# CVE-2016-9121: Elliptic Curve Key Disclosure in go-jose

> An attacker can exploit an invalid curve attack in ECDH-ES key derivation to potentially decrypt messages, affecting users of the Go JOSE library.

- **Severity:** Critical 9.1 (`CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/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:** 28 Mar 2017
- **Updated:** 6 Aug 2024
- **Also known as:** DEBIAN-CVE-2016-9121, GHSA-86r9-39j9-99wp, GO-2020-0010

## What is CVE-2016-9121?

CVE-2016-9121 is a critical vulnerability in Go JOSE All versions before 1.0.4, published on 28 Mar 2017. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

go-jose before 1.0.4 suffers from an invalid curve attack for the ECDH-ES algorithm. When deriving a shared key using ECDH-ES for an encrypted message, go-jose neglected to check that the received public key on a message is on the same curve as the static private key of the receiver, thus making it vulnerable to an invalid curve attack.

Weakness: CWE-326 (Inadequate Encryption Strength)

## Which versions are affected by CVE-2016-9121?

5 open source packages ship an affected version, including github.com/square/go-jose and gopkg.in/square/go-jose.v1. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `github.com/square/go-jose` | Go | All versions | 1.0.4 |
| `github.com/square/go-jose` | Go | All versions | 1.0.4 |
| `github.com/square/go-jose` | Go | All versions | 1.0.4 |
| `gopkg.in/square/go-jose.v1` | Go | All versions | 1.0.4 |
| `gopkg.in/square/go-jose.v1` | Go | All versions | 1.0.4 |

Products: Go-Jose Project Go-Jose.

## How do I fix CVE-2016-9121?

Upgrade github.com/square/go-jose to 1.0.4 or later.

## Is CVE-2016-9121 being exploited?

There is no known exploitation of CVE-2016-9121 in the wild and no public exploit code.

## Other vulnerabilities in Go JOSE All versions before 1.0.4

- [CVE-2026-34986](https://insights.sbomify.com/CVE-2026-34986/): Go JOSE affect by a panic in JWE decryption (high 7.5)
- [CVE-2016-9122](https://insights.sbomify.com/CVE-2016-9122/): Go JOSE Signature Validation Bypass (high 7.5)
- [CVE-2016-9123](https://insights.sbomify.com/CVE-2016-9123/): Integer Overflow in go-jose (high 7.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2016-9121 and fix it if it is affected.

What it is: CVE-2016-9121 is a critical vulnerability in Go JOSE All versions before 1.0.4, published on 28 Mar 2017. 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-2016-9121 in the wild and no public exploit code.

Affected packages and fixed versions:
- github.com/square/go-jose (Go): affected all versions; fixed in 1.0.4
- github.com/square/go-jose (Go): affected all versions; fixed in 1.0.4
- github.com/square/go-jose (Go): affected all versions; fixed in 1.0.4
- gopkg.in/square/go-jose.v1 (Go): affected all versions; fixed in 1.0.4
- gopkg.in/square/go-jose.v1 (Go): affected all versions; fixed in 1.0.4

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-2016-9121/ (Markdown: https://insights.sbomify.com/CVE-2016-9121/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2016-9121
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2016-9121
- OSV: https://osv.dev/vulnerability/CVE-2016-9121

---
From sbomify Insights: https://insights.sbomify.com/CVE-2016-9121/
Summaries are generated and may contain mistakes; the official description above is the record.