# CVE-2021-4076: Information disclosure in tang

> A flaw in the tang server allows attackers to leak private keys, compromising cryptographic security.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 2 Mar 2022
- **Updated:** 3 Aug 2024
- **Also known as:** DEBIAN-CVE-2021-4076, DSA-5025-1, GHSA-83f4-c2vq-g2p3

## What is CVE-2021-4076?

CVE-2021-4076 is a high-severity vulnerability in tang, published on 2 Mar 2022. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

A flaw exists in tang, a network-based cryptographic binding server, which could result in leak of private keys.

Weakness: CWE-200 (Exposure of Sensitive Information to an Unauthorized Actor)

## Which versions are affected by CVE-2021-4076?

It affects 1 product.


Products: Tang Project Tang.

## How do I fix CVE-2021-4076?

Apply the vendor's patch.

## Is CVE-2021-4076 being exploited?

There is no known exploitation of CVE-2021-4076 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-4076 and fix it if it is affected.

What it is: CVE-2021-4076 is a high-severity vulnerability in tang, published on 2 Mar 2022. 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-2021-4076 in the wild and no public exploit code.

Affected product: tang. 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-2021-4076/ (Markdown: https://insights.sbomify.com/CVE-2021-4076/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-4076
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-4076
- OSV: https://osv.dev/vulnerability/CVE-2021-4076

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-4076/
Summaries are generated and may contain mistakes; the official description above is the record.