Https://github.com/curl/curl: Business Logic Errors (CVE-2021-22897)
Published Last modified Sources: BSI, OSV, CVE.org
What is affected, what to do
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.
Update essbase to version 11.1.2.4.047, sinec_infrastructure_network_services to version 1.0.1.1, universal_forwarder to version 8.2.12.
- Affected
- Https://github.com/curl/curl
eq 7.61.0 through 7.76.1..7.61.0 through 7.76.1
- Https://github.com/curl/curl
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Metrics
5.3
Priority
XIEM Effective CVSS: highest available CVSS rating from NVD and vendor data.
Source: NVD, CVSS v3
5.3
CVSS v3
Severity Medium on the scale from 0 to 10.
Source: BSI, OSV, CVE.org
4.3 %
EPSS score
Moderate — model estimates 1-10% exploitation likelihood.
Source: FIRST EPSS, percentile 91.1
Show all metrics
- Severity
- Medium
Priority (0–325)
The priority score is a consolidated metric that condenses several individual signals into a single, action-guiding ranking: technical severity (CVSS), exploitation likelihood (EPSS), known-exploited status (KEV) and the context of the affected asset. The aim is to answer the only truly important question in vulnerability management: what first?
Read in glossary- 92.82 Methodology
Exploit maturity
An exploit is code or a technique that specifically uses a concrete vulnerability to force unintended behaviour — such as executing code or escalating privileges. It is the tool that turns a theoretical flaw into a practical attack.
Read in glossary- no public PoC known
XIEM Effective CVSS
XIEM® is the tiered managed-security operating model from NEOSEC and a registered trademark of NEOSEC GmbH. It extends classic SIEM — the central collection, normalisation and correlation of security-relevant events — with endpoint forensics, network visibility and deception technology, and consolidates them into three building tiers: Sentry, Orchestrate and Command.
Read in glossary- 5.3 Methodology
CVSS v3
CVSS is the globally established, open standard for assessing the technical severity of a vulnerability on a scale from 0 to 10. It describes how easily a flaw can be exploited and what damage it can cause — but not how likely its actual exploitation is. CVSS and the complementary EPSS deliberately answer different questions.
Read in glossary- 5.3
EPSS score
The EPSS score is the absolute model output for an individual vulnerability: the estimated probability of real-world exploitation within the next 30 days, expressed as a value between 0 and 1 (i.e. 0 % to 100 %). A score of 0.42 means „the model estimates a 42 % chance of real-world exploitation within 30 days“.
Read in glossary- 4.3 %
- Moderate — model estimates 1-10% exploitation likelihood.
EPSS percentile
The EPSS percentile is the relative position of a vulnerability within all EPSS-scored CVEs, expressed as a value between 0 and 1. A percentile of 0.90 means „this CVE has a higher EPSS score than 90 % of all other scored CVEs“. Unlike the EPSS score, it is not a probability — but a positioning within a ranking.
Read in glossary- 91.1
- Critical — this CVE ranks in the top fifth of all CVEs scored today (rank ≥ 80%).
KEV status
The KEV catalogue is a list maintained by the US authority CISA of vulnerabilities for which active exploitation in the wild has been confirmed. It answers not the question „how severe?“ but „is it already being attacked?“ — thereby sharply prioritising patching.
Read in glossary- —
- Published
- CISA assessment (SSVC)
- Exploitation: proof of concept · automatable · Technical impact: partial
- Source: CISA Vulnrichment, as of 28 May 2026
CWE
CWE is a catalogue of typical weakness types in software and hardware — such as flawed input validation, unsafe memory handling or poor authentication. Where a CVE names a concrete vulnerability in a concrete product, a CWE describes the underlying class of defect.
Read in glossary- CWE-840
Detection rules
No NEOSEC detection rule is available for this vulnerability yet.
Classification under NIS2 and CRA
Rule-based classification from exploitation status and severity. It does not replace a case-by-case assessment.
NIS2
NIS2 is EU Directive (EU) 2022/2555 to raise the level of cybersecurity across the Union. It substantially broadens obligations compared with the first NIS directive: more sectors, mandatory risk management, staged reporting duties and personal accountability of senior management.
Read in glossary- Handle the vulnerability in regular vulnerability handling under Art. 21(2)(e) NIS2.
CRA
The CRA is EU Regulation (EU) 2024/2847 setting horizontal cybersecurity requirements for „products with digital elements“ — from industrial controllers and software to connected consumer devices. For the first time manufacturers must ensure security across the entire product lifecycle, handle vulnerabilities and provide security updates.
