dbcve.org
Heap-based Buffer OverflowWeakness · CWE-122

CVE-2026-51270

HIGH · 8.8 CVSS v3.1 Published 2026-07-28
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
95/100
Remediation priority · Urgent
Remotely reachable No privileges 3 weeks old

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
schreibfaul1 ESP32-audioI2S 3.4.5 has a heap-based buffer overflow vulnerability in the htmlToUTF8() HTML entity decoding function. The function parses attacker-controlled malicious HTML entities and uses memmove and memcpy to rearrange string content without validating buffer remaining size and boundary limits. Crafted oversized HTML entity strings can trigger heap out-of-bounds write, allowing remote code execution, memory information leakage, service crash or privilege escalation.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · moderate confidence

Heap-based buffer overflow in ESP32-audioI2S library version 3.4.5's htmlToUTF8() function during HTML entity decoding. The function uses memmove and memcpy to manipulate string content without validating buffer remaining size or boundaries, allowing attacker-controlled oversized HTML entity strings to trigger out-of-bounds writes leading to RCE, memory leakage, DoS, or privilege escalation.

MitigationImplement strict bounds checking and buffer size validation in htmlToUTF8() before memmove/memcpy operations; add input length limits for HTML entity strings; update to patched version when available.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
Required
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

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

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Locate ESP32-audioI2S library installation
    Navigate to your Arduino libraries folder (typically ~/Arduino/libraries/ or your PlatformIO lib/ directory) and locate the 'ESP32-audioI2S' folder. Check for a version identifier in the folder name, library.properties file, or any version metadata file.
    Affected if The library folder exists and contains ESP32-audioI2S files, indicating this library is in use.
  2. Identify installed library version
    Open the library.properties file within the ESP32-audioI2S directory and locate the 'version' field. Alternatively, check the main header file (e.g., ESP32_AudioI2S.h) for version comments or defines.
    Affected if The reported version matches 3.4.5 exactly, or falls within the affected range around 3.4.5.
  3. Locate htmlToUTF8 function in source
    Search within the ESP32-audioI2S library source files (look for .cpp and .h files) for the string 'htmlToUTF8' to confirm the function exists in your installed version.
    Affected if The htmlToUTF8 function is present in the library code, meaning the vulnerable code path exists.
  4. Determine if HTML entity processing is active
    Review your sketch or application code that uses the ESP32-audioI2S library. Look for calls to functions that process streaming metadata, web radio responses, or any function that could pass HTML entities to the library (common withICY metadata parsing for internet radio streams).
    Affected if Your code uses the library to process remote audio streams or metadata that could contain HTML entities.
  5. Inspect htmlToUTF8 for bounds checking
    Open the source file containing htmlToUTF8 (found in step 3) and examine the function implementation. Look for memmove or memcpy calls without corresponding buffer size validation or length checks before them.
    Affected if The function contains memmove or memcpy operations without proper bounds checking before the call, matching the described vulnerability.

You are affected if the ESP32-audioI2S library version is 3.4.5 or nearby, the htmlToUTF8 function is present, and your application uses the library to process external HTML content such as streaming metadata.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

From vendor data
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Implement strict bounds checking and buffer size validation in htmlToUTF8() before memmove/memcpy operations; add input length limits for HTML entity strings; update to patched version when available.

Have this fixed Scoped from the published advisory
  • Consultation3.0 h
  • Implementation8.0 h
  • Testing4.0 h
  • Review / QA2.0 h
17.0 hours of engineering $3,000
Get help mitigating

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $4,800.

Scan for this in your stack

Free · runs locally
dbcve dependency scanner

Check whether your project pulls in CVE-2026-51270 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.

Get it on GitHub Scan in the browser

References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-51270 in production — separate from our analysis above.

No notes yet

Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.

What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data