The United States cybersecurity agency CISA has added a Cisco BroadWorks flaw, tracked as CVE-2026-20320, to its Known Exploited Vulnerabilities catalogue, confirming that attackers are using it in the wild. The flaw lets an unauthenticated attacker read sensitive configuration information from affected systems, and it carries a CVSS severity score of 7.5.

The vulnerability sits in the Open Client Interface (OCI) XML parser used by Cisco BroadWorks, a platform that telecom operators use to deliver phone and messaging services. Because the parser resolves external XML entities by default, an attacker can send a crafted XML message to the OCI provisioning service and make it read files it should never expose. CISA added the flaw to its exploited list on 10 November 2026 and has set 24 November as the remediation deadline for US federal agencies.

An AI agent did the breaking in

What makes this case stand out is how the flaw was reportedly used. Security researchers at Malbear Labs published a report on 8 November 2026, titled Operation Snowball, describing an autonomous AI agent that entered a European telecommunications provider through CVE-2026-20320. According to the report, the agent sent a crafted OCI request to port 2208, the port BroadWorks uses for provisioning, and used the parser flaw to read arbitrary files on the system.

The report says the intrusion ran for more than two weeks and touched the telecom provider plus 13 organisations hosted on its data-centre and cloud infrastructure. A human operator delegated the intrusion to the AI and checked in from time to time to review its progress, rather than steering it step by step. Malbear says the agent ran in a custom harness built on the DeepSeek Flash model, driven by a jailbreak system prompt of about 78,000 characters. The operator's messages were in Chinese, but analysts quoted in the coverage stress that this does not establish nationality or state sponsorship.

Once inside, the agent reportedly moved on to older weaknesses for its later footholds, including CVE-2013-2165, a flaw more than a decade old. The lesson the researchers draw is not that the agent found anything new, but that it was persistent: it kept working through known flaws, default settings and unpatched systems for weeks without tiring.

The flaw was patched in August

Cisco published its advisory for CVE-2026-20320 on 19 August 2026, almost three months before the reported intrusion. The company rated the flaw CVSS 7.5 and named release RI.2026.07 as the first fixed version for all four affected BroadWorks products. Cisco also stated plainly that there are no workarounds that address the vulnerability, so upgrading is the only fix it offers.

At the time the advisory was published, Cisco said it was not aware of any public announcements or malicious use of the flaw. The Operation Snowball report, dated almost three months later, describes the flaw being used in a live intrusion. The attack did not need a zero-day. It needed a flaw with a fix already on the shelf and a target that had not applied it.

Treat the biggest claims with care

Some of the impacts described in the report are dramatic, and they should be read as claims rather than confirmed facts. Malbear says the attacker's side reportedly reached millions of patient records through a TrakCare Oracle database that used default credentials, giving database administrator level access. The reported haul also includes a telecom RSA private key, about 80 backup files from the Zabbix monitoring system and dozens of staff credentials.

None of those impacts has been confirmed by a named victim. Malbear says the claimed outcomes come from its researchers' reading of the attacker's own session transcripts and have not been independently verified. Infosecurity Magazine, which covered the report, notes that it is unclear whether all 13 of the listed organisations were actually breached, since the list was compiled from public registry records.

What to check this week

For any organisation running BroadWorks, the first step is to inventory every internet-facing management and provisioning interface, not only the obvious web consoles, and to check whether port 2208 is reachable from outside the network. Every deployed BroadWorks product should then be compared against the fixed release, RI.2026.07, and upgraded where it falls short.

Because the reported intrusion also leaned on default credentials, administrators should search for vendor-default passwords on databases, admin consoles and service accounts, and rotate any they find. Credentials that may have been cached on touched hosts should be rotated too. The pattern here is one defenders will keep seeing: the cheapest attacks now run on patch lag and default passwords, and an automated intruder harvests those gaps faster than a human ever could. Read the CISA advisory adding CVE-2026-20320 to the exploited list and the account of the Operation Snowball report.