# CVE-2026-44983: smallbitvec: Safe API Triggered Heap Buffer Overflow via Integer Overflow

> An integer overflow in smallbitvec causes heap buffer overflows via safe APIs, potentially allowing memory corruption or crashes.

- **Severity:** High 7.3 (`CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 26 May 2026
- **Updated:** 27 May 2026
- **Also known as:** DEBIAN-CVE-2026-44983, GHSA-97wc-2hqc-cjgr, UBUNTU-CVE-2026-44983

## What is CVE-2026-44983?

CVE-2026-44983 is a high-severity vulnerability in servo smallbitvec, published on 26 May 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

smallbitvec is a growable bit-vector for Rust, optimized for size. From 1.0.1 to 2.6.0, an integer overflow in the internal capacity calculation of smallbitvec can lead to an undersized heap allocation, resulting in a heap buffer overflow through safe APIs only. This allows memory corruption without requiring unsafe code from the caller. This vulnerability is fixed in 2.6.1.

Weakness: CWE-190 (Integer Overflow or Wraparound), CWE-122 (Heap-based Buffer Overflow)

## Which versions are affected by CVE-2026-44983?

2 open source packages ship an affected version, including smallbitvec.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `smallbitvec` | crates.io | From 1.0.1 to 2.6.0 | None |
| `smallbitvec` | crates.io | From 1.0.1 to 2.6.0 | None |

## How do I fix CVE-2026-44983?

Upgrade to a fixed version.

## Is CVE-2026-44983 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-44983 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-44983 and fix it if it is affected.

What it is: CVE-2026-44983 is a high-severity vulnerability in servo smallbitvec, published on 26 May 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-44983 exists.

Affected packages and fixed versions:
- smallbitvec (crates.io): affected from 1.0.1 up to 2.6.0; no fix listed
- smallbitvec (crates.io): affected from 1.0.1 up to 2.6.0; no fix listed

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-2026-44983/ (Markdown: https://insights.sbomify.com/CVE-2026-44983/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-44983
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-44983
- OSV: https://osv.dev/vulnerability/CVE-2026-44983

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-44983/
Summaries are generated and may contain mistakes; the official description above is the record.