CVE-2021-21235 is a medium-severity (CVSS 6.5) Uncontrolled Resource Consumption vulnerability in kamadak-exif. A fix is available for kamadak-exif — see the affected versions and patch details below.
kamadak-exif vulnerable to Infinite loop when parsing PNG files
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
CVE-2021-21235 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 376,715 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
kamadak-exifReal-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
kamadak-exif is an exif parsing library written in pure Rust. In kamadak-exif version 0.5.2, there is an infinite loop in parsing crafted PNG files. Specifically, reader::read_from_container can cause an infinite loop when a crafted PNG file is given. This is fixed in version 0.5.3. No workaround is available. Applications that do not pass files with the PNG signature to Reader::read_from_container are not affected.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🦀crates.io | kamadak-exif | ≥ 0.5.2&&< 0.5.3 | 0.5.3cargo update -p kamadak-exif --precise 0.5.3 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for kamadak-exif, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update kamadak-exif to 0.5.3 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-21235 is resolved across your whole dependency graph.
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.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2021-21235 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2021-21235. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2021-21235 in your dependencies?
O3 Security finds CVE-2021-21235 across crates.io dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.