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CVE-2021-21401

HIGHCVSS 7.1/10EPSS 1.81%

Last modified

CVE-2021-21401 is a high-severity vulnerability rated 7.1/10 on the CVSS scale. 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. EPSS estimates a 1.81% chance of exploitation in the next 30 days.

Description

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.

Metrics

CVSS 3.1
7.1/10

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:L

EPSS Probability
1.81%

75.9th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

VendorProductVersions
Nanopb ProjectNanopb< 0.3.9.8
Nanopb ProjectNanopb>= 0.4.0, < 0.4.5

References

Timeline

Published
Last Modified
Status
Modified

Frequently Asked Questions

What is CVE-2021-21401?
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 severe is CVE-2021-21401?
CVE-2021-21401 has a CVSS score of 7.1/10 (HIGH severity). The EPSS model estimates a 1.81% probability of exploitation in the next 30 days.
How do I fix CVE-2021-21401?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2021-21401?

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Source: NVD / NIST