# CVE-2020-37239: libbabl 0.1.62 Broken Double Free Detection Memory Safety

> Attackers can bypass double-free detection in libbabl to achieve memory corruption and potential code execution.

- **Severity:** Critical 9.3 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 16 May 2026
- **Updated:** 18 May 2026
- **Also known as:** GHSA-4fvf-cvgm-9hvc, UBUNTU-CVE-2020-37239

## What is CVE-2020-37239?

CVE-2020-37239 is a critical memory corruption vulnerability in Gegl libbabl, published on 16 May 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

libbabl 0.1.62 contains a broken double free detection vulnerability that allows attackers to bypass memory safety checks by exploiting signature overwriting in freed chunks. Attackers can call babl_free() twice on the same pointer without triggering detection, as libc's malloc metadata overwrites babl's signature field upon freeing, enabling potential memory corruption and code execution.

Weakness: CWE-415 (Double Free)

## Which versions are affected by CVE-2020-37239?


## How do I fix CVE-2020-37239?

No fix has been published for CVE-2020-37239 yet. Limit exposure of the affected software until one is available.

## Is CVE-2020-37239 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2020-37239 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2020-37239 and fix it if it is affected.

What it is: CVE-2020-37239 is a critical memory corruption vulnerability in Gegl libbabl, published on 16 May 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2020-37239 exists.

Affected product: Gegl libbabl. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2020-37239/ (Markdown: https://insights.sbomify.com/CVE-2020-37239/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-37239
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-37239
- OSV: https://osv.dev/vulnerability/CVE-2020-37239

---
From sbomify Insights: https://insights.sbomify.com/CVE-2020-37239/
Summaries are generated and may contain mistakes; the official description above is the record.