CVE-2020-5235Network attack vector

Crash or memory corruption via invalid free

Published Feb 4, 2020 · Updated Aug 4, 2024

Invalid memory release in Nanopb before 0.2.9.4, 0.3.0 through 0.3.9.4, and 0.4.0 allows attackers to crash or corrupt a decoding process. The decode_pointer_field path increments the repeated-field count before allocation succeeds, so failed realloc leaves an uninitialized new slot that cleanup passes to free. Exploitation requires PB_ENABLE_MALLOC, a repeated string, bytes, or message field, and memory exhaustion during array growth; the result is a crash or further memory corruption.

CVSS severity6.5
Medium
EPSS probability1.73%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Invalid memory release in Nanopb before 0.2.9.4, 0.3.0 through 0.3.9.4, and 0.4.0 allows attackers to crash or corrupt a decoding process. The decode_pointer_field path increments the repeated-field count before allocation succeeds, so failed realloc leaves an uninitialized new slot that cleanup passes to free. Exploitation requires PB_ENABLE_MALLOC, a repeated string, bytes, or message field, and memory exhaustion during array growth; the result is a crash or further memory corruption.

The record

CVE
CVE-2020-5235
Published
Feb 4, 2020
Updated
Aug 4, 2024
Vendor
Nanopb
Product
Nanopb
Classifications
CWE-125
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 4, 2020CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 0.2.9.4
  2. Affected versionversion=>= 0.3.0, < 0.3.9.5
  3. Affected versionversion=>= 0.4.0, < 0.4.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Nanopb · Nanopbversion=< 0.2.9.4; version=>= 0.3.0, < 0.3.9.5; version=>= 0.4.0, < 0.4.1

Published CVSS scores

6.5GitHub CNACVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:L/A:L

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-125Out-of-bounds Read

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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