CVE-2026-1301: o6 Automation Open62541 · Out-of-bounds Write
Affects o6 Automation Open62541Source CVE Database V5
Not known to be exploited · CVSS 6.8 Medium : upgrade to 1.5-rc2 when convenient.
Data as of 25 Oct 2026, 19:02 UTC
- EPSS
- 0.3% chance of exploitation in 30 days – higher than 32% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 1.5-rc2
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:A/VC:N/VI:N/VA:H/SC:N/SI:N/SA:NExploitation evidence
Disclosed: evidence found.
CVE published 5 Feb 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 2026-10-25.
What to do
Upgrade o6 Automation Open62541 to 1.5-rc2.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| o6 Automation GmbHOpen62541 | Affected
| Fixed in
|
AI-suggested
If you cannot patch yet, it is critical to disable PubSub and JSON encoding features if not strictly necessary or to implement strict input validation and filtering on JSON messages at network boundaries. Network segmentation should be enforced to isolate OPC UA communication channels from untrusted networks and limit exposure to potential attackers. Deploying intrusion detection systems with signatures for anomalous JSON payloads targeting OPC UA may help detect exploitation attempts. Additionally, enforcing strict authentication and authorization policies on OPC UA servers, even though this vulnerability occurs pre-authentication, can reduce overall attack surface. Regular security audits and penetration testing focused on industrial protocols should be conducted to identify and remediate similar risks.
Description
In builds with PubSub and JSON enabled, a crafted JSON message can cause the decoder to write beyond a heap-allocated array before authentication, reliably crashing the process and corrupting memory.