BlackTreeCVE Intelligence
← Back to the CVE catalogue
Full vulnerability report · 2026
CVE-2026-44254High confidence

Wazuh: Stack Out-of-Bounds Write in remoted Decompression Path

wazuh · wazuh

Official source article: GitHub GHSA-9WM4-FP6C-HQGQ ↗. Check the applicable product and release in the original source.

5.3MediumCVSS 3.1
Recommended action
Within 7 days

Medium technical severity with public exploit material referenced by a structured source; prioritise exposed affected systems while verifying vendor guidance.

Patch available
R
Operational reassessment

Published severity in operational context

Open reassessment dashboard →
Published severityMediumOperational priority:High, raised one band.upgradedsince 19 Aug 2026

Evidence used

  • No CISA KEV confirmation is currently recorded.
  • A structured source references public exploit or proof-of-concept material.
  • EPSS is 0.50% for the current model date.

Compensating controls

  • Validate the affected product branch and deploy the verified fixed release.
  • Restrict the affected network interface to trusted sources where business-safe.
  • Increase monitoring for the attack path and post-exploitation behaviour described in the report.

Verification

  1. Confirm that the asset runs wazuh wazuh 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-2026-62554

No EUVD known-exploited evidence

Wazuh is a free and open source platform used for threat prevention, detection, and response. From 1.0.0 until 4.14.6 and 5.0.0-beta2, HandleSecureMessage() in src/remoted/secure.c passes a pointer inside its stack buffer to ReadSecMSG(), and src/os_crypto/shared/msgs.c decompresses up to OS_MAXSTR bytes at that offset. For an encrypted agent message on TCP port 1514 that expands to 65,536 bytes, os_zlib_uncompress() writes a terminating null byte beyond the end of the destination buffer. The resulting stack out-of-bounds write in the root-level remoted daemon can crash message processing and disrupt agent communications. This issue is fixed in versions 4.14.6 and 5.0.0-beta2.

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

Medium technical severity with public exploit material referenced by a structured source; prioritise exposed affected systems while verifying vendor guidance.

Patch available
01

What, why and how

Wazuh is a free and open source platform used for threat prevention, detection, and response. From 1.0.0 until 4.14.6 and 5.0.0-beta2, HandleSecureMessage() in src/remoted/secure.c passes a pointer inside its stack buffer to ReadSecMSG(), and src/os_crypto/shared/msgs.c decompresses up to OS_MAXSTR bytes at that offset. For an encrypted agent message on TCP port 1514 that expands to 65,536 bytes, os_zlib_uncompress() writes a terminating null byte beyond the end of the destination buffer. The resulting stack out-of-bounds write in the root-level remoted daemon can crash message processing and disrupt agent communications. This issue is fixed in versions 4.14.6 and 5.0.0-beta2.

What

Wazuh is a free and open source platform used for threat prevention, detection, and response. From 1.0.0 until 4.14.6 and 5.0.0-beta2, HandleSecureMessage() in src/remoted/secure.c passes a pointer inside its stack buffer to ReadSecMSG(), and src/os_crypto/shared/msgs.c decompresses up to OS_MAXSTR bytes at that offset. For an encrypted agent message on TCP port 1514 that expands to 65,536 bytes, os_zlib_uncompress() writes a terminating null byte beyond the end of the destination buffer. The resulting stack out-of-bounds write in the root-level remoted daemon can crash message processing and disrupt agent communications. This issue is fixed in versions 4.14.6 and 5.0.0-beta2.

Why

The product does not correctly calculate the size to be used when allocating a buffer, which could lead to a buffer overflow.

How

An attacker operating through a network path may attempt exploitation with low privileges. If successful, the issue may disrupt the affected service.

What

Wazuh is a free and open source platform used for threat prevention, detection, and response. From 1.0.0 until 4.14.6 and 5.0.0-beta2, HandleSecureMessage() in src/remoted/secure.c passes a pointer inside its stack buffer to ReadSecMSG(), and src/os_crypto/shared/msgs.c decompresses up to OS_MAXSTR bytes at that offset. For an encrypted agent message on TCP port 1514 that expands to 65,536 bytes, os_zlib_uncompress() writes a terminating null byte beyond the end of the destination buffer. The resulting stack out-of-bounds write in the root-level remoted daemon can crash message processing and disrupt agent communications. This issue is fixed in versions 4.14.6 and 5.0.0-beta2.

Why

The product does not correctly calculate the size to be used when allocating a buffer, which could lead to a buffer overflow.

How

An attacker operating through a network path may attempt exploitation with low privileges. If successful, the issue may disrupt the affected service.

