{"id":"CVE-2021-25677","aliases":["EUVD-2021-12569","GHSA-596h-hvjh-ffpf"],"status":"published","title":"A vulnerability has been identified in Nucleus 4 (All versions \u003c V4.1.0), Nucleus NET (All...","description":"A vulnerability has been identified in APOGEE PXC Compact (BACnet) (All versions \u003c V3.5.5), APOGEE PXC Compact (P2 Ethernet) (All versions \u003c V2.8.20), APOGEE PXC Modular (BACnet) (All versions \u003c V3.5.5), APOGEE PXC Modular (P2 Ethernet) (All versions \u003c V2.8.20), Nucleus NET (All versions), Nucleus ReadyStart V3 (All versions \u003c V2017.02.3), Nucleus ReadyStart V3 (All versions \u003c V2017.02.4), Nucleus ReadyStart V4 (All versions \u003c V4.1.0), Nucleus Source Code (Versions including affected DNS modules), SIMOTICS CONNECT 400 (All versions \u003c V0.5.0.0), SIMOTICS CONNECT 400 (All versions \u003e= V0.5.0.0 \u003c V1.0.0.0), TALON TC Compact (BACnet) (All versions \u003c V3.5.5), TALON TC Modular (BACnet) (All versions \u003c V3.5.5). The DNS client does not properly randomize DNS transaction IDs. That could allow an attacker to poison the DNS cache or spoof DNS resolving.","severity":{"version":"3.1","score":5.3,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N/E:P/RL:O/RC:C","level":"medium","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-11","score":0.01177,"percentile":0.67997,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":false},"cwes":["CWE-330"],"published":"2021-04-22T20:42:21Z","modified":"2026-06-17T03:42:20Z","products":[{"vendor":"siemens","product":"apogee pxc compact (bacnet)"},{"vendor":"siemens","product":"apogee pxc compact (p2 ethernet)"},{"vendor":"siemens","product":"apogee pxc modular (bacnet)"},{"vendor":"siemens","product":"apogee pxc modular (p2 ethernet)"},{"vendor":"siemens","product":"nucleus net"},{"vendor":"siemens","product":"nucleus readystart v3"},{"vendor":"siemens","product":"nucleus readystart v4"},{"vendor":"siemens","product":"nucleus source code"},{"vendor":"siemens","product":"nucleus_net"},{"vendor":"siemens","product":"nucleus_readystart_v3"},{"vendor":"siemens","product":"nucleus_readystart_v4"},{"vendor":"siemens","product":"nucleus_source_code"},{"vendor":"siemens","product":"simotics connect 400"},{"vendor":"siemens","product":"simotics_connect_400_firmware"},{"vendor":"siemens","product":"talon tc compact (bacnet)"},{"vendor":"siemens","product":"talon tc modular (bacnet)"}],"references":[{"url":"https://cert-portal.siemens.com/productcert/pdf/ssa-705111.pdf","tags":["x_transferred","Patch","Vendor Advisory"]},{"url":"https://cert-portal.siemens.com/productcert/pdf/ssa-669158.pdf","tags":["x_transferred","Patch","Vendor Advisory"]},{"url":"https://cert-portal.siemens.com/productcert/pdf/ssa-180579.pdf","tags":["x_transferred"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2021-25677"},{"url":"https://github.com/advisories/GHSA-596h-hvjh-ffpf"}],"sources":{"cve":[{"id":"CVE-2021-25677","description":"A vulnerability has been identified in APOGEE PXC Compact (BACnet) (All versions \u003c V3.5.5), APOGEE PXC Compact (P2 Ethernet) (All versions \u003c V2.8.20), APOGEE PXC Modular (BACnet) (All versions \u003c V3.5.5), APOGEE PXC Modular (P2 Ethernet) (All versions \u003c V2.8.20), Nucleus NET (All versions), Nucleus ReadyStart V3 (All versions \u003c V2017.02.3), Nucleus ReadyStart V3 (All versions \u003c V2017.02.4), Nucleus ReadyStart V4 (All versions \u003c V4.1.0), Nucleus Source Code (Versions including affected DNS modules), SIMOTICS CONNECT 400 (All versions \u003c V0.5.0.0), SIMOTICS CONNECT 400 (All versions \u003e= V0.5.0.0 \u003c V1.0.0.0), TALON TC Compact (BACnet) (All versions \u003c V3.5.5), TALON TC Modular (BACnet) (All versions \u003c V3.5.5). The DNS client does not properly randomize DNS transaction IDs. That could allow an attacker to poison the DNS cache or spoof DNS