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Fencer Vulns
high 7.3

CVE-2026-44983 json

smallbitvec: Safe API Triggered Heap Buffer Overflow via Integer Overflow

published 2026-05-09 6 mo ago modified 2026-07-24 3 mo ago also GHSA-97wc-2hqc-cjgr , EUVD-2026-32015

cvss
7.3
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 4%
public exploits
0
none known

Summary

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.

Patch / fix

  • rust-smallbitvec Debian 14 2.6.1-1

debian advisories DEBIAN-CVE-2026-44983

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-44983 updated cvss 7.3

smallbitvec: smallbitvec: Memory corruption via integer overflow in capacity calculation

  • Red Hat Enterprise Linux 9 firefox, firefox-x11, thunderbird, firefox 140.15.0-1.el10_2, thunderbird 140.14.0-1.el10_2 Red Hat Enterprise Linux 10 firefox 140.15.0-1.el10_2, tree-sitter 0.23.0-3.el10, thunderbird 140.14.0-1.el10_2
    affected: workaround, no fix available “Red Hat has investigated whether a possible mitigation exists for this issue, and has not been able to identify a practical example. Please update the affected package as soon as possible.”
  • Red Hat Enterprise Linux 7 firefox, firefox 140.15.0-1.el10_2 Red Hat Enterprise Linux 8 firefox, mozjs60, thunderbird, firefox 140.15.0-1.el10_2, thunderbird 140.14.0-1.el10_2 Red Hat Enterprise Linux 9 gjs Red Hat Enterprise Linux 10 gjs
    under investigation

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
Proof of concept is public
Automatable
no
Technical impact
partial
Assessed
5 mo ago

Exploit prediction

0.15% chance of exploitation in the next 30 days, higher than 4% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/servo/smallbitvec/security/advisories/GHSA-97wc-2hqc-cjgr referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 7.3 CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:H
GitHub 3.1 7.3 CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:H

Affected packages

ecosystem package affected fixed in
crates.io smallbitvec
>=1.0.1, <=2.6.0
 no fix listed

Affected products

  • servo smallbitvec

Classification

Weakness
  • CWE-122 Heap-based Buffer Overflow
  • CWE-190 Integer Overflow or Wraparound

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.