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Vulnerability · Published May 26, 2026 · Assigned by GitHub_M

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

High 7.3

In plain English

A high-severity heap buffer overflow in smallbitvec from servo. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 4% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)7.3High
Exploit odds (30 days)0.2%top 95.7% of all CVEs
Exploited in the wildNo reportsCISA SSVC: poc
Attack toolingNoneno public tooling known

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.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
Debian:12rust-smallbitvecno fix listedDEBIAN-CVE-2026-44983
Debian:13rust-smallbitvecno fix listedDEBIAN-CVE-2026-44983
Debian:14rust-smallbitvec2.6.1-1DEBIAN-CVE-2026-44983
Ubuntu:22.04:LTSrust-smallbitvecno fix listedUBUNTU-CVE-2026-44983
Ubuntu:24.04:LTSrust-smallbitvecno fix listedUBUNTU-CVE-2026-44983
Ubuntu:25.10rust-smallbitvecno fix listedUBUNTU-CVE-2026-44983
Ubuntu:26.04:LTSrust-smallbitvecno fix listedUBUNTU-CVE-2026-44983
Ubuntu:26.10rust-smallbitvecno fix listedUBUNTU-CVE-2026-44983

Affected products (as reported)

VendorProductVersions
servo smallbitvec >= 1.0.1, < 2.6.1

Weakness: CWE-122, CWE-190 · Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:H

References