nanoMODBUS Server-Side Out-of-Bounds Write in handle_read_file_record()
CVSS score
9.8
EPSS probability
%0.6
Risk score
0.1
Published
2 mo ago
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Vulnerability description
CVE AI research
DayBreach AI Explanation
Verified against sourcesSources read
1
Source agreement
Tam uyum
Evidence confidence
%53
Short explanation
CVE-2026-71254 in nanoMODBUS v1.23.0 allows unauthenticated remote clients to trigger an out-of-bounds write via a crafted Modbus FC 0x14 request, leading to denial of service or remote code execution due to buffer overflow in handle_read_file_record(). Patch status is UNKNOWN.
This vulnerability allows remote attackers to exploit a buffer overflow in an unauthenticated Modbus server, potentially leading to full system compromise. It affects embedded systems with minimal memory protection, making it a high-risk issue for industrial IoT devices.
What should be done?
- Apply vendor patch if available (no fixed version known)
- Follow vendor advisory for mitigation
- Do not use nanoMODBUS v1.23.0 or earlier in unpatched environments
The sources give limited detail on some technical conditions. Review the chain of evidence below before deciding how to act.
Chain of evidence and sources
CVE-2026-71254, nanoMODBUS 1.23.0 ve altında, bir bilinmeyen ağ istemcisi tarafından oluşturulan bir Modbus FC 0x14 isteğiyle, handle_read_file_record() fonksiyonunda bir sınır dışı yazma tetiklenebilir. Bu, 260-byte buffer'dan dışına yazma nedeniyle hizmetin durdurulması ya da özellikle bellek koruma yoksa uzak kod yürütme olasılığına neden olur.
nanoMODBUS'da handle_read_file_record() fonksiyonunda, alt isteklerin işlendiği önceden toplam yanıt boyutunun doğrulandığı yoktur. Bu nedenle uint8_t toplama değişkeni aşılmış ve sınırsız bellek erişimi oluşur.
Açık, CVSS 3.1 puanı 9.1 (Kritik) ile değerlendirilir. Resmî kaynaklarda yama veya düzeltme sürümü bilinmemektedir ve yama durumu 'Bilinmeyen' olarak değerlendirilir.
Show the technical text from the sources
nanoMODBUS through v1.23.0 contains an out-of-bounds write in the Modbus server-side handle_read_file_record function (FC 0x14, Read File Record) in nanomodbus.c. The function validates that the total request size does not exceed 245 bytes and that each sub-request's record_length is at most 124, but it never validates the CUMULATIVE response size across all sub-requests before processing them.
CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CWE: CWE-787
Explanation produced with the local qwen3:4b-instruct model. Numerical metrics and the KEV, patch and exploit statuses are not determined by AI.
IMPACT: Affected Products and Software
Affected Products
The following products are affected by CVE-2026-71254 vulnerability. Where our threat engine knows the exact affected versions, they are listed below.
| ID | VENDOR | PRODUCT | ACTION |
|---|---|---|---|
| 1 | debevv | nanoMODBUS | View |
RED HAT CSAF/VEX: Product Impact Check
SCORING: CVSS from Multiple Sources
CVSS Scores
The Common Vulnerability Scoring System is a standardised framework for assessing the severity of vulnerabilities in software and systems. We collect and display CVSS scores from several sources for each CVE.
| SCORE | VERSION | SEVERITY | VECTOR | SOURCE |
|---|---|---|---|---|
| 9.8 | CVSS V3_1 | CRITICAL | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H | CVE CNA |
| 9.8 | CVSS V31 | CRITICAL | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H | NVD |
Patch and Remediation Guide
Solution & Remediation Advisory
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Public exploit and active exploitation status
Verified exploit intelligence
No verified public PoC, exploit repository or Metasploit module has been found for this CVE yet.
Weakness Classification and Attack Patterns (CWE & CAPEC)
CWE - Common Weakness Enumeration
While CVE identifies specific instances of vulnerabilities, CWE categorises the common flaws or weaknesses that can lead to vulnerabilities. CVE-2026-71254 is associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification (CAPEC) stores attack patterns, which are descriptions of the common attributes and approaches employed by adversaries to exploit the CVE-2026-71254 weaknesses.
Attack Vector and Accessibility
Official Sources and Advisories
Similar Vulnerabilities
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