CVE-2021-22924 — libcurl keeps previously used connections in a connection pool for subsequenttransfers to reuse,...
libcurl keeps previously used connections in a connection pool for subsequenttransfers to reuse, if one of them matches the setup.Due to errors in the logic, the config matching function did not take 'issuercert' into account and it compared the involved paths *case insensitively*,which could lead to libcurl reusing wrong connections.File paths are, or can be, case sensitive on many systems but not all, and caneven vary depending on used file systems.The comparison also didn't include the 'issuer cert' which a transfer can setto qualify how to verify the server certificate.
Who exploits it and how urgent it is
A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.
How the score was calculated
- EPSS 6.3% (30-day exploitation probability)+14
- CISA SSVC: exploitation "poc"+5
The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).
Triage
Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.
CISA SSVC assessment CISA
Three decision points CISA publishes for the CVEs it assesses (SSVC 2.0.3). A stakeholder decision, not a severity score.
Remediation
Fixes and mitigations documented by the sources — linked to the original advisory.
- Documented patch — cert-portal.siemens.com (NIST National Vulnerability Database)
- Documented patch — hackerone.com (NIST National Vulnerability Database)
- Documented patch — www.oracle.com (NIST National Vulnerability Database)
- Documented patch — www.oracle.com (NIST National Vulnerability Database)
First 24 hours
Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.
- Identify exposed assets running the affected vendor/product/version combinations (Debian Debian Linux, Fedoraproject Fedora, Haxx Libcurl…).
- The attack is network-based and needs no privileges: restrict exposure (ACLs, VPN, WAF) until patched.
- Apply the fixed version or the patch documented under Remediation.
- EPSS ahead of 93% of scored CVEs: prioritize it in the patch queue.
- Search available logs for exploit probes matching the vulnerability class (file handling), errors and authentication anomalies.
Affected scope
Vendor, product and versions as the sources word them.
| Vendor | Product | Versions | Status | Source |
|---|---|---|---|---|
| Debian | Debian Linux | version 9.0version 10.0version 11.0 | Vulnerable | NIST National Vulnerability Database |
| Fedoraproject | Fedora | version 33 | Vulnerable | NIST National Vulnerability Database |
| Haxx | Libcurl | ≥ 7.10.4 and < 7.77.0 | Vulnerable | NIST National Vulnerability Database |
| Netapp | Cloud Backup | versions not specified by the source | Vulnerable | NIST National Vulnerability Database |
| Netapp | Clustered Data Ontap | versions not specified by the source | Vulnerable | NIST National Vulnerability Database |
| Netapp | Solidfire & Hci Management Node | versions not specified by the source | Vulnerable | NIST National Vulnerability Database |
| Netapp | Solidfire Baseboard Management Controller Firmware | versions not specified by the source | Vulnerable | NIST National Vulnerability Database |
| Oracle | Mysql Server | ≥ 5.7.0 and ≤ 5.7.36≥ 8.0.0 and ≤ 8.0.26 | Vulnerable | NIST National Vulnerability Database |
| Oracle | Peoplesoft Enterprise Peopletools | version 8.57version 8.59version 8.58 | Vulnerable | NIST National Vulnerability Database |
| Siemens | Logo! Cmr2020 Firmware | versions not specified by the source | Vulnerable | NIST National Vulnerability Database |
| Siemens | Logo! Cmr2040 Firmware | versions not specified by the source | Vulnerable | NIST National Vulnerability Database |
