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CVE-2026-28221· NVD / CVE Program· CNA GitHub_M

Wazuh: Pre-auth stack-based buffer overflow in wazuh-remoted print_hex_string() due to signed char promotion on x86_64

Noroxi assessment

Priority: Monitor (action score 32/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.57% (FIRST EPSS).
  • Anyone who can reach it over the internet can trigger it. No account or password is required. No user action is required. No special conditions are required; it is repeatable.
  • According to CISA the attack is automatable: targets can be found by mass scanning.
  • Fixed version: wazuh wazuh 4.14.4.
  • Mentioned 1 time in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Low priority for now. Upgrade to wazuh wazuh 4.14.4 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

Wazuh is a free and open source platform used for threat prevention, detection, and response. From version 4.8.0 to before version 4.14.4, a stack-based buffer overflow exists in print_hex_string() in wazuh-remoted. The bug is triggered when formatting attacker-controlled bytes using sprintf(dst_buf + 2*i, "%.2x", src_buf[i]) on platforms where char is treated as signed and the compiled code sign-extends bytes before the variadic call. For input bytes such as 0xFF, the formatting can emit "ffffffff" (8 chars) instead of "ff" (2 chars), causing an out-of-bounds write past a fixed 2049-byte stack buffer. The vulnerable path is reachable remotely prior to any agent authentication/registration logic via TCP/1514 when an oversized length prefix causes the “unexpected message (hex)” diagnostic path to run. Additionally, the same unauthenticated oversized-message diagnostic path logs an attacker-controlled hex dump to /var/ossec/logs/ossec.log for each trigger, allowing remote log amplification that can degrade monitoring fidelity and consume disk/I/O. This log amplification is reachable even without triggering the sign-extension overflow (e.g., using bytes < 0x80). This issue has been patched in version 4.14.4.

HighCVSS 8.2 · v3.1—No exploit Fix available
Published
Apr 29, 2026
Updated
Jun 17, 2026
EPSS
0.5% · 46th percentile

Report tools

JSON

Action score

32

Monitor

Low priority for now.

CVSS
32 / 40 · 8.2 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.5%

CISA SSVC decision

Exploitation
proof of concept
Automatable
yes
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
8.2
CNA · GitHub_M
6.5
1.7 point gap

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

If any of these changes, we'll tell you in the daily email digest.

Follow CVE-2026-28221

When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
wazuhwazuh

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • wazuh wazuh4.8.0 and later · before 4.14.4

Versions reported by the vendor

Affected version ranges reported by the assigning authority (GitHub_M). Independent of NVD's CPE analysis and usually ahead of it.

  • wazuh wazuh

    • >= 4.8.0, < 4.14.4affected

Same product

wazuh: all records

Other highest-scoring records for the same primary product.

  • CVE-2025-24016Remote code execution in Wazuh serverKEV
    97Now
  • CVE-2023-50260Wazuh's vulnerability in host_deny AR script allows arbitrary command execution
    47Plan
  • CVE-2021-44079In the wazuh-slack active response script in Wazuh 4.2.x before 4.2.5, untrusted user agents are passed to a curl command line, potentially
    40Plan

Published before and after this one in the same product

  • ← EarlierCVE-2026-26204Apr 29, 2026 · Wazuh: Heap-based NULL WRITE Buffer Underflow in GetAlertData
    22Monitor
  • ← EarlierCVE-2026-26206Apr 29, 2026 · Wazuh: API brute-force protection bypass via race condition in login attempt tracking
    26Monitor
  • Later →CVE-2026-30893Apr 29, 2026 · Wazuh cluster sync path traversal in decompress_files() enables arbitrary file write and code execution from authenticated cluster peer
    39Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
wazuh wazuh4.14.4 · descriptionVendor (CNA)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

  • CVE-2026-45798112 days apartWazuh: Pre-auth stack-buffer-overflow in compare_wazuh_versions reachable from wazuh-authd (TCP/1515) via crafted enrollment V: field
    30Monitor
  • CVE-2026-2577243 days apartWazuh Database Synchronization Vulnerable to Stack-based Buffer Overflow via snprintf Integer Underflow
    28Monitor
  • CVE-2026-2579043 days apartWazuh has Stack-Based Buffer Overflow in Security Configuration Assessment JSON Parser
    28Monitor

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

National notice (Türkiye Cybersecurity Directorate / USOM)

Official security notices citing this record; remediation advice is on the agency's page.

All national notices →

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • No account or password is required.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
none
Integrity
low · data or configuration can be modified
Availability
high · the service can be disrupted
Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality impact
None
Integrity impact
Low
Availability impact
High

Weakness class (CWE)

CWE-121 · Stack-based Buffer Overflow

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H

nvd-primary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Change log

  1. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records