# CVE-2018-12896: Integer overflow in n/a

> A local attacker can cause a denial of service via integer overflow in POSIX timer accounting using crafted system calls.

- **Severity:** Medium 5.5 (`CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 2 Jul 2018
- **Updated:** 5 Aug 2024
- **Also known as:** DEBIAN-CVE-2018-12896, GHSA-752f-2m5c-7473, UBUNTU-CVE-2018-12896

## What is CVE-2018-12896?

CVE-2018-12896 is a medium-severity vulnerability in Canonical Ubuntu Linux, published on 2 Jul 2018. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

An issue was discovered in the Linux kernel through 4.17.3. An Integer Overflow in kernel/time/posix-timers.c in the POSIX timer code is caused by the way the overrun accounting works. Depending on interval and expiry time values, the overrun can be larger than INT_MAX, but the accounting is int based. This basically makes the accounting values, which are visible to user space via timer_getoverrun(2) and siginfo::si_overrun, random. For example, a local user can cause a denial of service (signed integer overflow) via crafted mmap, futex, timer_create, and timer_settime system calls.

Weakness: CWE-190 (Integer Overflow or Wraparound)

## Which versions are affected by CVE-2018-12896?

It affects 3 products.


Products: Canonical Ubuntu Linux, Debian Debian Linux, Linux kernel.

## How do I fix CVE-2018-12896?

Apply the vendor's patch.

## Is CVE-2018-12896 being exploited?

There is no known exploitation of CVE-2018-12896 in the wild and no public exploit code.

## Other vulnerabilities in Canonical Ubuntu Linux

- [CVE-2020-11651](https://insights.sbomify.com/CVE-2020-11651/): SaltStack Salt Authentication Bypass (critical 9.8, exploited in the wild)
- [CVE-2020-7247](https://insights.sbomify.com/CVE-2020-7247/): OpenSMTPD Remote Code Execution (critical 9.8, exploited in the wild)
- [CVE-2019-16928](https://insights.sbomify.com/CVE-2019-16928/): Exim Out-of-bounds Write (critical 9.8, exploited in the wild)
- [CVE-2018-6789](https://insights.sbomify.com/CVE-2018-6789/): Exim Buffer Overflow (critical 9.8, exploited in the wild)
- [CVE-2015-2590](https://insights.sbomify.com/CVE-2015-2590/): Oracle Java SE and Java SE Embedded Remote Code Execution (critical 9.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2018-12896 and fix it if it is affected.

What it is: CVE-2018-12896 is a medium-severity vulnerability in Canonical Ubuntu Linux, published on 2 Jul 2018. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2018-12896 in the wild and no public exploit code.

Affected product: Canonical Ubuntu Linux. 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-2018-12896/ (Markdown: https://insights.sbomify.com/CVE-2018-12896/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2018-12896
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2018-12896
- OSV: https://osv.dev/vulnerability/CVE-2018-12896

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From sbomify Insights: https://insights.sbomify.com/CVE-2018-12896/
Summaries are generated and may contain mistakes; the official description above is the record.