Is CVE-2026-63201 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-63201 being exploited in the wild.

How severe is CVE-2026-63201?

Informational severity, published 30 October 2026.

Which products and versions are affected?

CESNET Netopeer2 before 2.8.21.

Is there a fix for CVE-2026-63201?

Yes: fixed in 2.8.21. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

How is CVE-2026-63201 attacked?

It is attacked over the network, in a hosted service.

Am I affected by CVE-2026-63201?

Check whether you run CESNET Netopeer2 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.

CVE-2026-63201: Netopeer2 format string vulnerability in RPC handling

CVE-2026-63201 · Severity: info · Published 2026-10-30

Netopeer2 is a server that manages network device configuration via the NETCONF protocol. An authenticated attacker can crash the Netopeer2 server by sending a specially crafted network configuration request containing format string sequences, disrupting network management operations. While denial of service was confirmed, reliable remote code execution was not demonstrated.

Vendors: CESNET.

Quick answers

Is CVE-2026-63201 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-63201 being exploited in the wild.
How severe is CVE-2026-63201?: Informational severity, published 30 October 2026.
Which products and versions are affected?: CESNET Netopeer2 before 2.8.21.
Is there a fix for CVE-2026-63201?: Yes: fixed in 2.8.21. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-63201 attacked?: It is attacked over the network, in a hosted service.
Am I affected by CVE-2026-63201?: Check whether you run CESNET Netopeer2 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.

How to fix

Fixed in: 2.8.21

Technical details

A format string vulnerability exists in src/log.c where error messages containing attacker-controlled subtree filter data are passed directly as format strings to vsyslog(), allowing an authenticated NETCONF user to read invalid memory. The vulnerability requires prior NETCONF authentication and occurs when sending a get RPC with an invalid subtree filter; the fix changes the logging call to use "%s" format specifier.

Affected products

CESNET Netopeer2 before 2.8.21

Timeline

2026-10-30: disclosed
2026-10-14: patched: Public release 2.8.21 confirmed containing the fix

References

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