# CVE-2021-3881: Out-of-bounds Read in bfabiszewski/libmobi

> An out-of-bounds read in libmobi allows attackers to cause denial of service or disclose sensitive memory contents.

- **Severity:** High 7.1 (`CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:L`)
- **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:** No
- **Published:** 15 Oct 2021
- **Updated:** 3 Aug 2024
- **Also known as:** GHSA-wp4m-4w7q-mqpj

## What is CVE-2021-3881?

CVE-2021-3881 is a high-severity memory corruption vulnerability in bfabiszewski/libmobi, published on 15 Oct 2021. 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

libmobi is vulnerable to Out-of-bounds Read

Weakness: CWE-125 (Out-of-bounds Read)

## Which versions are affected by CVE-2021-3881?

It affects 1 product.


Products: Libmobi Project Libmobi.

## How do I fix CVE-2021-3881?

No fix has been published for CVE-2021-3881 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-3881 being exploited?

There is no known exploitation of CVE-2021-3881 in the wild and no public exploit code.

## Other vulnerabilities in bfabiszewski/libmobi

- [CVE-2021-3751](https://insights.sbomify.com/CVE-2021-3751/): Out-of-bounds Write in bfabiszewski/libmobi (critical 9.6)
- [CVE-2018-11724](https://insights.sbomify.com/CVE-2018-11724/): Memory corruption in n/a (high 8.8)
- [CVE-2018-11726](https://insights.sbomify.com/CVE-2018-11726/): Memory corruption in n/a (high 8.8)
- [CVE-2018-11438](https://insights.sbomify.com/CVE-2018-11438/): Memory corruption in n/a (high 8.8)
- [CVE-2021-3888](https://insights.sbomify.com/CVE-2021-3888/): Use of Out-of-range Pointer Offset in bfabiszewski/libmobi (high 7.1)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-3881 and fix it if it is affected.

What it is: CVE-2021-3881 is a high-severity memory corruption vulnerability in bfabiszewski/libmobi, published on 15 Oct 2021. 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-2021-3881 in the wild and no public exploit code.

Affected product: bfabiszewski/libmobi. 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-2021-3881/ (Markdown: https://insights.sbomify.com/CVE-2021-3881/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-3881
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-3881
- OSV: https://osv.dev/vulnerability/CVE-2021-3881

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From sbomify Insights: https://insights.sbomify.com/CVE-2021-3881/
Summaries are generated and may contain mistakes; the official description above is the record.