# CVE-2026-102633: libexpat 2.7.2 through 2.8.5 Integer Overflow in expat_realloc

> Attackers can cause memory corruption or denial of service via malicious XML due to an integer overflow in libexpat's reallocation logic on 32-bit systems.

- **Severity:** High 8.2 (`CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 29 Sep 2026
- **Updated:** 29 Sep 2026
- **Also known as:** ALPINE-CVE-2026-102633, AZL-105048, BELL-CVE-2026-102633, CLSA-2026-1791196479, CLSA-2026-1791791753, DEBIAN-CVE-2026-102633, ECHO-c3aa-d0c7-eaa9, GHSA-533f-rf84-jgcc, UBUNTU-CVE-2026-102633

## What is CVE-2026-102633?

CVE-2026-102633 is a high-severity vulnerability in libexpat, published on 29 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

libexpat versions 2.7.2 through 2.8.5 contain an integer overflow vulnerability in expat_realloc() function on 32-bit platforms when computing allocation sizes. Attackers supplying malicious XML to applications parsing with vulnerable libexpat can cause heap buffer overflow, memory corruption, or denial of service.

Weakness: CWE-190 (Integer Overflow or Wraparound)

## Which versions are affected by CVE-2026-102633?


## How do I fix CVE-2026-102633?

Upgrade to a fixed version.

## Is CVE-2026-102633 being exploited?

There is no known exploitation of CVE-2026-102633 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-102633 and fix it if it is affected.

What it is: CVE-2026-102633 is a high-severity vulnerability in libexpat, published on 29 Sep 2026. 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-2026-102633 in the wild and no public exploit code.

Affected product: libexpat. 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-2026-102633/ (Markdown: https://insights.sbomify.com/CVE-2026-102633/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-102633
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-102633
- OSV: https://osv.dev/vulnerability/CVE-2026-102633

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-102633/
Summaries are generated and may contain mistakes; the official description above is the record.