{"attribution":"This product uses data from the NVD API but is not endorsed or certified by the NVD.","cve":{"id":"CVE-2021-28543","sourceIdentifier":"cve@mitre.org","published":"2021-03-16T15:15:13.843","lastModified":"2026-06-17T03:46:30.047","vulnStatus":"Modified","cveTags":[],"descriptions":[{"lang":"en","value":"Varnish varnish-modules before 0.17.1 allows remote attackers to cause a denial of service (daemon restart) in some configurations. This does not affect organizations that only install the Varnish Cache product; however, it is common to install both Varnish Cache and varnish-modules. Specifically, an assertion failure or NULL pointer dereference can be triggered in Varnish Cache through the varnish-modules header.append() and header.copy() functions. For some Varnish Configuration Language (VCL) files, this gives remote clients an opportunity to cause a Varnish Cache restart. A restart reduces overall availability and performance due to an increased number of cache misses, and may cause higher load on backend servers."},{"lang":"es","value":"Varnish varnish-modules versiones anteriores a 0.17.1, permite a atacantes remotos causar una denegación de servicio (reinicio del demonio) en algunas configuraciones.\u0026#xa0;Esto no afecta a organizaciones que solo instalan el producto Varnish Cache;\u0026#xa0;sin embargo, es común instalar tanto Varnish Cache como varnish-modules.\u0026#xa0;Específicamente, un error de aserción o desreferencia del puntero NULL se puede activar en Varnish Cache por medio de las funciones header.append() y header.copy() de varnish-modules.\u0026#xa0;Para algunos archivos de Varnish Configuration Language (VCL), esto brinda a clientes remotos la oportunidad de causar un reinicio de Varnish Cache.\u0026#xa0;Un reinicio reduce la disponibilidad y el rendimiento general debido a un mayor número de pérdidas de caché y puede causar una mayor carga en los servidores de backend"}],"affected":[{"source":"cve@mitre.org","affectedData":[{"vendor":"n/a","product":"n/a","versions":[{"version":"n/a","status":"affected"}]}]}],"metrics":{"cvssMetricV31":[{"source":"cve@mitre.org","type":"Secondary","cvssData":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:N/A:L","baseScore":4.0,"baseSeverity":"MEDIUM","attackVector":"NETWORK","attackComplexity":"HIGH","privilegesRequired":"NONE","userInteraction":"NONE","scope":"CHANGED","confidentialityImpact":"NONE","integrityImpact":"NONE","availabilityImpact":"LOW"},"exploitabilityScore":2.2,"impactScore":1.4},{"source":"nvd@nist.gov","type":"Primary","cvssData":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","baseScore":7.5,"baseSeverity":"HIGH","attackVector":"NETWORK","attackComplexity":"LOW","privilegesRequired":"NONE","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"NONE","integrityImpact":"NONE","availabilityImpact":"HIGH"},"exploitabilityScore":3.9,"impactScore":3.6}],"cvssMetricV2":[{"source":"nvd@nist.gov","type":"Primary","cvssData":{"version":"2.0","vectorString":"AV:N/AC:L/Au:N/C:N/I:N/A:P","baseScore":5.0,"accessVector":"NETWORK","accessComplexity":"LOW","authentication":"NONE","confidentialityImpact":"NONE","integrityImpact":"NONE","availabilityImpact":"PARTIAL"},"baseSeverity":"MEDIUM","exploitabilityScore":10.0,"impactScore":2.9,"acInsufInfo":false,"obtainAllPrivilege":false,"obtainUserPrivilege":false,"obtainOtherPrivilege":false,"userInteractionRequired":false}]},"weaknesses":[{"source":"nvd@nist.gov","type":"Primary","description":[{"lang":"en","value":"CWE-476"},{"lang":"en","value":"CWE-617"}]}],"configurations":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:a:varnish-cache:varnish-modules:*:*:*:*:*:*:*:*","versionEndExcluding":"0.17.1","matchCriteriaId":"7EF31F4C-6C1C-4774-9D64-C288CB059C15"},{"vulnerable":true,"criteria":"cpe:2.3:a:varnish-cache:varnish-modules_klarlack:*:*:*:*:*:*:*:*","versionEndExcluding":"0.17.1","matchCriteriaId":"6E98D45B-7CBC-432F-B40E-DC9C67B07667"}]}]},{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:fedoraproject:fedora:34:*:*:*:*:*:*:*","matchCriteriaId":"A930E247-0B43-43CB-98FF-6CE7B8189835"}]}]}],"references":[{"url":"https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/OPFBRQUJNWHCB3GQHSSAPRLQU6Q6PY43/","source":"cve@mitre.org"},{"url":"https://varnish-cache.org/security/VSV00006.html","source":"cve@mitre.org","tags":["Vendor Advisory"]},{"url":"https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/OPFBRQUJNWHCB3GQHSSAPRLQU6Q6PY43/","source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://varnish-cache.org/security/VSV00006.html","source":"af854a3a-2127-422b-91ae-364da2661108","tags":["Vendor Advisory"]}]}}