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CVE-2021-21401— Invalid free() call in Nanopb

Quick assessment

Affected
nanopb nanopb
Exploitation
Public or AI PoC available; prioritize validation
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Nanopb是Nanopb个人开发者的一个适用于微处理器的协议缓冲区实现。 Nanopb 存在安全漏洞，该漏洞导致无效的“free()”或“realloc()的调用。

CVSS 7.1 · High EPSS 1.81% · P78

Possible ATT&CK Techniques 1 AI

T1190 · Exploit Public-Facing Application
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I. Basic Information for CVE-2021-21401

Vulnerability Information
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Vulnerability Title
Invalid free() call in Nanopb
Source: CVE Program / CVE List V5
Vulnerability 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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:L
Source: CVE Program / CVE List V5
Vulnerability Type
对无效指针或索引的释放
Source: CVE Program / CVE List V5
Vulnerability Title
Nanopb 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Nanopb是Nanopb个人开发者的一个适用于微处理器的协议缓冲区实现。 Nanopb 存在安全漏洞，该漏洞导致无效的“free()”或“realloc()的调用。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
nanopb nanopb >= 0.3.2, <= 0.3.9.7 -

II. Public POCs for CVE-2021-21401

# POC Description Source Link Shenlong Link
1 None https://github.com/uthrasri/CVE-2021-21401_nanopb-c_AOSP10_R33 POC Details
2 None https://github.com/HimanshuS67/external_nanopb-c_AOSP10_CVE-2021-21401 POC Details
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III. Intelligence Information for CVE-2021-21401

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Patches & Fixes for CVE-2021-21401 (1)

Vendor Advisories for CVE-2021-21401 (1)

Other References for CVE-2021-21401 (2)

IV. Related Vulnerabilities

Same product: nanopb
Same vendor: nanopb
Same weakness: CWE-763