{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-33774","assignerOrgId":"8cbe9d5a-a066-4c94-8978-4b15efeae968","state":"PUBLISHED","assignerShortName":"juniper","dateReserved":"2026-03-23T19:46:13.668Z","datePublished":"2026-04-09T21:34:21.126Z","dateUpdated":"2026-04-10T14:14:24.774Z"},"containers":{"cna":{"affected":[{"defaultStatus":"unaffected","platforms":["MX Series"],"product":"Junos OS","vendor":"Juniper Networks","versions":[{"lessThan":"23.2R2-S6","status":"affected","version":"0","versionType":"semver"},{"lessThan":"23.4R2-S7","status":"affected","version":"23.4","versionType":"semver"},{"lessThan":"24.2R2","status":"affected","version":"24.2","versionType":"semver"},{"lessThan":"24.4R2","status":"affected","version":"24.4","versionType":"semver"}]}],"datePublic":"2026-04-08T16:00:00.000Z","descriptions":[{"lang":"en","supportingMedia":[{"base64":false,"type":"text/html","value":"An Improper Check for Unusual or Exceptional Conditions vulnerability in the packet forwarding engine (pfe) of Juniper Networks Junos OS on MX Series allows an unauthenticated, network-based attacker to bypass the configured firewall filter and access the control-plane of the device.<br><br><span style=\"background-color: rgb(255, 255, 255);\">On MX platforms with \n\n<span style=\"background-color: rgb(255, 255, 255);\">MPC10, MPC11, LC4800 or LC9600</span>\n\nline cards, and MX304, firewall filters applied on a loopback interface lo0.n (where n is a non-0 number) don't get executed when lo0.n is in the global VRF / default routing-instance.<br><br> An affected configuration would be:<br></span><tt><span style=\"background-color: rgb(255, 255, 255);\"><br>user@host# show configuration interfaces lo0 | display set<br>set interfaces lo0 unit 1 family inet filter input &lt;filter-name&gt;</span></tt><span style=\"background-color: rgb(255, 255, 255);\"><br><br>where a firewall filter is applied to a non-0 loopback interface, but that loopback interface is not referred to in any routing-instance (RI) configuration, which implies that it's used in the default RI.<br><br>The issue can be observed with the CLI command:<br><br></span><tt><span style=\"background-color: rgb(255, 255, 255);\">user@device&gt; show firewall counter filter &lt;filter_name&gt;</span></tt> <br><br>not showing any matches.<br><br><p>This issue affects Junos OS on MX Series:</p><ul><li>all versions before 23.2R2-S6,</li><li>23.4 versions before 23.4R2-S7,</li><li>24.2 versions before 24.2R2,</li><li>24.4 versions before 24.4R2.</li></ul><p><br></p>"}],"value":"An Improper Check for Unusual or Exceptional Conditions vulnerability in the packet forwarding engine (pfe) of Juniper Networks Junos OS on MX Series allows an unauthenticated, network-based attacker to bypass the configured firewall filter and access the control-plane of the device.\n\nOn MX platforms with \n\nMPC10, MPC11, LC4800 or LC9600\n\nline cards, and MX304, firewall filters applied on a loopback interface lo0.n (where n is a non-0 number) don't get executed when lo0.n is in the global VRF / default routing-instance.\n\n An affected configuration would be:\n\nuser@host# show configuration interfaces lo0 | display set\nset interfaces lo0 unit 1 family inet filter input <filter-name>\n\nwhere a firewall filter is applied to a non-0 loopback interface, but that loopback interface is not referred to in any routing-instance (RI) configuration, which implies that it's used in the default RI.\n\nThe issue can be observed with the CLI command:\n\nuser@device> show firewall counter filter <filter_name> \n\nnot showing any matches.\n\nThis issue affects Junos OS on MX Series:\n\n  *  all versions before 23.2R2-S6,\n  *  23.4 versions before 23.4R2-S7,\n  *  24.2 versions before 24.2R2,\n  *  24.4 versions before 24.4R2."}],"exploits":[{"lang":"en","supportingMedia":[{"base64":false,"type":"text/html","value":"Juniper SIRT is not aware of any malicious exploitation of this vulnerability."}],"value":"Juniper SIRT is not aware of any malicious exploitation of this vulnerability."}],"metrics":[{"cvssV3_1":{"attackComplexity":"LOW","attackVector":"NETWORK","availabilityImpact":"NONE","baseScore":6.5,"baseSeverity":"MEDIUM","confidentialityImpact":"LOW","integrityImpact":"LOW","privilegesRequired":"NONE","scope":"UNCHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N","version":"3.1"},"format":"CVSS","scenarios":[{"lang":"en","value":"GENERAL"}]},{"cvssV4_0":{"Automatable":"YES","Recovery":"USER","Safety":"NOT_DEFINED","attackComplexity":"LOW","attackRequirements":"NONE","attackVector":"NETWORK","baseScore":6.9,"baseSeverity":"MEDIUM","privilegesRequired":"NONE","providerUrgency":"NOT_DEFINED","subAvailabilityImpact":"NONE","subConfidentialityImpact":"NONE","subIntegrityImpact":"NONE","userInteraction":"NONE","valueDensity":"NOT_DEFINED","vectorString":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N/AU:Y/R:U/RE:L","version":"4.0","vulnAvailabilityImpact":"NONE","vulnConfidentialityImpact":"LOW","vulnIntegrityImpact":"LOW","vulnerabilityResponseEffort":"LOW"},"format":"CVSS","scenarios":[{"lang":"en","value":"GENERAL"}]}],"problemTypes":[{"descriptions":[{"cweId":"CWE-754","description":"CWE-754 Improper Check for Unusual or Exceptional Conditions","lang":"en","type":"CWE"}]}],"providerMetadata":{"orgId":"8cbe9d5a-a066-4c94-8978-4b15efeae968","shortName":"juniper","dateUpdated":"2026-04-09T21:34:21.126Z"},"references":[{"tags":["vendor-advisory"],"url":"https://kb.juniper.net/JSA107865"}],"solutions":[{"lang":"en","supportingMedia":[{"base64":false,"type":"text/html","value":"The following software releases have been updated to resolve this specific issue: 23.2R2-S6, 23.4R2-S7, 24.2R2, 24.4R2, 25.2R1, and all subsequent releases."}],"value":"The following software releases have been updated to resolve this specific issue: 23.2R2-S6, 23.4R2-S7, 24.2R2, 24.4R2, 25.2R1, and all subsequent releases."}],"source":{"advisory":"JSA107865","defect":["1855648"],"discovery":"USER"},"title":"Junos OS: MX Series: Firewall filters on lo0.<non-0> in the default routing instance are not in effect","workarounds":[{"lang":"en","supportingMedia":[{"base64":false,"type":"text/html","value":"<span style=\"background-color: rgb(255, 255, 255);\">Renaming the lo0 logical unit used in the default routing instance from non-0 to 0 resolves this issue.</span><br>"}],"value":"Renaming the lo0 logical unit used in the default routing instance from non-0 to 0 resolves this issue."}],"x_generator":{"engine":"Vulnogram 0.1.0-dev"}},"adp":[{"metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-04-10T14:14:09.835711Z","id":"CVE-2026-33774","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"title":"CISA ADP Vulnrichment","providerMetadata":{"orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","shortName":"CISA-ADP","dateUpdated":"2026-04-10T14:14:24.774Z"}}]}}