Read in glossary- From 11.12.2027, Annex I Part II CRA requires manufacturers of affected products with digital elements to handle vulnerabilities without delay and provide security updates.
ISO/IEC 27001
ISO/IEC 27001 is the internationally leading standard for an information security management system (ISMS). It describes a risk-based, process-oriented framework to systematically plan, implement, review and improve information security.
Read in glossary- Control A.8.8, management of technical vulnerabilities: assess relevance to your systems, plan remediation and keep evidence.
Description
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.
Source: BSI CSAF, BSI WID Portal, OSV (Open Source Vulnerabilities), cvelistv5, NVD (NIST)
Affected products
The following versions are affected. Older releases of the same product line are also vulnerable unless stated otherwise.
| Affected versions | Fixed in | ||
|---|---|---|---|
| — | https://github.com/curl/curl |
|
|
| haxx | curl |
|
|
| netapp | cloud_backup |
|
|
| netapp | solidfire\,_enterprise_sds_\&_hci_storage_node |
|
|
| netapp | solidfire_\&_hci_management_node |
|
|
| 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 |
|
|
| siemens | sinec_infrastructure_network_services |
|
|
| splunk | universal_forwarder |
|
|
Vendors and products
- Google Haxx Curl
- NetApp Intel(R) Processors
- NetApp H300e Firmware
- NetApp H300s Firmware
- NetApp H410s Firmware
- NetApp H500e Firmware
- NetApp H500s Firmware
- NetApp H700e Firmware
- NetApp H700s Firmware
- NetApp Hci Compute Node Firmware
- NetApp Solidfire Baseboard Management Controller Firmware
- NetApp Solidfire\, Enterprise Sds \& Hci Storage Node
Affected operating systems
| Other | netapp | h300e_firmware | — |
| Other | netapp | h300s_firmware | — |
| Other | netapp | h410s_firmware | — |
| Other | netapp | h500e_firmware | — |
| Other | netapp | h500s_firmware | — |
| Other | netapp | h700e_firmware | — |
| Other | netapp | h700s_firmware | — |
| Other | netapp | hci_compute_node_firmware | — |
| Other | netapp | solidfire_baseboard_management_controller_firmware | — |
Weakness classes (CWE)
CWE-840Business Logic Errors
Category
Entry at MITRE CWE-840
References & sources
- hackerone.comreports/1172857x_refsource_MISC
- curl.sedocs/CVE-2021-22897.htmlx_refsource_MISC
- github.comcurl/curl/commit/bbb71507b7bab52002f9b1e0880bed6a32834511x_refsource_MISC
- oracle.comsecurity-alerts/cpujul2021.htmlx_refsource_MISC
- oracle.comsecurity-alerts/cpujan2022.htmlx_refsource_MISC
- security.netapp.comadvisory/ntap-20210727-0007x_refsource_CONFIRM
- oracle.comsecurity-alerts/cpuapr2022.htmlx_refsource_MISC
- Siemens ProductCERTproductcert/pdf/ssa-389290.pdfx_refsource_CONFIRM
- Siemens ProductCERTproductcert/html/ssa-389290.html
- Siemens ProductCERTproductcert/html/ssa-398330.html
Changes to this CVE
Who changed this CVE and when: NVD (analysis, affected products, CVSS), the CVE publisher (CNA) and additional providers such as CISA (ADP).
