# CVE-2018-20349: Null dereference in n/a

> Attackers can cause a denial of service via application crash in the igraph library by exploiting a NULL pointer dereference in the string difference function.

- **Severity:** Medium 6.5 (`CVSS:3.0/AV:N/AC:L/PR:N/UI:R/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:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 22 Dec 2018
- **Updated:** 5 Aug 2024
- **Also known as:** DEBIAN-CVE-2018-20349, DLA-2055-1, GHSA-qgqh-phj7-7fm4, MGASA-2020-0013, RSEC-2023-4, UBUNTU-CVE-2018-20349, USN-4644-1

## What is CVE-2018-20349?

CVE-2018-20349 is a medium-severity vulnerability in n/a, published on 22 Dec 2018. 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

The igraph_i_strdiff function in igraph_trie.c in igraph through 0.7.1 has an NULL pointer dereference that allows attackers to cause a denial of service (application crash) via a crafted object.

Weakness: CWE-476 (NULL Pointer Dereference)

## Which versions are affected by CVE-2018-20349?

1 open source package ship an affected version, including igraph. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `igraph` | CRAN | From 0.7.1 | 1.2.2-2 |

Products: Igraph Igraph.

## How do I fix CVE-2018-20349?

Upgrade igraph to 1.2.2-2 or later.

## Is CVE-2018-20349 being exploited?

There is no known exploitation of CVE-2018-20349 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2018-20349 and fix it if it is affected.

What it is: CVE-2018-20349 is a medium-severity vulnerability in n/a, published on 22 Dec 2018. 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-2018-20349 in the wild and no public exploit code.

Affected packages and fixed versions:
- igraph (CRAN): affected from 0.7.1; fixed in 1.2.2-2

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-2018-20349/ (Markdown: https://insights.sbomify.com/CVE-2018-20349/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2018-20349
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2018-20349
- OSV: https://osv.dev/vulnerability/CVE-2018-20349

---
From sbomify Insights: https://insights.sbomify.com/CVE-2018-20349/
Summaries are generated and may contain mistakes; the official description above is the record.