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VulnerabilityPublished

CVE-2026-44983: servo smallbitvec · Heap-based Buffer Overflow

Affects servo smallbitvecSource CVE Database V5

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Not known to be exploited · CVSS 7.3 High : upgrade to 2.6.1 soon.

Data as of 30 Oct 2026, 11:52 UTC

CVSS 3.1 base score
7.3High
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.1% chance of exploitation in 30 days – higher than 4% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 2.6.1
CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 26 May 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 30 Oct 2026.

What to do

Upgrade smallbitvec and github/servo/smallbitvec to 2.6.1.

Affected software

ProductAffectedFixed in
servosmallbitvecAffected
  • >=1.0.1 <2.6.1
Fixed in
  • 2.6.1
crates.iogithub/servo/smallbitvecpkg:cargo/github/servo/smallbitvecOther threatsAffected
  • =1.0.1
  • >=1.0.1 <2.6.1
Fixed in
  • 2.6.1

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

Upgrade 'smallbitvec' to version 2.6.1 or later, where this vulnerability is fixed. Since this is a library vulnerability, users should update their dependencies accordingly. No vendor advisory is provided to indicate alternative mitigations or temporary fixes. Patch status is confirmed by the version fix information in the description.

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.

References

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