configures the page size for a largepage shared memory object. This is intended to be used immediately after creating the object, before any memory is allocated for the object. The handler checked whether a page size had already been configured without holding the rangelock. Two concurrent callers could both observe an unconfigured object and set conflicting page sizes, leaving the object in an inconsistent state. An unprivileged local user can exploit this race to escalate privileges.

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
7.8 · CVSS 3.1
Advisory evidence
No linked advisory details stored yet
Recommended actionWithin 7 days

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

Fix not verified
01

What, why and how

The FIOSSHMLPGCNF ioctl(2) operation configures the page size for a largepage shared memory object. This is intended to be used immediately after creating the object, before any memory is allocated for the object. The handler checked whether a page size had already been configured without holding the rangelock. Two concurrent callers could both observe an unconfigured object and set conflicting page sizes, leaving the object in an inconsistent state. An unprivileged local user can exploit this race to escalate privileges.

What

The FIOSSHMLPGCNF ioctl(2) operation configures the page size for a largepage shared memory object. This is intended to be used immediately after creating the object, before any memory is allocated for the object. The handler checked whether a page size had already been configured without holding the rangelock. Two concurrent callers could both observe an unconfigured object and set conflicting page sizes, leaving the object in an inconsistent state. An unprivileged local user can exploit this race to escalate privileges.

Why

The product checks the state of a resource before using that resource, but the resource's state can change between the check and the use in a way that invalidates the results of the check.

How

An attacker operating through local access may attempt exploitation with low privileges. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.

What

The FIOSSHMLPGCNF ioctl(2) operation configures the page size for a largepage shared memory object. This is intended to be used immediately after creating the object, before any memory is allocated for the object. The handler checked whether a page size had already been configured without holding the rangelock. Two concurrent callers could both observe an unconfigured object and set conflicting page sizes, leaving the object in an inconsistent state. An unprivileged local user can exploit this race to escalate privileges.

Why

The product checks the state of a resource before using that resource, but the resource's state can change between the check and the use in a way that invalidates the results of the check.

How

An attacker operating through local access may attempt exploitation with low privileges. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.

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 → Time-of-check Time-of-use (TOCTOU) Race Condition → cause the confidentiality, integrity or availability impact described by the vendor
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
Unchanged: impact remains within the vulnerable component's security authority
Weakness
?CWE means Common Weakness Enumeration: a standard category for the underlying weakness.
CWE-367 ↗

CWE-367: Time-of-check Time-of-use (TOCTOU) Race Condition. The product checks the state of a resource before using that resource, but the resource's state can change between the check and the use in a way that invalidates the results of the check.

CVSS vector
?CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity.
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Common Vulnerability Scoring System 3.1: 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.PRLowPrivileges required: The attacker needs basic user-level privileges.UINoneUser interaction: No action by another user is required.SUnchangedScope: The security impact remains within the vulnerable component's authority.CHighConfidentiality impact: A successful attack can cause a major loss.IHighIntegrity impact: A successful attack can cause a major loss.AHighAvailability impact: A successful attack can cause a major loss.
Post-exploitation / living off the land
The issue can support a local privilege or sandbox boundary transition; normal system utilities may then be available in the gained context.
CWE-367
A

Official authority intelligence

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

ENISA EUVD · EUVD-2026-66253Official EUVD mapping

The FIOSSHMLPGCNF ioctl(2) operation configures the page size for a largepage shared memory object. This is intended to be used immediately after creating the object, before any memory is allocated for the object. The handler checked whether a page size had already been configured without holding the rangelock. Two concurrent callers could both observe an unconfigured object and set conflicting page sizes, leaving the object in an inconsistent state. An unprivileged local user can exploit this race to escalate privileges.

Official EUVD record ↗
BSI · German · WID-SEC-2026-3034FreeBSD Project FreeBSD OS: Mehrere Schwachstellen

Ein Angreifer kann mehrere Schwachstellen in FreeBSD Project FreeBSD OS ausnutzen, um Berechtigungen zu erweitern und möglicherweise Root-Rechte zu erlangen, Sicherheitsmaßnahmen zu umgehen, beliebigen Code auszuführen, Daten zu manipulieren oder offenzulegen oder Denial-of-Service-Zustände herbeizuführen.