resolving.","status":"published","published":"2021-04-22T20:42:21Z","modified":"2024-08-03T20:11:28.339Z","cvss":[{"version":"3.1","score":5.3,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N/E:P/RL:O/RC:C","level":"medium","assessor":"cna"}],"cwes":["CWE-330"],"updated_at":"2026-11-02T14:32:59.430294Z"}],"euvd":[{"id":"EUVD-2021-12569","description":"A vulnerability has been identified in APOGEE PXC Compact (BACnet) (All versions \u003c V3.5.5), APOGEE PXC Compact (P2 Ethernet) (All versions \u003c V2.8.20), APOGEE PXC Modular (BACnet) (All versions \u003c V3.5.5), APOGEE PXC Modular (P2 Ethernet) (All versions \u003c V2.8.20), Nucleus NET (All versions), Nucleus ReadyStart V3 (All versions \u003c V2017.02.3), Nucleus ReadyStart V3 (All versions \u003c V2017.02.4), Nucleus ReadyStart V4 (All versions \u003c V4.1.0), Nucleus Source Code (Versions including affected DNS modules), SIMOTICS CONNECT 400 (All versions \u003c V0.5.0.0), SIMOTICS CONNECT 400 (All versions \u003e= V0.5.0.0 \u003c V1.0.0.0), TALON TC Compact (BACnet) (All versions \u003c V3.5.5), TALON TC Modular (BACnet) (All versions \u003c V3.5.5). The DNS client does not properly randomize DNS transaction IDs. That could allow an attacker to poison the DNS cache or spoof DNS resolving.","status":"published","published":"2021-04-22T20:42:21Z","modified":"2024-08-03T20:11:28Z","cvss":[{"version":"3.1","score":5.3,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N/E:P/RL:O/RC:C","level":"medium"}],"updated_at":"2026-11-03T03:24:52.420769Z"}],"ghsa":[{"id":"GHSA-596h-hvjh-ffpf","title":"A vulnerability has been identified in Nucleus 4 (All versions \u003c V4.1.0), Nucleus NET (All...","description":"A vulnerability has been identified in Nucleus 4 (All versions \u003c V4.1.0), Nucleus NET (All versions), Nucleus RTOS (versions including affected DNS modules), Nucleus ReadyStart (All versions \u003c V2017.02.3), Nucleus Source Code (versions including affected DNS modules), SIMOTICS CONNECT 400 (All versions \u003c V0.5.0.0), SIMOTICS CONNECT 400 (All versions \u003e= V0.5.0.0), VSTAR (versions including affected DNS modules). The DNS client does not properly randomize DNS transaction IDs. That could allow an attacker to poison the DNS cache or spoof DNS resolving.","status":"published","published":"2022-05-24T17:48:17Z","modified":"2023-08-17T05:01:45Z","cvss":[{"version":"3.1","score":5.3,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N","level":"medium"}],"cwes":["CWE-330"],"updated_at":"2026-11-02T14:54:45.250925Z"}],"nvd":[{"id":"CVE-2021-25677","description":"A vulnerability has been identified in APOGEE PXC Compact (BACnet) (All versions \u003c V3.5.5), APOGEE PXC Compact (P2 Ethernet) (All versions \u003c V2.8.20), APOGEE PXC Modular (BACnet) (All versions \u003c V3.5.5), APOGEE PXC Modular (P2 Ethernet) (All versions \u003c V2.8.20), Nucleus NET (All versions), Nucleus ReadyStart V3 (All versions \u003c V2017.02.3), Nucleus ReadyStart V3 (All versions \u003c V2017.02.4), Nucleus ReadyStart V4 (All versions \u003c V4.1.0), Nucleus Source Code (Versions including affected DNS modules), SIMOTICS CONNECT 400 (All versions \u003c V0.5.0.0), SIMOTICS CONNECT 400 (All versions \u003e= V0.5.0.0 \u003c V1.0.0.0), TALON TC Compact (BACnet) (All versions \u003c V3.5.5), TALON TC Modular (BACnet) (All versions \u003c V3.5.5). The DNS client does not properly randomize DNS transaction IDs. That could allow an attacker to poison the DNS cache or spoof DNS resolving.","status":"published","published":"2021-04-22T21:15:10.207Z","modified":"2026-06-17T03:42:20.547Z","cvss":[{"version":"3.1","score":5.3,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N","level":"medium","assessor":"secondary"},{"version":"3.1","score":5.3,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N","level":"medium","assessor":"primary"},{"version":"2.0","score":5,"vector":"AV:N/AC:L/Au:N/C:N/I:P/A:N","level":"medium","assessor":"primary"}],"cwes":["CWE-330"],"updated_at":"2026-11-02T14:06:52.03307Z"}]}}