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.
Reference recorded

A structured CVE source labels at least one public reference as exploit material. BlackTree has not independently validated that it is safe, reliable or weaponised.

Likely attack path
a network path → Incorrect Calculation of Buffer Size → disrupt the affected service
Attack surface
Network
Privileges required
Low: a basic authenticated account is required
User interaction
None
Attack complexity
High: exploitation depends on specific conditions
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-131 ↗

CWE-131: Incorrect Calculation of Buffer Size. The product does not correctly calculate the size to be used when allocating a buffer, which could lead to a buffer overflow.

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

Common Vulnerability Scoring System 3.1: the compact vector below is decoded into plain language.

AVNetworkAttack vector: The vulnerable component can be reached over a network.ACHighAttack complexity: Successful exploitation depends on specific conditions outside the attacker's direct control.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.CNoneConfidentiality impact: No direct loss is represented by this metric.INoneIntegrity impact: No direct loss is represented by this metric.AHighAvailability impact: A successful attack can cause a major loss.
Post-exploitation / living off the land
No specific living-off-the-land technique is confirmed in the structured sources. Monitor normal administration tools for activity inconsistent with the affected service's baseline.
NetworkDenial of serviceCWE-131Public exploit reference
A

Official authority intelligence

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

ENISA EUVD · EUVD-2026-62554Official EUVD mapping

Wazuh is a free and open source platform used for threat prevention, detection, and response. From 1.0.0 until 4.14.6 and 5.0.0-beta2, HandleSecureMessage() in src/remoted/secure.c passes a pointer inside its stack buffer to ReadSecMSG(), and src/os_crypto/shared/msgs.c decompresses up to OS_MAXSTR bytes at that offset. For an encrypted agent message on TCP port 1514 that expands to 65,536 bytes, os_zlib_uncompress() writes a terminating null byte beyond the end of the destination buffer. The resulting stack out-of-bounds write in the root-level remoted daemon can crash message processing and disrupt agent communications. This issue is fixed in versions 4.14.6 and 5.0.0-beta2.

Official EUVD record ↗
BSI · German · WID-SEC-2026-2699Wazuh: Mehrere Schwachstellen

Ein Angreifer kann mehrere Schwachstellen in Wazuh ausnutzen, um beliebigen Programmcode auszuführen, um seine Privilegien zu erhöhen, um einen Denial of Service Angriff durchzuführen, um Informationen offenzulegen, um Dateien zu manipulieren, und um einen SQL-Injection Angriff durchzuführen.

Official advisory ↗
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 ↗
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
wazuh: 1.0.0, < 4.14.6, 5.0.0-beta1, < 5.0.0-beta2
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. If business-safe, reduce exposure to the affected interface and allow only trusted sources until authoritative guidance is available.
Official vendor articles3 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 19 Aug 2026 · Last source change 19 Aug 2026, 18:18 UTC · CWE-131 · Incorrect Calculation of Buffer Size

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-2026-62554
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 patch: github.com/35773; added patch: github.com/96772487fbdecd43cc83e284ee7aeb45e3cfcd96; 2 further additions.
    Before
    no authoritative guidance recorded
    After
    patch: github.com/35773 · patch: github.com/96772487fbdecd43cc83e284ee7aeb45e3cfcd96 · remediation: github.com/35773 · 1 more references
    security-advisories@github.com ↗
  2. Affected versionsThe structured affected or fixed version information changed.
    Before
    >= 1.0.0, < 4.14.6; >= 5.0.0-beta1, < 5.0.0-beta2 · Fixed: No fixed version is explicitly recorded in the structured CVE data.
    After
    wazuh: >= 1.0.0, < 4.14.6, >= 5.0.0-beta1, < 5.0.0-beta2 · 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.
    CNA ↗
  3. Remediation statusRemediation status changed from Awaiting fix to Patch available.
    Before
    Awaiting fix
    After
    Patch available
    security-advisories@github.com ↗
  4. Public exploit evidencePublic exploit evidence changed from No public exploit to Public exploit reference.
    Before
    No public exploit
    After
    Public exploit reference
    security-advisories@github.com ↗
  5. Catalogue recordCVE added to the BlackTree catalogue.
    CNA ↗
Material fields only · duplicate refreshes suppressed · history retained for the configured operational retention period
CVE published
Fixed release or patch reference recorded
ENISA EUVD · EUVD-2026-62554↗Public exploit reference · GitHub GHSA-9WM4-FP6C-HQGQ↗Patch or update reference↗Patch or update 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-2026-44254 · cve.blacktree.nl