CVE-2021-22901 — curl 7.75.0 through 7.76.1 suffers from a use-after-free vulnerability resulting in already freed...

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 — curl.se (NIST National Vulnerability Database)
• Documented patch — github.com (NIST National Vulnerability Database)
• Documented patch — www.oracle.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.

1. Identify exposed assets running the affected vendor/product/version combinations (Haxx Curl, Netapp Active Iq Unified Manager, Netapp Cloud Backup…).
2. The attack is network-based and needs no privileges: restrict exposure (ACLs, VPN, WAF) until patched.
3. Apply the fixed version or the patch documented under Remediation.
4. EPSS ahead of 99% of scored CVEs: prioritize it in the patch queue.
5. Search available logs for exploit probes matching the vulnerability class (memory corruption), errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

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.

Weakness MITRE

Weakness class according to MITRE’s CWE catalog.

CWE-416 · Use After Free

Other CVEs with this weakness →

EPSS over time FIRST

Oct 13, 2026 → Oct 14, 2026 · 2 reading(s) · max 60.12%

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).
• Correlate service crashes/restarts with inbound traffic; repeated crashes may indicate attempts.

Timeline

What happened to this CVE, newest first.

• 2026
• SSVC assessment updated
  Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
• Record published
  Oct 13, 2026
• Fix documented
  Oct 13, 2026 · NIST National Vulnerability Database
• CVSS changed · 8.1
  Oct 13, 2026 · NIST National Vulnerability Database
• Source status changed · → Modified
  Oct 13, 2026 · NIST National Vulnerability Database
• Record created in this database
  Oct 13, 2026 · NIST National Vulnerability Database
• 2021
• CVE published
  Jun 11, 2021 · hackerone

Source activity

Repeated readings are counted rather than listed.

• 2× References added · Oct 13, 2026 – Oct 14, 2026
• 1× Official description updated · Oct 13, 2026 – Oct 13, 2026

References

17 on the record

• www.oracle.com//security-alerts/cpujul2021.html
  Patch, Third Party Advisory, x_refsource_MISC, NIST National Vulnerability Database
• www.oracle.com/security-alerts/cpuapr2022.html
  Patch, Third Party Advisory, x_refsource_MISC, NIST National Vulnerability Database
• www.oracle.com/security-alerts/cpujan2022.html
  Patch, Third Party Advisory, x_refsource_MISC, NIST National Vulnerability Database
• curl.se/docs/CVE-2021-22901.html
  Exploit, Patch, Vendor Advisory, x_refsource_MISC, NIST National Vulnerability Database
• github.com/curl/curl/commit/7f4a9a9b2a49547eae24d2e19bc5c346e9026479
  Patch, Third Party Advisory, x_refsource_MISC, NIST National Vulnerability Database
• cert-portal.siemens.com/productcert/pdf/ssa-389290.pdf
  Patch, Third Party Advisory, x_refsource_CONFIRM, NIST National Vulnerability Database
• security.netapp.com/advisory/ntap-20210723-0001
  GitHub Security Advisories
• cert-portal.siemens.com/productcert/html/ssa-732250.html
  NIST National Vulnerability Database
• hackerone.com/reports/1180380
  Exploit, Issue Tracking, Third Party Advisory, x_refsource_MISC, NIST National Vulnerability Database
• nvd.nist.gov/vuln/detail/CVE-2021-22901
  GitHub Security Advisories
• security.netapp.com/advisory/ntap-20210727-0007
  GitHub Security Advisories
• cert-portal.siemens.com/productcert/pdf/ssa-732250.pdf
  Third Party Advisory, x_refsource_CONFIRM, NIST National Vulnerability Database
• github.com/advisories/GHSA-vjwf-ghhc-2p8q
  GitHub Security Advisories
• cert-portal.siemens.com/productcert/html/ssa-398330.html
  NIST National Vulnerability Database
• security.netapp.com/advisory/ntap-20210723-0001/
  Third Party Advisory, x_refsource_CONFIRM, NIST National Vulnerability Database
• security.netapp.com/advisory/ntap-20210727-0007/
  Third Party Advisory, x_refsource_CONFIRM, NIST National Vulnerability Database
• cert-portal.siemens.com/productcert/html/ssa-389290.html
  NIST National Vulnerability Database

Elsewhere on this site

Related CVEs (same products)

• Critical CVE-2024-54085 AMI MegaRAC SPx Authentication Bypass by Spoofing Vulnerability KEV Mar 11, 2025
• High CVE-2025-0665 eventfd double close Feb 5, 2025
• Low CVE-2025-0167 netrc and default credential leak Feb 5, 2025
• High CVE-2025-0725 gzip integer overflow Feb 5, 2025
• High CVE-2025-0411 7-Zip Mark of the Web Bypass Vulnerability KEV Jan 25, 2025
• Low CVE-2024-11053 netrc and redirect credential leak Dec 11, 2024

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-2021-22901 is "curl 7.75.0 through 7.76.1 suffers from a use-after-free vulnerability resulting in already freed...", rated High. It affects Curl (Haxx); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 8.1 describes technical severity. EPSS 60.12% 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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