# CVE-2021-31826: Null dereference in n/a

> A crafted cookie can trigger a NULL pointer dereference in Shibboleth Service Provider, causing a daemon crash and denial of service.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 27 Apr 2021
- **Updated:** 3 Aug 2024
- **Also known as:** DEBIAN-CVE-2021-31826, DSA-4905-1, GHSA-rqpx-m7mv-mxxf, UBUNTU-CVE-2021-31826

## What is CVE-2021-31826?

CVE-2021-31826 is a high-severity vulnerability in n/a, published on 27 Apr 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Shibboleth Service Provider 3.x before 3.2.2 is prone to a NULL pointer dereference flaw involving the session recovery feature. The flaw is exploitable (for a daemon crash) on systems not using this feature if a crafted cookie is supplied.

Weakness: CWE-476 (NULL Pointer Dereference)

## Which versions are affected by CVE-2021-31826?

It affects 1 product.


Products: Shibboleth Service Provider.

## How do I fix CVE-2021-31826?

Upgrade to a fixed version.

## Is CVE-2021-31826 being exploited?

There is no known exploitation of CVE-2021-31826 in the wild and no public exploit code.

## Other vulnerabilities in n/a

- [CVE-2019-19191](https://insights.sbomify.com/CVE-2019-19191/): Privilege escalation in n/a (high 7.8)
- [CVE-2023-22947](https://insights.sbomify.com/CVE-2023-22947/): Privilege escalation in n/a (high 7.3)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-31826 and fix it if it is affected.

What it is: CVE-2021-31826 is a high-severity vulnerability in n/a, published on 27 Apr 2021. 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-2021-31826 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-2021-31826/ (Markdown: https://insights.sbomify.com/CVE-2021-31826/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-31826
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-31826
- OSV: https://osv.dev/vulnerability/CVE-2021-31826

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-31826/
Summaries are generated and may contain mistakes; the official description above is the record.