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    CVE-2021-22897

    curl 7.61.0 through 7.76.1 suffers from exposure of data element to wrong session due to a mistake in the code for CURLOPT_SSL_CIPHER_LIST when libcurl is built to use the Schannel TLS library. The selected cipher set was stored in a single "static" variable in the library, which has the surprising side-effect that if an application sets up multiple concurrent transfers, the last one that sets the ciphers will accidentally control the set used by all transfers. In a worst-case scenario, this weakens transport security significantly.

    Published:May 26, 2021
    Last Modified:May 28, 2026
    EPS:Jun 11, 2021
    EPSS Score:0.00791
    CVSS Score:5.3

    Affected Products

    Vendor
    Haxx
    Product
    Curl
    Vendor
    Netapp
    Product
    Cloud Backup
    Vendor
    Netapp
    Product
    H300e
    Vendor
    Netapp
    Product
    H300e Firmware
    Vendor
    Netapp
    Product
    H300s
    Vendor
    Netapp
    Product
    H300s Firmware
    Vendor
    Netapp
    Product
    H410s
    Vendor
    Netapp
    Product
    H410s Firmware
    Vendor
    Netapp
    Product
    H500e
    Vendor
    Netapp
    Product
    H500e Firmware
    Vendor
    Netapp
    Product
    H500s
    Vendor
    Netapp
    Product
    H500s Firmware
    Vendor
    Netapp
    Product
    H700e
    Vendor
    Netapp
    Product
    H700e Firmware
    Vendor
    Netapp
    Product
    H700s
    Vendor
    Netapp
    Product
    H700s Firmware
    Vendor
    Netapp
    Product
    Hci Compute Node
    Vendor
    Netapp
    Product
    Hci Compute Node Firmware
    Vendor
    Netapp
    Product
    Solidfire\, Enterprise Sds \& Hci Storage Node
    Vendor
    Netapp
    Product
    Solidfire \& Hci Management Node
    Vendor
    Netapp
    Product
    Solidfire Baseboard Management Controller Firmware
    Vendor
    Oracle
    Product
    Communications Cloud Native Core Binding Support Function
    Vendor
    Oracle
    Product
    Communications Cloud Native Core Network Function Cloud Native Environment
    Vendor
    Oracle
    Product
    Communications Cloud Native Core Network Repository Function
    Vendor
    Oracle
    Product
    Communications Cloud Native Core Network Slice Selection Function
    Vendor
    Oracle
    Product
    Communications Cloud Native Core Service Communication Proxy
    Vendor
    Oracle
    Product
    Essbase
    Vendor
    Oracle
    Product
    Mysql Server
    Vendor
    Siemens
    Product
    Sinec Infrastructure Network Services
    Vendor
    Splunk
    Product
    Universal Forwarder

    Exploits

    https://hackerone.com/reports/1172857https://hackerone.com/reports/1172857https://hackerone.com/reports/1172857

    Related CVEs

    CVE-2026-7168 (CVSS 5.3) — Successfully using libcurl to do a transfer over a specific HTTP proxy (`proxyA`) with **Digest** authenticati…
    CVE-2026-7009 (CVSS 5.3) — When curl is told to use the Certificate Status Request TLS extension, often referred to as *OCSP stapling*, t…
    CVE-2026-6429 (CVSS 5.3) — When asked to both use a `.netrc` file for credentials and to follow HTTP redirects, libcurl could leak the pa…
    CVE-2026-4873 (CVSS 5.9) — A vulnerability exists where a connection requiring TLS incorrectly reuses an existing unencrypted connection …
    CVE-2026-6253 (CVSS 5.9) — curl might erroneously pass on credentials for a first proxy to a second proxy. This can happen when the foll…
    CVE-2026-5773 (CVSS 7.5) — libcurl might in some circumstances reuse the wrong connection for SMB(S) transfers. libcurl features a pool …
    CVE-2026-5545 (CVSS 6.5) — libcurl might in some circumstances reuse the wrong connection when asked to do an authenticated HTTP(S) reque…
    CVE-2026-6276 (CVSS 7.5) — Using libcurl, when a custom `Host:` header is first set for an HTTP request and a second request is subsequen…
    CVE-2026-3805 (CVSS 7.5) — When doing a second SMB request to the same host again, curl would wrongly use a data pointer pointing into al…
    CVE-2026-3784 (CVSS 6.5) — curl would wrongly reuse an existing HTTP proxy connection doing CONNECT to a server, even if the new request …

    References

    https://cert-portal.siemens.com/productcert/pdf/ssa-389290.pdf
    https://curl.se/docs/CVE-2021-22897.html
    https://github.com/curl/curl/commit/bbb71507b7bab52002f9b1e0880bed6a32834511
    https://hackerone.com/reports/1172857
    https://security.netapp.com/advisory/ntap-20210727-0007/
    https://www.oracle.com//security-alerts/cpujul2021.html
    https://www.oracle.com/security-alerts/cpuapr2022.html
    https://www.oracle.com/security-alerts/cpujan2022.html
    https://cert-portal.siemens.com/productcert/pdf/ssa-389290.pdf
    https://curl.se/docs/CVE-2021-22897.html
    https://github.com/curl/curl/commit/bbb71507b7bab52002f9b1e0880bed6a32834511
    https://hackerone.com/reports/1172857
    https://security.netapp.com/advisory/ntap-20210727-0007/
    https://www.oracle.com//security-alerts/cpujul2021.html
    https://www.oracle.com/security-alerts/cpuapr2022.html
    https://www.oracle.com/security-alerts/cpujan2022.html
    https://hackerone.com/reports/1172857

    Common Vulnerability Scoring System

    Attack Vector
    Network
    Adjacent
    Local
    Physical
    Privileges Required
    None
    Low
    High
    User Interaction
    None
    Required
    Scope
    Unchanged
    Changed
    Confidentiality
    None
    Low
    High
    Integrity
    None
    Low
    High
    Availability
    None
    Low
    High