CVE-2021-21401
HIGHEPSS 77th pctlDescription
Nanopb is a small code-size Protocol Buffers implementation in ansi C. In Nanopb before versions 0.3.9.8 and 0.4.5, decoding a specifically formed message can cause invalid `free()` or `realloc()` calls if the message type contains an `oneof` field, and the `oneof` directly contains both a pointer field and a non-pointer field. If the message data first contains the non-pointer field and then the pointer field, the data of the non-pointer field is incorrectly treated as if it was a pointer value. Such message data rarely occurs in normal messages, but it is a concern when untrusted data is parsed. This has been fixed in versions 0.3.9.8 and 0.4.5. See referenced GitHub Security Advisory for more information including workarounds.
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:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:L
Exploit Intelligence
Elevated risk: more likely to be exploited than 77% of all known CVEs.
References
Related Vulnerabilities
Other CWE-763 vulnerabilities, ordered by exploit likelihood. View all
| CVE | Severity | CVSS | EPSS | Exploited | Fix |
|---|---|---|---|---|---|
| CVE-2007-4367 | High | 9.3 | 8.2% | - | Fix |
| CVE-2015-2695 | Medium | 5.0 | 6.2% | - | Fix |
| CVE-2013-4695 | High | 7.8 | 5.3% | - | - |
| CVE-2020-36224 | High | 7.5 | 4.3% | - | Fix |
| CVE-2022-31625 | High | 8.1 | 3.4% | - | Fix |
| CVE-2021-42377 | Critical | 9.8 | 3.4% | - | Fix |
Common questions
How do I fix CVE-2021-21401?
Published advisories record a fix for 2 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-2021-21401 being actively exploited?
Not that we know of. CVE-2021-21401 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 1.8% is the estimated probability that it will be exploited in the next 30 days. That is higher than 77% of all scored CVEs.
How severe is CVE-2021-21401?
CVE-2021-21401 has a CVSS v3 base score of 7.1, rated high. 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-2021-21401 affect?
Published advisories record a fix for nanopb (Debian), nanopb (Ubuntu). 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 2024-11-21.