CVE-2026-63201

Description

Netopeer2 is a server for implementing network configuration management based on the `NETCONF` Protocol. In affected versions, a low-privileged authenticated `NETCONF` user can remotely crash `netopeer2-server` by sending a `get RPC` with an invalid `subtree filter` whose text contains format specifiers. In `src/netconf.c`, `np2srv_rpc_get_cb()` sends the invalid value through `ERR()` to `np2log_printf()`, where `vsnprintf()` first formats the message safely. In `src/log.c`, that already formatted buffer is subsequently passed to `np2log()` as the format string itself, causing `vsyslog()` to interpret attacker-controlled percent sequences and read invalid pointer arguments. The reported denial of service was confirmed on version 2.8.7 using `NETCONF`-over-SSH and AddressSanitizer; reliable remote code execution was not confirmed. `The advisory identifies 2.8.8 as patched`; repository comparisons verify the fix in public release 2.8.21. The affected/fixed boundary remains unresolved because no public 2.8.8 tag was located, which does not establish the status of an untagged 2.8.8 build.

Is your site exposed to CVE-2026-63201?

Run a free security scan — no signup, results in seconds.

Weakness Type (CWE)

CWE-134 CWE-134

References

Other References

https://github.com/CESNET/netopeer2/commit/e98beb2d4d8cc82875208bccb8e1348a8e9e95b3 https://github.com/CESNET/netopeer2/releases/tag/2.8.21 https://github.com/CESNET/netopeer2/security/advisories/GHSA-25gm-4x89-7r2q

Frequently Asked Questions

What is CVE-2026-63201? +

Netopeer2 is a server for implementing network configuration management based on the `NETCONF` Protocol. In affected versions, a low-privileged authenticated `NETCONF` user can remotely crash `netopeer2-server` by sending a `get RPC` with an invalid `subtree filter` whose text contains format specifiers. In `src/netconf.c`, `np2srv_rpc_get_cb()` sends the invalid value through `ERR()` to `np2log_printf()`, where `vsnprintf()` first formats the message safely. In `src/log.c`, that already formatted buffer is subsequently passed to `np2log()` as the format string itself, causing `vsyslog()` to interpret attacker-controlled percent sequences and read invalid pointer arguments. The reported denial of service was confirmed on version 2.8.7 using `NETCONF`-over-SSH and AddressSanitizer; reliable remote code execution was not confirmed. `The advisory identifies 2.8.8 as patched`; repository comparisons verify the fix in public release 2.8.21. The affected/fixed boundary remains unresolved because no public 2.8.8 tag was located, which does not establish the status of an untagged 2.8.8 build.

How do I check if I'm vulnerable to CVE-2026-63201? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

Related Vulnerabilities

CVE-2024-9129

In versions of Zend Server 8.5 and prior to version 9.2 a format string injection was discovered. Reported by Dylan …

CVE-2010-10017

WM Downloader version 3.1.2.2 is vulnerable to a buffer overflow when processing a specially crafted .m3u playlist file. The application …

CVE-2012-10055

ComSndFTP FTP Server version 1.3.7 Beta contains a format string vulnerability in its handling of the USER command. By sending …

CVE-2026-6241

An authenticated format string vulnerability is present in the ONVIF AddScopes in Tapo C520WS v2, where user-controlled input is improperly …

CVE-2011-10029

Solar FTP Server fails to properly handle format strings passed to the USER command. When a specially crafted string containing …

CVE-2026-18461

Use of Externally-Controlled Format String vulnerability in RTI Connext Professional (Core Libraries) allows Format String Injection. This issue affects Connext …