CVE-2020-13364

Name of the Vulnerable Software and Affected Versions Zyxel NAS520 versions V5.11(AASZ.0)C0 through V5.21(AASZ.4)C0 Zyxel NAS542 versions V5.11(ABAG.0)C0 through V5.21(ABAG.3)C0 Zyxel NSA325 versions V4.81(AAAJ.1)C0 and V4.81(AALS.0)C0 Zyxel NSA310 versions 4.22(AFK.0)C0 and 4.22(AFK.1)C0 Zyxel NAS326 versions V5.11(AAZF.2)C0 through V5.21(AAZF.8)C0 Zyxel NSA310S version V4.75(AALH.2)C0 Zyxel NSA320S versions V4.75(AANV.1)C0 and V4.75(AANV.2)C0 Zyxel NSA221 version V4.41(AFM.1)C0 Zyxel NAS540 versions V5.21(AATB.3)C0 and V5.21(AATB.5)C0

Description A backdoor in certain Zyxel products allows remote TELNET access via a CGI script.

Recommendations For NAS520 versions V5.11(AASZ.0)C0 through V5.21(AASZ.4)C0, consider disabling the TELNET access until a patch is available. For NAS542 versions V5.11(ABAG.0)C0 through V5.21(ABAG.3)C0, restrict access to the CGI script to minimize the risk of exploitation. For NSA325 versions V4.81(AAAJ.1)C0 and V4.81(AALS.0)C0, avoid using the remote access feature until the issue is resolved. For NSA310 versions 4.22(AFK.0)C0 and 4.22(AFK.1)C0, consider disabling the remote access feature as a temporary workaround. For NAS326 versions V5.11(AAZF.2)C0 through V5.21(AAZF.8)C0, restrict access to the vulnerable CGI script. For NSA310S version V4.75(AALH.2)C0, consider disabling the TELNET access until a patch is available. For NSA320S versions V4.75(AANV.1)C0 and V4.75(AANV.2)C0, avoid using the remote access feature until the issue is resolved. For NSA221 version V4.41(AFM.1)C0, restrict access to the CGI script to minimize the risk of exploitation. For NAS540 versions V5.21(AATB.3)C0 and V5.21(AATB.5)C0, consider disabling the TELNET access until a patch is available.