# CVE-2015-20109: Denial of service in n/a

> Attackers can cause application crashes in glibc via crafted fnmatch patterns, requiring updates to the GNU C Library.

- **Severity:** Medium 5.5 (`CVSS:3.1/AV:L/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:** Local or same network only
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 25 Jun 2023
- **Updated:** 27 Nov 2024
- **Also known as:** DEBIAN-CVE-2015-20109, GHSA-rf48-x9gm-3vx2, UBUNTU-CVE-2015-20109

## What is CVE-2015-20109?

CVE-2015-20109 is a medium-severity denial of service vulnerability in Gnu Glibc, published on 25 Jun 2023. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.

### Official description

end_pattern (called from internal_fnmatch) in the GNU C Library (aka glibc or libc6) before 2.22 might allow context-dependent attackers to cause a denial of service (application crash), as demonstrated by use of the fnmatch library function with the **(!() pattern. NOTE: this is not the same as CVE-2015-8984; also, some Linux distributions have fixed CVE-2015-8984 but have not fixed this additional fnmatch issue.

Weakness: CWE-120 (Buffer Copy without Checking Size of Input)

## Which versions are affected by CVE-2015-20109?

It affects 1 product.


Products: Gnu Glibc.

## How do I fix CVE-2015-20109?

Apply the vendor's patch.

## Is CVE-2015-20109 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2015-20109 exists.

## Other vulnerabilities in Gnu Glibc

- [CVE-2026-5450](https://insights.sbomify.com/CVE-2026-5450/): scanf %mc off-by-one heap buffer overflow (critical 9.8)
- [CVE-2023-25139](https://insights.sbomify.com/CVE-2023-25139/): Memory corruption in n/a (critical 9.8)
- [CVE-1999-0199](https://insights.sbomify.com/CVE-1999-0199/): Other in n/a (critical 9.8)
- [CVE-2019-1010022](https://insights.sbomify.com/CVE-2019-1010022/): Security feature bypass in glibc (critical 9.8)
- [CVE-2005-3590](https://insights.sbomify.com/CVE-2005-3590/): Memory corruption in n/a (critical 9.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2015-20109 and fix it if it is affected.

What it is: CVE-2015-20109 is a medium-severity denial of service vulnerability in Gnu Glibc, published on 25 Jun 2023. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2015-20109 exists.

Affected product: Gnu Glibc. 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-2015-20109/ (Markdown: https://insights.sbomify.com/CVE-2015-20109/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2015-20109
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2015-20109
- OSV: https://osv.dev/vulnerability/CVE-2015-20109

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From sbomify Insights: https://insights.sbomify.com/CVE-2015-20109/
Summaries are generated and may contain mistakes; the official description above is the record.