CVE-2023-4639 — undertow
HIGHCVE-2023-4639 is a high-severity (CVSS 7.4) vulnerability in undertow. A fix is available for undertow — see the affected versions and patch details below.
Undertow incorrectly parses cookies
Real-World Exposure
undertowReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Debian:13 packages — download data is not available via public APIs for these ecosystems.
Description
A flaw was found in Undertow, which incorrectly parses cookies with certain value-delimiting characters in incoming requests. This issue could allow an attacker to construct a cookie value to exfiltrate HttpOnly cookie values or spoof arbitrary additional cookie values, leading to unauthorized data access or modification. The main threat from this flaw impacts data confidentiality and integrity.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦Debian:13 | undertow | all versions | 2.3.18-1 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for undertow, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update undertow to 2.3.18-1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2023-4639 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-2023-4639 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2023-4639. 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-2023-4639 in your dependencies?
O3 Security finds CVE-2023-4639 across Debian:13 dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.