CVE-2026-63362: o6 Automation open62541 Integer Underflow

Severity: medium (CVSS 5.9 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 1.8% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-07-30 · updated 2026-10-23
Weakness: CWE-191

Description

An unsigned integer underflow in the PubSub signature verification path in open62541 may allow a remote attacker to cause a denial of service via a crafted UDP packet.

Affected products

o6 Automation open62541: from 1.3.0 through 1.3.17; from 1.4.0 through 1.4.16; from 1.5.0 through 1.5.4; master

References

https://github.com/cisagov/CSAF/blob/develop/csaf_files/OT/white/2026/icsa-26-211-08.json
https://github.com/open62541/open62541/pull/8235/commits/b666d35769ce63998442e4d0810a3fb10b50179f
https://github.com/open62541/open62541/pull/8236/commits/06b99fef667c8ec5bdf0605b4f00c84fcc1d3a60
https://github.com/open62541/open62541/pull/8237/commits/1b71d9c5d9c4d02d4729b8903a52e9f530bf804e
https://github.com/open62541/open62541/pull/8238/commits/afab4107bfd161da9ce8bb30ed77f3968c9c97df
https://www.cisa.gov/news-events/ics-advisories/icsa-26-211-08
https://www.o6-automation.com/contact

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