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Not in CISA KEV
HIGH severity

CVE-2021-28307 — fltk

HIGH

CVE-2021-28307 is a high-severity (CVSS 7.5) NULL Pointer Dereference vulnerability in fltk. A fix is available for fltk — see the affected versions and patch details below.

Null pointer deference in fltk

Also known asCVE-2021-28306CVE-2021-28308GHSA-5pg8-h4gv-m3p8GHSA-7qcc-g2m9-8533GHSA-vjmg-pc8h-p6p8RUSTSEC-2021-0038
Published
Updated
Affected
1 pkg
Patched
1 / 1
Exploits
None indexed
Exploitation data as of Oct 9, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗
1.1%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs65th percentile — riskier than 65% of all scored CVEsHighest risk
0.00%0.54%1.09%1.63%0.3%1.1%Apr 26Aug 26Oct 26

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

CVE-2021-28307 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.

Where this sits among everything scored

Of 385,386 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.

Real-World Exposure

1 pkg affected
🦀fltk

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects crates.io packages — download data is not available via public APIs for these ecosystems.

Description

An issue was discovered in the fltk crate before 0.15.3 for Rust. There is a NULL pointer dereference during attempted use of a multi label type if the image is nonexistent.

Affected Packages

1 total 1 fixed
EcosystemPackageVulnerable rangeFix
🦀crates.iofltkall versions0.15.3cargo update -p fltk --precise 0.15.3

Affected Products

1 product · 1 configurations
Application
fltkfltk_project
< 0.15.3
range

Detection & mitigation playbook

Open-source dependency

  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for fltk, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Fix

    Update fltk to 0.15.3 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-28307 is resolved across your whole dependency graph.

  3. Workarounds

    If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Frequently Asked Questions

An issue was discovered in the fltk crate before 0.15.3 for Rust. There is a NULL pointer dereference during attempted use of a multi label type if the image is nonexistent.
O3 Security · Impact-Aware SCA

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CVE-2021-28307: fltk — Fixed in 0.15.3