Reference page — cumulative record through Monday, October 19, 2026 UTC. Reference pages update as the archive grows; only dated daily editions are immutable pages of record.

CVE-2021-22901

CVE-2021-22901HIGH

n/a https://github.com/curl/curl — 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 sessio…

  AV  AC  PR  UI  S  C  I  A   CVSS    EPSS   %ile   KEV
   N   H   N   N  U  H  H  H    8.1   .6353   99.2     —

AFFECTED
  Product                       Versions                 Fixed
  https://github.com/curl/curl  7.75.0 through 7.76.1 –  —

TIMELINE
  Jan 6   Reserved by hackerone
  Jun 11  Published (CNA: hackerone)
  Oct 8   ENRICHED — CVE-2021-22901 (https://github.com/curl/curl). Received CVSS 8.1 and CPE data from NVD.
  Oct 8   EXPLOIT PUBLISHED — CVE-2021-22901 (https://github.com/curl/curl). Public exploit reference added.
  Oct 14  EXPLOIT PUBLISHED — CVE-2021-22901 (https://github.com/curl/curl). Public exploit reference added.

CWE-416 · CNA: hackerone · CVSS v3.1 · 13 references · NVD status: Modified

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.

Lifecycle

Complete event history — 5 events, chronological
Date	Event	Detail
January 6, 2021	Reserved	Reserved by hackerone
June 11, 2021	Published	Published (CNA: hackerone)
October 8, 2026	ENRICHED	ENRICHED — CVE-2021-22901 (https://github.com/curl/curl). Received CVSS 8.1 and CPE data from NVD.
October 8, 2026	EXPLOIT PUBLISHED	EXPLOIT PUBLISHED — CVE-2021-22901 (https://github.com/curl/curl). Public exploit reference added.
October 14, 2026	EXPLOIT PUBLISHED	EXPLOIT PUBLISHED — CVE-2021-22901 (https://github.com/curl/curl). Public exploit reference added.

Affected

Affected products and packages — 1 row
Vendor	Product / Package	Ecosystem	Version introduced	Fixed
n/a	https://github.com/curl/curl	—	7.75.0 through 7.76.1	—

Weaknesses

CWE-416

References (13)

https://cert-portal.siemens.com/productcert/html/ssa-389290.html
https://cert-portal.siemens.com/productcert/html/ssa-398330.html
https://cert-portal.siemens.com/productcert/html/ssa-732250.html
https://cert-portal.siemens.com/productcert/pdf/ssa-389290.pdf [Patch, Third Party Advisory]
https://cert-portal.siemens.com/productcert/pdf/ssa-732250.pdf [Third Party Advisory]
https://curl.se/docs/CVE-2021-22901.html [Exploit, Patch, Vendor Advisory]
https://github.com/curl/curl/commit/7f4a9a9b2a49547eae24d2e19bc5c346e9026479 [Patch, Third Party Advisory]
https://hackerone.com/reports/1180380 [Exploit, Issue Tracking, Third Party Advisory]
https://security.netapp.com/advisory/ntap-20210723-0001/ [Third Party Advisory]
https://security.netapp.com/advisory/ntap-20210727-0007/ [Third Party Advisory]
https://www.oracle.com//security-alerts/cpujul2021.html [Patch, Third Party Advisory]
https://www.oracle.com/security-alerts/cpuapr2022.html [Patch, Third Party Advisory]
https://www.oracle.com/security-alerts/cpujan2022.html [Patch, Third Party Advisory]

Authoritative record: CVE-2021-22901 at cve.org

Weaknesses: CWE-416

About this page

This is a reference page, not a dated page of record. It assembles the complete lifecycle of CVE-2021-22901 from the CVE Program record, NVD enrichment, the CISA KEV catalog, EPSS, and OSV advisories. The box score's numbers (CVSS, EPSS, KEV status) are current as of Monday, October 19, 2026 UTC and are re-derived as the archive grows; only dated daily editions are immutable pages of record. The authoritative source for this identifier is cve.org.