# CVE-2019-14853: Duplicate Advisory: possible DoS caused by malformed signature decoding in Pure-Python ECDSA

> Attackers can cause a denial of service in applications using the python-ecdsa library by submitting malformed DER signatures that trigger unexpected exceptions.

- **Severity:** Low 3.7 (`CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 26 Nov 2019
- **Updated:** 5 Aug 2024
- **Also known as:** DEBIAN-CVE-2019-14853, GHSA-2mrj-435v-c2cr, GHSA-pwfw-mgfj-7g3g, PYSEC-2019-177, UBUNTU-CVE-2019-14853

## What is CVE-2019-14853?

CVE-2019-14853 is a low-severity denial of service vulnerability in [UNKNOWN] python-ecdsa, published on 26 Nov 2019. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

An error-handling flaw was found in python-ecdsa before version 0.13.3. During signature decoding, malformed DER signatures could raise unexpected exceptions (or no exceptions at all), which could lead to a denial of service.

Weakness: CWE-755 (Improper Handling of Exceptional Conditions), CWE-391 (DEPRECATED: Unchecked Error Condition)

## Which versions are affected by CVE-2019-14853?

5 open source packages ship an affected version, including ecdsa. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `ecdsa` | PyPI | All versions | 0.13.3 |
| `ecdsa` | PyPI | All versions | 0.13.3 |
| `ecdsa` | PyPI | All versions | 0.13.3 |
| `ecdsa` | PyPI | All versions | 0.13.3 |
| `ecdsa` | PyPI | All versions | 0.13.3 |

Products: Python-Ecdsa Project Python-Ecdsa.

## How do I fix CVE-2019-14853?

Upgrade ecdsa to 0.13.3 or later.

## Is CVE-2019-14853 being exploited?

There is no known exploitation of CVE-2019-14853 in the wild and no public exploit code.

## Other vulnerabilities in [UNKNOWN] python-ecdsa

- [CVE-2019-14859](https://insights.sbomify.com/CVE-2019-14859/): Improper Verification of Cryptographic Signature in Pure-Python ECDSA (high 7.4)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2019-14853 and fix it if it is affected.

What it is: CVE-2019-14853 is a low-severity denial of service vulnerability in [UNKNOWN] python-ecdsa, published on 26 Nov 2019. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2019-14853 in the wild and no public exploit code.

Affected packages and fixed versions:
- ecdsa (PyPI): affected all versions; fixed in 0.13.3
- ecdsa (PyPI): affected all versions; fixed in 0.13.3
- ecdsa (PyPI): affected all versions; fixed in 0.13.3
- ecdsa (PyPI): affected all versions; fixed in 0.13.3
- ecdsa (PyPI): affected all versions; fixed in 0.13.3

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-2019-14853/ (Markdown: https://insights.sbomify.com/CVE-2019-14853/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2019-14853
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2019-14853
- OSV: https://osv.dev/vulnerability/CVE-2019-14853

---
From sbomify Insights: https://insights.sbomify.com/CVE-2019-14853/
Summaries are generated and may contain mistakes; the official description above is the record.