CVE-2021-47294
MEDIUMDescription
In the Linux kernel, the following vulnerability has been resolved: netrom: Decrease sock refcount when sock timers expire Commit 63346650c1a9 ("netrom: switch to sock timer API") switched to use sock timer API. It replaces mod_timer() by sk_reset_timer(), and del_timer() by sk_stop_timer(). Function sk_reset_timer() will increase the refcount of sock if it is called on an inactive timer, hence, in case the timer expires, we need to decrease the refcount ourselves in the handler, otherwise, the sock refcount will be unbalanced and the sock will never be freed.
How to fix
TridentStack Control can deploy fixes like this automatically across your Windows, macOS, and Linux fleet. See how it works
Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.
CVSS v3 Vector
Exploitability
Impact
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Exploit Intelligence
Low risk: more likely to be exploited than 20% of all known CVEs.
References
Related Vulnerabilities
Other CWE-672 vulnerabilities, ordered by exploit likelihood. View all
| CVE | Severity | CVSS | EPSS | Exploited | Fix |
|---|---|---|---|---|---|
| CVE-2024-23638 | Medium | 6.5 | 60% | - | Fix |
| CVE-2020-11027 | Medium | 6.1 | 14% | - | Fix |
| CVE-2019-17638 | Critical | 9.4 | 11% | - | Fix |
| CVE-2009-3547 | High | 7.0 | 4.9% | - | - |
| CVE-2019-15691 | High | 7.2 | 4.7% | - | Fix |
| CVE-2020-24030 | Critical | 9.8 | 2.7% | - | - |
Common questions
How do I fix CVE-2021-47294?
Published advisories record a fix for 21 affected products. The "How to fix" section on this page lists the fixed version and source advisory for each one, so apply the entry matching what you actually run.
Is CVE-2021-47294 being actively exploited?
Not that we know of. CVE-2021-47294 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 0.28% is the estimated probability that it will be exploited in the next 30 days. That is higher than 20% of all scored CVEs.
How severe is CVE-2021-47294?
CVE-2021-47294 has a CVSS v3 base score of 5.5, rated medium. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.
What does CVE-2021-47294 affect?
Published advisories record a fix for linux (Debian), linux (Ubuntu), linux-aws (Ubuntu), linux-fips (Ubuntu), and 17 more. Only products with a sourced advisory are listed, so treat this as what we can cite rather than a complete inventory.
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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2025-06-23.