{"id":"CVE-2021-43557","url":"https://www.cyber-defence.io/tools/cve/CVE-2021-43557","generatedAt":"2026-11-05T00:59:08.067Z","title":"This makes it possible to construct a URI to bypass the block list on some occasions.","description":"The uri-block plugin in Apache APISIX before 2.10.2 uses $request_uri without verification. The $request_uri is the full original request URI without normalization. This makes it possible to construct a URI to bypass the block list on some occasions. For instance, when the block list contains \"^/internal/\", a URI like `//internal/` can be used to bypass it. Some other plugins also have the same issue. And it may affect the developer's custom plugin.","published":"2021-11-22T09:15:08.000Z","lastModified":"2026-06-17T04:11:08.000Z","status":"Modified","sourceIdentifier":"security@apache.org","cvss":{"version":"3.1","score":7.5,"severity":"HIGH","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N"},"cwe":["CWE-77"],"affected":["apache/apisix"],"epss":{"score":0.13044,"percentile":0.96348,"date":"2026-11-03","history":[]},"kev":{"listed":false},"exploits":{"count":0,"verified":false,"firstPublished":null,"source":"Exploit-DB (https://gitlab.com/exploit-database/exploitdb)","entries":[]},"verdict":{"level":"urgent","text":"EPSS puts the probability of exploitation in the next 30 days at 13.0%, higher than 96% of all known CVEs. Patch or mitigate before the next change window."},"changes":[],"references":[{"url":"http://www.openwall.com/lists/oss-security/2021/11/22/1","tags":["Mailing List","Third Party Advisory"],"source":"security@apache.org"},{"url":"http://www.openwall.com/lists/oss-security/2021/11/22/2","tags":["Mailing List","Third Party Advisory"],"source":"security@apache.org"},{"url":"http://www.openwall.com/lists/oss-security/2021/11/23/1","tags":["Exploit","Mailing List","Third Party Advisory"],"source":"security@apache.org"},{"url":"https://lists.apache.org/thread/18jyd458ptocr31rnkjs71w4h366mv7h","tags":["Exploit","Mailing List","Vendor Advisory"],"source":"security@apache.org"},{"url":"http://www.openwall.com/lists/oss-security/2021/11/22/1","tags":["Mailing List","Third Party Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"http://www.openwall.com/lists/oss-security/2021/11/22/2","tags":["Mailing List","Third Party Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"http://www.openwall.com/lists/oss-security/2021/11/23/1","tags":["Exploit","Mailing List","Third Party Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://lists.apache.org/thread/18jyd458ptocr31rnkjs71w4h366mv7h","tags":["Exploit","Mailing List","Vendor Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"}],"sources":{"nvd":"https://nvd.nist.gov/vuln/detail/CVE-2021-43557","epss":"https://www.first.org/epss/","kev":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog","exploitdb":"https://www.exploit-db.com/"},"licence":"CC BY 4.0 — link back to the CVE Explorer if you publish the results; upstream data remains subject to its own terms."}