Official advisory ↗
Cyber Security Agency of Singapore · English · CSA-SB-20260902Security Bulletin 2 Sept 2026

The Cyber Security Agency of Singapore included this CVE in its official Security Bulletin 2 Sept 2026, published on 2 September 2026. Open the linked bulletin for the product, severity and reference information published in that issue.

Official advisory ↗
JVN iPedia · Japanese · JVNDB-2026-035388FreeBSDにおけるTime-of-check Time-of-use (TOCTOU) 競合状態の脆弱性

FIOSSHMLPGCNF ioctl(2) 操作は、大きなページの共有メモリオブジェクトのページサイズを構成します。これはオブジェクト作成直後、メモリが割り当てられる前に使用することを意図しています。ハンドラはrangelock を保持せずにページサイズが既に設定されているかどうかを確認しました。2つの同時呼び出しはどちらも未設定のオブジェクトを観測し、それぞれ異なるページサイズを設定してしまい、オブジェクトを一貫性のない状態にしてしまいました。権限のないローカルユーザーは、この競合状態を悪用して権限昇格を行うことが可能です。

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.
Fix not verified
Affected
FreeBSD: 15.1-RELEASE < p3, 15.0-RELEASE < p13, 14.4-RELEASE < p9
Fixed
No fixed version is explicitly recorded in the structured CVE data.
Action
No verified patch reference is present in the current structured sources. Check the vendor advisory before making a change.
Workaround
No verified workaround is recorded. Limit untrusted access and use least privilege until authoritative guidance is available.
04

Evidence and provenance

Published 26 Aug 2026 · Last source change 27 Aug 2026, 03:57 UTC · CWE-367 · Time-of-check Time-of-use (TOCTOU) Race Condition

CVE recordCVE.org · 5.2
CVSS sourceCISA ADP
EPSS source
?The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.
FIRST · tracked since 2026-08-26
European sourceENISA EUVD · EUVD-2026-66253
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. Vendor guidanceAuthoritative vendor guidance changed: added vendor advisory: security.freebsd.org/FreeBSD-SA-26:63.posixshm.asc.
    Before
    no authoritative guidance recorded
    After
    vendor advisory: security.freebsd.org/FreeBSD-SA-26:63.posixshm.asc
    secteam@freebsd.org ↗
  2. Affected versionsThe structured affected or fixed version information changed.
    Before
    15.1-RELEASE < p3; 15.0-RELEASE < p13; 14.4-RELEASE < p9 · Fixed: No fixed version is explicitly recorded in the structured CVE data.
    After
    FreeBSD: 15.1-RELEASE < p3, 15.0-RELEASE < p13, 14.4-RELEASE < p9 · Fixed: No fixed version is explicitly recorded in the structured CVE data.
    CNA ↗
  3. ENISA EUVD mappingEUVD-2026-66253 was added to the official ENISA EUVD mapping for this CVE.
    Before
    not recorded
    After
    {"euvdId":"EUVD-2026-66253"}
    ENISA EUVD ↗
  4. SeveritySeverity changed from Unknown to High.
    Before
    Unknown
    After
    High
    CISA ADP ↗
  5. CVSS scoreCVSS score changed from not recorded to 7.8 (CVSS 3.1 · CISA ADP · CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H).
    Before
    not recorded
    After
    7.8 (CVSS 3.1 · CISA ADP · CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H)
    CISA ADP ↗
  6. Vendor guidanceAuthoritative vendor guidance changed: removed vendor advisory: security.freebsd.org/FreeBSD-SA-26:63.posixshm.asc.
    Before
    vendor advisory: security.freebsd.org/FreeBSD-SA-26:63.posixshm.asc
    After
    no authoritative guidance recorded
    CNA ↗
  7. 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-2026-66253↗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-2026-58094 · cve.blacktree.nl