| Siemens | Ruggedcomrm 1224 Lte Firmware | < 7.1 | Vulnerable | NIST National Vulnerability Database |
| Siemens | Scalance M804pb Firmware | < 7.1 | Vulnerable | NIST National Vulnerability Database |
| Siemens | Scalance M812-1 Firmware | < 7.1 | Vulnerable | NIST National Vulnerability Database |
| Siemens | Scalance M816-1 Firmware | < 7.1 | Vulnerable | NIST National Vulnerability Database |
| Siemens | Scalance M826-2 Firmware | < 7.1 | Vulnerable | NIST National Vulnerability Database |
| Siemens | Scalance M874-2 Firmware | < 7.1 | Vulnerable | NIST National Vulnerability Database |
| Siemens | Scalance M874-3 Firmware | < 7.1 | Vulnerable | NIST National Vulnerability Database |
| Siemens | Scalance M876-3 Firmware | < 7.1 | Vulnerable | NIST National Vulnerability Database |
| Siemens | Scalance M876-4 Firmware | < 7.1 | Vulnerable | NIST National Vulnerability Database |
| Siemens | Scalance Mum856-1 Firmware | < 7.1 | Vulnerable | NIST National Vulnerability Database |
| Siemens | Scalance S615 Firmware | < 7.1 | Vulnerable | NIST National Vulnerability Database |
| Siemens | Simatic Cp 1543-1 Firmware | < 3.0.22 | Vulnerable | NIST National Vulnerability Database |
| Siemens | Simatic Cp 1545-1 Firmware | < 1.1 | Vulnerable | NIST National Vulnerability Database |
| Siemens | Simatic Rtu 3041c Firmware | < 5.0.14 | Vulnerable | NIST National Vulnerability Database |
| Siemens | Simatic Rtu3010c Firmware | < 5.0.14 | Vulnerable | NIST National Vulnerability Database |
| Siemens | Simatic Rtu3030c Firmware | < 5.0.14 | Vulnerable | NIST National Vulnerability Database |
| Siemens | Simatic Rtu3031c Firmware | < 5.0.14 | Vulnerable | NIST National Vulnerability Database |
| Siemens | Sinec Infrastructure Network Services | < 1.0.1.1 | Vulnerable | NIST National Vulnerability Database |
| Siemens | Sinema Remote Connect | < 3.1 | Vulnerable | NIST National Vulnerability Database |
| Siemens | Sinema Remote Connect Server | < 3.1 | Vulnerable | NIST National Vulnerability Database |
| Siemens | Siplus Net Cp 1543-1 Firmware | < 3.0.22 | Vulnerable | NIST National Vulnerability Database |
| Splunk | Universal Forwarder | version 9.1.0≥ 9.0.0 and < 9.0.6≥ 8.2.0 and < 8.2.12 | Vulnerable | NIST National Vulnerability Database |
Attack characteristics
The CVSS vector, decoded. It describes the attack, not your exposure to it.
Every base score collected
Sources score independently and may disagree; each row says who scored it and under which version.
| Score | Version | Severity | Expl. | Impact | Scored by |
|---|---|---|---|---|---|
| 3.7 | CVSS 3.1 | Low | 2.2 | 1.4 | nvd@nist.gov via NIST National Vulnerability Database |
| 3.7 | CVSS 3.1 | Low | 2.2 | 1.4 | 134c704f-9b21-4f2e-91b3-4a467353bcc0 via NIST National Vulnerability Database |
| 3.7 | CVSS 3.1 | Low | — | — | GitHub, Inc. via GitHub Security Advisories |
| 3.7 | CVSS 3.1 | Low | — | — | CISA-ADP via CVE Program (cve.org) e CISA ADP |
| 4.3 | CVSS 2.0 | Medium | 8.6 | 2.9 | nvd@nist.gov via NIST National Vulnerability Database |
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N (score shown at the top: nvd@nist.gov) Weakness MITRE
Weakness class according to MITRE’s CWE catalog.
EPSS over time FIRST
Oct 13, 2026 → Oct 14, 2026 · 2 reading(s) · max 6.27%
Detection
Read off the CVSS vector and the weakness class. Starting points, not tested rules.
- Prioritize edge telemetry for the network-reachable component (proxy, WAF, IDS/IPS).
- Monitor file creation in web directories and paths with traversal sequences (../).
Timeline
What happened to this CVE, newest first.
