Quick answers
- Is CVE-2026-38426 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-38426 being exploited in the wild.
- How severe is CVE-2026-38426?
- Informational severity, with a CVSS score of 9.8, published 27 May 2026.
- Which products and versions are affected?
- Tasmota <= 15.3.0.3.
- Is there a fix for CVE-2026-38426?
- A patch was published on 2026-05-01: Patch released in v15.3.0.4 (approximate date based on advisory) Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
- How is CVE-2026-38426 attacked?
- It is attacked over the network, in an operating system.
- Am I affected by CVE-2026-38426?
- Check whether you run Tasmota at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.
Technical details
A stack-based buffer overflow exists in the fetch_jpg() function within xdrv_10_scripter.ino. The vulnerability is caused by the use of the unsafe strcpy() function when copying the MJPEG boundary string from an HTTP Content-Type header into a fixed-size 40-byte buffer (jpg_task.boundary). An attacker-controlled HTTP server can provide a boundary string exceeding 39 characters to overflow the buffer. This allows for the corruption of adjacent heap memory, specifically overwriting vtable pointers for WiFiClient or HTTPClient objects, leading to remote code execution (RCE) on the ESP32 platform. The issue is addressed in Tasmota version 15.3.0.4 and later.
Affected products
- arendst Tasmota <= 15.3.0.3
Timeline
- 2026-03-29: disclosed: Vulnerability discovered and reported to MITRE
- 2026-05-27: advisory: CVE published by NVD
- 2026-05-01: patched: Patch released in v15.3.0.4 (approximate date based on advisory)