# CVE-2020-26244: Cryptographic issues in Python oic

> Attackers can bypass OpenID Connect authentication checks due to missing signature verification and algorithm validation in the Python oic library.

- **Severity:** Medium 6.8 (`CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 2 Dec 2020
- **Updated:** 4 Aug 2024
- **Also known as:** GHSA-4fjv-pmhg-3rfg, PYSEC-2020-69, openSUSE-SU-2024:11244-1, openSUSE-SU-2024:14150-1, openSUSE-SU-2026:12021-1

## What is CVE-2020-26244?

CVE-2020-26244 is a medium-severity vulnerability in OpenIDC pyoidc, published on 2 Dec 2020. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

Python oic is a Python OpenID Connect implementation. In Python oic before version 1.2.1, there are several related cryptographic issues affecting client implementations that use the library. The issues are: 1) The IdToken signature algorithm was not checked automatically, but only if the expected algorithm was passed in as a kwarg. 2) JWA `none` algorithm was allowed in all flows. 3) oic.consumer.Consumer.parse_authz returns an unverified IdToken. The verification of the token was left to the discretion of the implementator. 4) iat claim was not checked for sanity (i.e. it could be in the future). These issues are patched in version 1.2.1.

Weakness: CWE-347 (Improper Verification of Cryptographic Signature), CWE-325 (Missing Cryptographic Step)

## Which versions are affected by CVE-2020-26244?

3 open source packages ship an affected version, including oic. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `oic` | PyPI | All versions | 1.2.1 |
| `oic` | PyPI | All versions | 1.2.1 |
| `oic` | PyPI | All versions | 1.2.1 |
| `python-oic` | openSUSE:Tumbleweed | All versions | 1.5.0-1.8 |
| `python-oic` | openSUSE:Tumbleweed | All versions | 1.7.0-2.4 |

Products: Python Openid Connect Project Python Openid Connect.

## How do I fix CVE-2020-26244?

Upgrade oic to 1.2.1 or later.

## Is CVE-2020-26244 being exploited?

There is no known exploitation of CVE-2020-26244 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2020-26244 and fix it if it is affected.

What it is: CVE-2020-26244 is a medium-severity vulnerability in OpenIDC pyoidc, published on 2 Dec 2020. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2020-26244 in the wild and no public exploit code.

Affected packages and fixed versions:
- oic (PyPI): affected all versions; fixed in 1.2.1
- oic (PyPI): affected all versions; fixed in 1.2.1
- oic (PyPI): affected all versions; fixed in 1.2.1

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-2020-26244/ (Markdown: https://insights.sbomify.com/CVE-2020-26244/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-26244
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-26244
- OSV: https://osv.dev/vulnerability/CVE-2020-26244

---
From sbomify Insights: https://insights.sbomify.com/CVE-2020-26244/
Summaries are generated and may contain mistakes; the official description above is the record.