Security readout for executives and security teams
Plain-English summary
CVE-2021-22945 is a memory-safety flaw in libcurl when sending data to an MQTT server. Affected versions can reuse and free already freed memory, creating risk of crash or data exposure in software that uses libcurl’s MQTT functionality.
Executive priority
High priority for environments using MQTT, embedded products, or vendor appliances. The flaw is critical by CVSS and can affect confidentiality and availability, but urgency should be tied to confirmed affected libcurl versions and MQTT usage rather than unsupported exploitation claims.
Technical view
The issue is a CWE-415 double-free/use-after-free condition in libcurl’s MQTT send path for curl 7.73.0 through 7.78.0. The published CVSS 3.1 score is 9.1, network exploitable, low complexity, unauthenticated, no user interaction, with high confidentiality and availability impact.
Likely exposure
Exposure is most likely where applications, embedded systems, or vendor products include affected curl/libcurl versions and use MQTT client functionality to send data. Systems with affected libraries but no MQTT use have lower immediate exposure, but inventories should include bundled dependencies and appliances.
Exploitation context
The source bundle does not show CISA KEV listing or cited active exploitation. Public references include a HackerOne report and multiple vendor advisories, indicating broad downstream impact. Treat exploitability as serious but do not claim in-the-wild exploitation from these sources.
Researcher notes
Key evidence is limited to the CVE description, affected version range, CVSS vector, CWE-415 classification, and downstream advisories. The bundle does not provide exploit status, detailed trigger conditions, or a named fixed version, so remediation should follow authoritative vendor guidance.
Mitigation direction
- Identify all curl/libcurl versions in operating systems, containers, appliances, and application bundles.
- Prioritize removing curl/libcurl 7.73.0 through 7.78.0 from MQTT-capable systems.
- Apply vendor updates or backports from the relevant distribution or product vendor.
- Check Oracle, NetApp, Siemens, Apple, Debian, Gentoo, and Fedora advisories for product-specific guidance.
- If immediate update is unavailable, reduce or disable affected MQTT send functionality where operationally feasible.
Validation and detection
- Confirm whether applications actually use libcurl MQTT send functionality.
- Verify runtime-linked and statically bundled libcurl versions, not only OS package versions.
- Review vendor SBOMs or package manifests for embedded curl/libcurl copies.
- Retest after patching to confirm affected versions are no longer present.
- Document compensating controls for systems awaiting vendor fixes.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-415: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCVE-2021-22945 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- Critical
- CVSS
- 9.1 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H3.95.2Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
9.1CriticalVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H
Source materials
- CVE List V5 sourceCVE List V5
- https://hackerone.com/reports/1269242CVE reference
- FEDORA-2021-fc96a3a749CVE reference · vendor-advisory
- https://www.oracle.com/security-alerts/cpuoct2021.htmlCVE reference
- https://security.netapp.com/advisory/ntap-20211029-0003/CVE reference
- FEDORA-2021-1d24845e93CVE reference · vendor-advisory
- https://cert-portal.siemens.com/productcert/pdf/ssa-389290.pdfCVE reference
- https://support.apple.com/kb/HT213183CVE reference
- DSA-5197CVE reference · vendor-advisory
- GLSA-202212-01CVE reference · vendor-advisory
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Double Free
Double Free represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.