{"id":"CVE-2021-22901","url":"https://www.cyber-defence.io/tools/cve/CVE-2021-22901","generatedAt":"2026-11-05T01:17:37.788Z","title":"curl 7.75.0 through 7.76.1 suffers from a use-after-free vulnerability resulting in already freed memory being used when a TLS 1.3 session ticket arrives over a connection.","description":"curl 7.75.0 through 7.76.1 suffers from a use-after-free vulnerability resulting in already freed memory being used when a TLS 1.3 session ticket arrives over a connection. A malicious server can use this in rare unfortunate circumstances to potentially reach remote code execution in the client. When libcurl at run-time sets up support for TLS 1.3 session tickets on a connection using OpenSSL, it stores pointers to the transfer in-memory object for later retrieval when a session ticket arrives. If the connection is used by multiple transfers (like with a reused HTTP/1.1 connection or multiplexed HTTP/2 connection) that first transfer object might be freed before the new session is established on that connection and then the function will access a memory buffer that might be freed. When using that memory, libcurl might even call a function pointer in the object, making it possible for a remote code execution if the server could somehow manage to get crafted memory content into the correct place in memory.","published":"2021-06-11T16:15:11.000Z","lastModified":"2026-10-14T11:16:53.000Z","status":"Modified","sourceIdentifier":"support@hackerone.com","cvss":{"version":"3.1","score":8.1,"severity":"HIGH","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H"},"cwe":["CWE-416"],"affected":["haxx/curl","oracle/communications cloud native core binding support function","oracle/communications cloud native core network function cloud native environment","oracle/communications cloud native core network repository function","oracle/communications cloud native core network slice selection function","oracle/communications cloud native core service communication proxy","oracle/essbase","oracle/mysql server","netapp/active iq unified manager","netapp/cloud backup","netapp/oncommand insight","netapp/oncommand workflow automation","netapp/snapcenter","netapp/solidfire\\, enterprise sds \\& hci storage node","netapp/solidfire \\& hci management node","netapp/solidfire baseboard management controller firmware","netapp/hci compute node firmware","netapp/h300e firmware","netapp/h300s firmware","netapp/h410s firmware","netapp/h500e firmware","netapp/h500s firmware","netapp/h700e firmware","netapp/h700s firmware","siemens/sinec infrastructure network services","splunk/universal forwarder"],"epss":{"score":0.63531,"percentile":0.99213,"date":"2026-11-03","history":[{"date":"2026-10-15","score":0.63531,"percentile":0.99205}]},"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 63.5%, higher than 99% of all known CVEs. Patch or mitigate before the next change window."},"changes":[],"references":[{"url":"https://cert-portal.siemens.com/productcert/pdf/ssa-389290.pdf","tags":["Patch","Third Party Advisory"],"source":"support@hackerone.com"},{"url":"https://cert-portal.siemens.com/productcert/pdf/ssa-732250.pdf","tags":["Third Party Advisory"],"source":"support@hackerone.com"},{"url":"https://curl.se/docs/CVE-2021-22901.html","tags":["Exploit","Patch","Vendor Advisory"],"source":"support@hackerone.com"},{"url":"https://github.com/curl/curl/commit/7f4a9a9b2a49547eae24d2e19bc5c346e9026479","tags":["Patch","Third Party Advisory"],"source":"support@hackerone.com"},{"url":"https://hackerone.com/reports/1180380","tags":["Exploit","Issue Tracking","Third Party Advisory"],"source":"support@hackerone.com"},{"url":"https://security.netapp.com/advisory/ntap-20210723-0001/","tags":["Third Party Advisory"],"source":"support@hackerone.com"},{"url":"https://security.netapp.com/advisory/ntap-20210727-0007/","tags":["Third Party Advisory"],"source":"support@hackerone.com"},{"url":"https://www.oracle.com//security-alerts/cpujul2021.html","tags":["Patch","Third Party Advisory"],"source":"support@hackerone.com"},{"url":"https://www.oracle.com/security-alerts/cpuapr2022.html","tags":["Patch","Third Party Advisory"],"source":"support@hackerone.com"},{"url":"https://www.oracle.com/security-alerts/cpujan2022.html","tags":["Patch","Third Party Advisory"],"source":"support@hackerone.com"},{"url":"https://cert-portal.siemens.com/productcert/pdf/ssa-389290.pdf","tags":["Patch","Third Party Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://cert-portal.siemens.com/productcert/pdf/ssa-732250.pdf","tags":["Third Party Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://curl.se/docs/CVE-2021-22901.html","tags":["Exploit","Patch","Vendor Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://github.com/curl/curl/commit/7f4a9a9b2a49547eae24d2e19bc5c346e9026479","tags":["Patch","Third Party Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://hackerone.com/reports/1180380","tags":["Exploit","Issue Tracking","Third Party Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://security.netapp.com/advisory/ntap-20210723-0001/","tags":["Third Party Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://security.netapp.com/advisory/ntap-20210727-0007/","tags":["Third Party Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://www.oracle.com//security-alerts/cpujul2021.html","tags":["Patch","Third Party Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://www.oracle.com/security-alerts/cpuapr2022.html","tags":["Patch","Third Party Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://www.oracle.com/security-alerts/cpujan2022.html","tags":["Patch","Third Party Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://cert-portal.siemens.com/productcert/html/ssa-389290.html","source":"0b142b55-0307-4c5a-b3c9-f314f3fb7c5e"},{"url":"https://cert-portal.siemens.com/productcert/html/ssa-398330.html","source":"0b142b55-0307-4c5a-b3c9-f314f3fb7c5e"},{"url":"https://cert-portal.siemens.com/productcert/html/ssa-732250.html","source":"0b142b55-0307-4c5a-b3c9-f314f3fb7c5e"}],"sources":{"nvd":"https://nvd.nist.gov/vuln/detail/CVE-2021-22901","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."}