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CRITICAL severity

CVE-2021-28308 — fltk

CRITICAL

CVE-2021-28308 is a critical-severity (CVSS 9.1) Out-of-bounds Read 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-2021-28307GHSA-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 7, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗
1.3%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs69th percentile — riskier than 69% of all scored CVEsHighest risk
0.00%0.59%1.19%1.78%0.4%1.3%Apr 26Aug 26Oct 26

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

How urgent is this, really

CVE-2021-28308 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.

Where this sits among everything scored

Of 385,738 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-2021-28308 is resolved across your whole dependency graph.

  3. Workarounds

    Stop feeding it untrusted input: reject or quarantine files and payloads from unverified sources until you can upgrade, restrict accepted formats to the ones you actually need, and run the parsing or decoding step in a least-privileged sandbox or short-lived worker so a crash or corrupted read cannot reach the rest of the process.

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-2021-28308: fltk — Fixed in 0.15.3