# CVE-2019-20838: Memory corruption in n/a

> A buffer over-read in the PCRE library's JIT compiler can cause crashes or leak memory when processing specific regex patterns.

- **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:** 15 Jun 2020
- **Updated:** 8 Oct 2026
- **Also known as:** DEBIAN-CVE-2019-20838, GHSA-689f-qv4w-xgqf, JLSEC-2026-176, UBUNTU-CVE-2019-20838

## What is CVE-2019-20838?

CVE-2019-20838 is a high-severity memory corruption vulnerability in Apple Macos, published on 15 Jun 2020. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

libpcre in PCRE before 8.43 allows a subject buffer over-read in JIT when UTF is disabled, and \X or \R has more than one fixed quantifier, a related issue to CVE-2019-20454.

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

## Which versions are affected by CVE-2019-20838?

It affects 3 products.


Products: Apple Macos, Pcre Pcre, Splunk Universal Forwarder.

## How do I fix CVE-2019-20838?

Upgrade to a fixed version.

## Is CVE-2019-20838 being exploited?

There is no known exploitation of CVE-2019-20838 in the wild and no public exploit code.

## Other vulnerabilities in Apple Macos

- [CVE-2026-65400](https://insights.sbomify.com/CVE-2026-65400/): Apple macOS Improper Authentication (critical 9.8, exploited in the wild)
- [CVE-2024-44146](https://insights.sbomify.com/CVE-2024-44146/): Security feature bypass in macOS (critical 10.0)
- [CVE-2024-44148](https://insights.sbomify.com/CVE-2024-44148/): Security feature bypass in macOS (critical 10.0)
- [CVE-2023-38586](https://insights.sbomify.com/CVE-2023-38586/): Security feature bypass in macOS (critical 10.0)
- [CVE-2023-40455](https://insights.sbomify.com/CVE-2023-40455/): Security feature bypass in macOS (critical 10.0)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2019-20838 and fix it if it is affected.

What it is: CVE-2019-20838 is a high-severity memory corruption vulnerability in Apple Macos, published on 15 Jun 2020. 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-2019-20838 in the wild and no public exploit code.

Affected product: Apple Macos. 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-2019-20838/ (Markdown: https://insights.sbomify.com/CVE-2019-20838/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2019-20838
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2019-20838
- OSV: https://osv.dev/vulnerability/CVE-2019-20838

---
From sbomify Insights: https://insights.sbomify.com/CVE-2019-20838/
Summaries are generated and may contain mistakes; the official description above is the record.