Record modifiedHackerOne
Show 24 original changes
Individual changes of this event as published by NVD Type Action Before After Reference added —https://cert-portal.siemens.com/productcert/pdf/ssa-389290.pdfReference added —https://curl.se/docs/CVE-2021-22897.htmlReference added —https://github.com/curl/curl/commit/bbb71507b7bab52002f9b1e0880bed6a32834511Reference added —https://hackerone.com/reports/1172857Reference added —https://security.netapp.com/advisory/ntap-20210727-0007/Reference added —https://www.oracle.com//security-alerts/cpujul2021.htmlReference added —https://www.oracle.com/security-alerts/cpuapr2022.htmlReference added —https://www.oracle.com/security-alerts/cpujan2022.htmlReference removed https://cert-portal.siemens.com/productcert/pdf/ssa-389290.pdf—Reference removed https://curl.se/docs/CVE-2021-22897.html—Reference removed https://github.com/curl/curl/commit/bbb71507b7bab52002f9b1e0880bed6a32834511—Reference removed https://hackerone.com/reports/1172857—Reference removed https://security.netapp.com/advisory/ntap-20210727-0007/—Reference removed https://www.oracle.com//security-alerts/cpujul2021.html—Reference removed https://www.oracle.com/security-alerts/cpuapr2022.html—Reference removed https://www.oracle.com/security-alerts/cpujan2022.html—Reference type removed https://cert-portal.siemens.com/productcert/pdf/ssa-389290.pdf Types: Patch, Third Party Advisory—Reference type removed https://curl.se/docs/CVE-2021-22897.html Types: Patch, Vendor Advisory—Reference type removed https://github.com/curl/curl/commit/bbb71507b7bab52002f9b1e0880bed6a32834511 Types: Patch, Third Party Advisory—Reference type removed https://hackerone.com/reports/1172857 Types: Exploit, Issue Tracking, Third Party Advisory—Reference type removed https://security.netapp.com/advisory/ntap-20210727-0007/ Types: Third Party Advisory—Reference type removed https://www.oracle.com//security-alerts/cpujul2021.html Types: Patch, Third Party Advisory—Reference type removed https://www.oracle.com/security-alerts/cpuapr2022.html Types: Patch, Third Party Advisory—Reference type removed https://www.oracle.com/security-alerts/cpujan2022.html Types: Patch, Third Party Advisory—Source identifier: support@hackerone.com
Record modifiedCISA ADP
New references:Show 3 original changes
Individual changes of this event as published by NVD Type Action Before After Reference added —https://hackerone.com/reports/1172857Reference removed https://hackerone.com/reports/1172857—Reference type removed https://hackerone.com/reports/1172857 Types: Exploit, Issue Tracking, Third Party Advisory—Source identifier: 134c704f-9b21-4f2e-91b3-4a467353bcc0
Record modifiedCVE Program
Show 24 original changes
Individual changes of this event as published by NVD Type Action Before After Reference added —https://cert-portal.siemens.com/productcert/pdf/ssa-389290.pdfReference added —https://curl.se/docs/CVE-2021-22897.htmlReference added —https://github.com/curl/curl/commit/bbb71507b7bab52002f9b1e0880bed6a32834511Reference added —https://hackerone.com/reports/1172857Reference added —https://security.netapp.com/advisory/ntap-20210727-0007/Reference added —https://www.oracle.com//security-alerts/cpujul2021.htmlReference added —https://www.oracle.com/security-alerts/cpuapr2022.htmlReference added —https://www.oracle.com/security-alerts/cpujan2022.htmlReference removed https://cert-portal.siemens.com/productcert/pdf/ssa-389290.pdf—Reference removed https://curl.se/docs/CVE-2021-22897.html—Reference removed https://github.com/curl/curl/commit/bbb71507b7bab52002f9b1e0880bed6a32834511—Reference removed https://hackerone.com/reports/1172857—Reference removed https://security.netapp.com/advisory/ntap-20210727-0007/—Reference removed https://www.oracle.com//security-alerts/cpujul2021.html—Reference removed https://www.oracle.com/security-alerts/cpuapr2022.html—Reference removed https://www.oracle.com/security-alerts/cpujan2022.html—Reference type removed https://cert-portal.siemens.com/productcert/pdf/ssa-389290.pdf Types: Patch, Third Party Advisory—Reference type removed https://curl.se/docs/CVE-2021-22897.html Types: Patch, Vendor Advisory—Reference type removed https://github.com/curl/curl/commit/bbb71507b7bab52002f9b1e0880bed6a32834511 Types: Patch, Third Party Advisory—Reference type removed https://hackerone.com/reports/1172857 Types: Exploit, Issue Tracking, Third Party Advisory—Reference type removed https://security.netapp.com/advisory/ntap-20210727-0007/ Types: Third Party Advisory—Reference type removed https://www.oracle.com//security-alerts/cpujul2021.html Types: Patch, Third Party Advisory—Reference type removed https://www.oracle.com/security-alerts/cpuapr2022.html Types: Patch, Third Party Advisory—Reference type removed https://www.oracle.com/security-alerts/cpujan2022.html Types: Patch, Third Party Advisory—Source identifier: af854a3a-2127-422b-91ae-364da2661108
Record modifiedSiemens ADP
Show 3 original changes
Individual changes of this event as published by NVD Type Action Before After Affected versions (publisher) added —New affected value received. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2021/22xxx/CVE-2021-22897.json">CVE-2021-22897</a>Reference added —https://cert-portal.siemens.com/productcert/html/ssa-389290.htmlReference added —https://cert-portal.siemens.com/productcert/html/ssa-398330.htmlSource identifier: 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e
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