Tasmota 16.0.0 Heap Out-of-Bounds Write via Device Groups UDP
Tasmota through 16.0.0 is affected when Device Groups is in use, since it receives messages over UDP port 4447. The fix is commit e97e1e4, and no release version is given. No vendor rating is given.
Written by anthropic/claude-haiku-5.5 from the sources below. Verify against them.
- Exploited
- No known exploitation
- Fix
- Fix or patch referenced
- Who is exposed
- Not reported
Do first: Apply the patch listed under Evidence.
- Last modified
- A 0-100 score for how much a CVE matters across the industry: exploitation, exposure, how widely the software is used, severity and whether a fix exists.What do these mean? →
- 30/100 · provisional
- How many real-world setups can hit the bug, from the vendor's advisory and CISA data. It does not know your setup.What do these mean? →
- Unclear
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
- Exploitation: none
- Automatable: yes
- Technical impact: total
Summary
Tasmota firmware through version 16.0.0 has a heap out-of-bounds write in its Device Groups handling that lets an attacker on the local network corrupt device memory. The attacker reaches it remotely over UDP without logging in, and it can crash the device or potentially run code on ESP8266 and ESP32 devices.
Read the original description
Tasmota through 16.0.0, fixed in commit e97e1e4, contains a heap out-of-bounds write vulnerability in SendReceiveDeviceGroupMessage() that allows unauthenticated attackers on the local network to corrupt heap memory by sending crafted Device Groups messages over UDP port 4447 that cause the log_remaining counter to go negative and writes to exceed the fixed 512-byte buffer. Attackers can exploit this flaw to crash the device or potentially achieve native code execution on ESP8266 and ESP32 platforms that lack ASLR and heap cookies.
cve.now Index
- Exploitation0/40No signal
- Exposure20/25No login or user action needed, CISA rates it automatable · Unknown: Advisories don't say whether default setups are affected
- Reach?/20Unknown. No tracked technology or package matched
- Severity10/10CVSS 9.3, total technical impact per CISA
- No patch0/5No signal
What would change the score
- Would score about 75 if added to CISA KEV
- Would score about 70 if CISA's SSVC rates exploitation active
- Would score about 35 if advisories confirm default setups are exposed
What to do
Apply the patch listed under Evidence.
Timeline
- CVE published
- First seen by cve.now
- Posted on X by cve.now
- CISA SSVC assessment
Exploitation: none · Automatable: yes · Technical impact: total
- Record last updated
Affected versions
- arendst Tasmota
through 16.0.0
Evidence 2
- Patch
- Link
Corrections
None so far.
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Questions about CVE-2026-119756
Is CVE-2026-119756 being exploited?
It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.Source: cve.now feed data
What does this mean?
Crafted Device Groups messages received over UDP port 4447 can write past the end of a heap buffer, corrupting heap memory. This can crash the device or, on ESP8266 and ESP32 devices that lack ASLR and heap cookies, potentially run native code.Source: vulncheck.com
Which versions are affected by CVE-2026-119756?
Tasmota: through 16.0.0.Source: cve.now feed data
Am I affected, and how do I check?
Tasmota through version 16.0.0 is affected when Device Groups receives UDP messages on port 4447. Native code execution specifically requires ESP8266 or ESP32 platforms that lack ASLR and heap cookies. Check your firmware version and whether Device Groups is enabled on the device.Source: vulncheck.com
How do I fix CVE-2026-119756?
Update to a build that includes commit e97e1e4, the fix named in the advisory. The facts do not name a release version that contains this commit.Source: vulncheck.com