# CVE-2020-13895: Other in n/a

> The Crypt::Perl library fails to properly verify ECDSA signatures with small r/s values, potentially allowing signature verification bypass.

- **Severity:** High 8.8 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/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:** No
- **Published:** 7 Jun 2020
- **Updated:** 4 Aug 2024
- **Also known as:** GHSA-jxxc-m3fj-q52w

## What is CVE-2020-13895?

CVE-2020-13895 is a high-severity vulnerability in n/a, published on 7 Jun 2020. 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

Crypt::Perl::ECDSA in the Crypt::Perl (aka p5-Crypt-Perl) module before 0.32 for Perl fails to verify correct ECDSA signatures when r and s are small and when s = 1. This happens when using the curve secp256r1 (prime256v1). This could conceivably have a security-relevant impact if an attacker wishes to use public r and s values when guessing whether signature verification will fail.

Weakness: CWE-347 (Improper Verification of Cryptographic Signature)

## Which versions are affected by CVE-2020-13895?

It affects 1 product.


Products: P5-Crypt-Perl Project P5-Crypt-Perl.

## How do I fix CVE-2020-13895?

No fix has been published for CVE-2020-13895 yet. Limit exposure of the affected software until one is available.

## Is CVE-2020-13895 being exploited?

There is no known exploitation of CVE-2020-13895 in the wild and no public exploit code.

## Other vulnerabilities in n/a

- [CVE-2020-17478](https://insights.sbomify.com/CVE-2020-17478/): Information disclosure in n/a (high 7.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2020-13895 and fix it if it is affected.

What it is: CVE-2020-13895 is a high-severity vulnerability in n/a, published on 7 Jun 2020. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2020-13895 in the wild and no public exploit code.

Affected product: n/a. 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-2020-13895/ (Markdown: https://insights.sbomify.com/CVE-2020-13895/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-13895
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-13895
- OSV: https://osv.dev/vulnerability/CVE-2020-13895

---
From sbomify Insights: https://insights.sbomify.com/CVE-2020-13895/
Summaries are generated and may contain mistakes; the official description above is the record.