# CVE-2020-18899: Denial of service in n/a

> Attackers can cause a denial of service in applications using Exiv2 by providing crafted input that triggers uncontrolled memory allocation.

- **Severity:** Medium 6.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 19 Aug 2021
- **Updated:** 15 Oct 2024
- **Also known as:** DEBIAN-CVE-2020-18899, GHSA-44mj-pwh6-pw78, PYSEC-2021-879

## What is CVE-2020-18899?

CVE-2020-18899 is a medium-severity denial of service vulnerability in Exiv2 Exiv2, published on 19 Aug 2021. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

### Official description

An uncontrolled memory allocation in DataBufdata(subBox.length-sizeof(box)) function of Exiv2 0.27 allows attackers to cause a denial of service (DOS) via a crafted input.

Weakness: CWE-770 (Allocation of Resources Without Limits or Throttling)

## Which versions are affected by CVE-2020-18899?

1 open source package ship an affected version, including exiv2. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `exiv2` | PyPI | All versions | None |

Products: Exiv2 Exiv2.

## How do I fix CVE-2020-18899?

Upgrade to a fixed version.

## Is CVE-2020-18899 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2020-18899 exists.

## Other vulnerabilities in Exiv2 Exiv2

- [CVE-2023-44398](https://insights.sbomify.com/CVE-2023-44398/): Out-of-bounds write in exiv2 (high 8.8)
- [CVE-2019-9143](https://insights.sbomify.com/CVE-2019-9143/): Denial of service in n/a (high 8.8)
- [CVE-2019-9144](https://insights.sbomify.com/CVE-2019-9144/): Denial of service in n/a (high 8.8)
- [CVE-2018-14046](https://insights.sbomify.com/CVE-2018-14046/): Memory corruption in n/a (high 8.8)
- [CVE-2017-12955](https://insights.sbomify.com/CVE-2017-12955/): Memory corruption in n/a (high 8.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2020-18899 and fix it if it is affected.

What it is: CVE-2020-18899 is a medium-severity denial of service vulnerability in Exiv2 Exiv2, published on 19 Aug 2021. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2020-18899 exists.

Affected packages and fixed versions:
- exiv2 (PyPI): affected all versions; no fix listed

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-2020-18899/ (Markdown: https://insights.sbomify.com/CVE-2020-18899/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-18899
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-18899
- OSV: https://osv.dev/vulnerability/CVE-2020-18899

---
From sbomify Insights: https://insights.sbomify.com/CVE-2020-18899/
Summaries are generated and may contain mistakes; the official description above is the record.