CVE-2018-1000883 is a medium-severity (CVSS 6.5) Improper Input Validation vulnerability in plug. A fix is available for plug — see the affected versions and patch details below.
Header Injection
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-2018-1000883 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 378,156 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
plug💧plug💧plug💧plugReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Hex packages — download data is not available via public APIs for these ecosystems.
Description
Elixir Plug Plug version All contains a Header Injection vulnerability in Connection that can result in Given a cookie value, Headers can be added. This attack appear to be exploitable via Crafting a value to be sent as a cookie. This vulnerability appears to have been fixed in >= 1.3.5 or ~> 1.2.5 or ~> 1.1.9 or ~> 1.0.6.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 💧Hex | plug | all versions | 1.0.6mix deps.update plug |
| 💧Hex | plug | ≥ 1.1.0&&< 1.1.9 | 1.1.9mix deps.update plug |
| 💧Hex | plug | ≥ 1.2.0&&< 1.2.5 | 1.2.5mix deps.update plug |
| 💧Hex | plug | ≥ 1.3.0&&< 1.3.5 | 1.3.5mix deps.update plug |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for plug, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update plug to 1.0.6 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2018-1000883 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-2018-1000883 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2018-1000883. 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-2018-1000883 in your dependencies?
O3 Security finds CVE-2018-1000883 across Hex dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.