{"id":"CVE-2026-63201","state":"PUBLISHED","title":"netopeer2-server logging has format string vulnerability via subtree filter","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.","publishedAt":"2026-10-30T22:03:18.551Z","updatedAt":"2026-10-30T22:03:18.551Z","severity":{"score":7.1,"label":"High","version":"4.0","vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N","source":"GitHub_M"},"assigner":"GitHub_M","products":["CESNET netopeer2"],"affected":[{"vendor":"CESNET","product":"netopeer2","versions":[{"version":"< 2.8.21","status":"affected"}]}],"references":["https://github.com/CESNET/netopeer2/security/advisories/GHSA-25gm-4x89-7r2q","https://github.com/CESNET/netopeer2/commit/e98beb2d4d8cc82875208bccb8e1348a8e9e95b3","https://github.com/CESNET/netopeer2/releases/tag/2.8.21"],"weaknesses":["CWE-134"],"ingestedAt":"2026-10-30T22:16:06.501Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/63xxx/CVE-2026-63201.json","commit":"226652b7321cd45ef01add6f464a8114b52515e5","baselineCommit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-63201","state":"PUBLISHED","datePublished":"2026-10-30T22:03:18.551Z","dateUpdated":"2026-10-30T22:03:18.551Z","assignerShortName":"GitHub_M","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateReserved":"2026-07-15T22:19:06.905Z"},"containers":{"cna":{"title":"netopeer2-server logging has format string vulnerability via subtree filter","descriptions":[{"lang":"en","value":"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."}],"affected":[{"vendor":"CESNET","product":"netopeer2","versions":[{"version":"< 2.8.21","status":"affected"}]}],"references":[{"url":"https://github.com/CESNET/netopeer2/security/advisories/GHSA-25gm-4x89-7r2q","name":"https://github.com/CESNET/netopeer2/security/advisories/GHSA-25gm-4x89-7r2q","tags":["x_refsource_CONFIRM"]},{"url":"https://github.com/CESNET/netopeer2/commit/e98beb2d4d8cc82875208bccb8e1348a8e9e95b3","name":"https://github.com/CESNET/netopeer2/commit/e98beb2d4d8cc82875208bccb8e1348a8e9e95b3","tags":["x_refsource_MISC"]},{"url":"https://github.com/CESNET/netopeer2/releases/tag/2.8.21","name":"https://github.com/CESNET/netopeer2/releases/tag/2.8.21","tags":["x_refsource_MISC"]}],"metrics":[{"cvssV4_0":{"attackVector":"NETWORK","attackComplexity":"LOW","attackRequirements":"NONE","privilegesRequired":"LOW","userInteraction":"NONE","vulnConfidentialityImpact":"NONE","vulnIntegrityImpact":"NONE","vulnAvailabilityImpact":"HIGH","subConfidentialityImpact":"NONE","subIntegrityImpact":"NONE","subAvailabilityImpact":"NONE","baseScore":7.1,"baseSeverity":"HIGH","vectorString":"CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N","version":"4.0"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-134","lang":"en","description":"CWE-134: Use of Externally-Controlled Format String","type":"CWE"}]}],"providerMetadata":{"shortName":"GitHub_M","orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateUpdated":"2026-10-30T22:03:18.551Z"},"source":{"advisory":"GHSA-25gm-4x89-7r2q","discovery":"UNKNOWN"}}}}}