- 2026
- SSVC assessment updated
- Record published
- Fix documented
- Affected products added · haxx/libcurl, fedoraproject/fedora, debian/debian linux, netapp/cloud backup, netapp/clustered data ontap, netapp/solidf
- CVSS changed · 3.7
- Source status changed · → Modified
- Record created in this database
- 2021
- CVE published
Source activity
Repeated readings are counted rather than listed.
- 2× References added · Oct 14, 2026 – Oct 14, 2026
- 1× Official description updated · Oct 14, 2026 – Oct 14, 2026
References
28 on the record
- www.oracle.com/security-alerts/cpuoct2021.html
- hackerone.com/reports/1223565
- cert-portal.siemens.com/productcert/pdf/ssa-389290.pdf
- www.oracle.com/security-alerts/cpujan2022.html
- cert-portal.siemens.com/productcert/pdf/ssa-484086.pdf
- security.netapp.com/advisory/ntap-20210902-0003/
- cert-portal.siemens.com/productcert/html/ssa-732250.html
- lists.apache.org/thread.html/rbf4ce74b0d1fa9810dec50ba3ace0caeea677af7c27a97111c06ccb7
- lists.apache.org/thread.html/r61db8e7dcb56dc000a5387a88f7a473bacec5ee01b9ff3f55308aacc
- www.debian.org/security/2022/dsa-5197
- lists.debian.org/debian-lts-announce/2022/08/msg00017.html
- lists.apache.org/thread.html/rbf4ce74b0d1fa9810dec50ba3ace0caeea677af7c27a97111c06ccb7
- security.netapp.com/advisory/ntap-20210902-0003
- cert-portal.siemens.com/productcert/pdf/ssa-732250.pdf
- lists.apache.org/thread.html/rbf4ce74b0d1fa9810dec50ba3ace0caeea677af7c27a97111c06ccb7
- nvd.nist.gov/vuln/detail/CVE-2021-22924
- github.com/advisories/GHSA-qhhj-q26m-mrw8
- cert-portal.siemens.com/productcert/html/ssa-398330.html
- lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/FRUC
- cert-portal.siemens.com/productcert/html/ssa-389290.html
- lists.apache.org/thread.html/r61db8e7dcb56dc000a5387a88f7a473bacec5ee01b9ff3f55308aacc
- lists.apache.org/thread.html/r61db8e7dcb56dc000a5387a88f7a473bacec5ee01b9ff3f55308aacc
- lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/FRUCW2
- lists.apache.org/thread.html/rbf4ce74b0d1fa9810dec50ba3ace0caeea677af7c27a97111c06ccb7
- lists.apache.org/thread.html/r61db8e7dcb56dc000a5387a88f7a473bacec5ee01b9ff3f55308aacc
- cert-portal.siemens.com/productcert/html/ssa-484086.html
- lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/FRUC
- lists.debian.org/debian-lts-announce/2021/08/msg00017.html
Elsewhere on this site
Related CVEs (same products)
- High CVE-2026-87264 Improper Access Control in Oracle Peoplesoft Enterprise Peopletools Sep 15, 2026
- High CVE-2026-83017 Improper Access Control in Oracle Peoplesoft Enterprise Peopletools Sep 15, 2026
- High CVE-2026-83019 Improper Access Control in Oracle Peoplesoft Enterprise Peopletools Sep 15, 2026
- High CVE-2026-83018 Improper Access Control in Oracle Peoplesoft Enterprise Peopletools Sep 15, 2026
- High CVE-2026-83016 Improper Access Control in Oracle Peoplesoft Enterprise Peopletools Sep 15, 2026
- High CVE-2026-83014 Improper Access Control in Oracle Peoplesoft Enterprise Peopletools Sep 15, 2026
Not in any source we poll
Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.
- No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
- No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
- No exploit packet captures, log samples, or incident case IDs supplied.
Answered from this record
Text assembled only from the fields above — no additional claims.
What should defenders know first?
CVE-2021-22924 is "libcurl keeps previously used connections in a connection pool for subsequenttransfers to reuse,...", rated Low. It affects Debian Linux (Debian); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 3.7 describes technical severity. EPSS 6.27% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.
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