Netty vulnerable to HTTP Response splitting from assigning header value iteratorGHSA-hh82-3pmq-7frp
MEDIUMFix: netty/netty#12760GHSA-hh82-3pmq-7frp is a medium-severity (CVSS 6.5) CWE-113 vulnerability in io.netty:netty-codec-http. 1 public exploit or proof-of-concept reference is indexed, so weaponization risk is real. A fix is available for io.netty:netty-codec-http — see the affected versions and patch details below.
Exploitation Status
Proof-of-concept exploit code exists
- CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
Exploitation and automatability from CISA’s SSVC triage for GHSA-hh82-3pmq-7frp.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
Where this sits among everything scored
Real-World Exposure
io.netty:netty-codec-httpReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Maven packages — download data is not available via public APIs for these ecosystems.
Description
Impact
When calling DefaultHttpHeaders.set with an iterator of values (as opposed to a single given value), header value validation was not performed, allowing malicious header values in the iterator to perform HTTP Response Splitting.
Patches
The necessary validation was added in Netty 4.1.86.Final.
Workarounds
Integrators can work around the issue by changing the DefaultHttpHeaders.set(CharSequence, Iterator<?>) call, into a remove() call, and call add() in a loop over the iterator of values.
References
HTTP Response Splitting CWE-113: Improper Neutralization of CRLF Sequences in HTTP Headers
For more information
If you have any questions or comments about this advisory:
- Open an issue in [example link to repo](https://github.com/netty/netty)
- Email us at [email protected]
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| ☕Maven | io.netty:netty-codec-http | ≥ 4.1.83.Final&&< 4.1.86.Final | 4.1.86.Finalio.netty:netty-codec-http:4.1.86.Final |
Affected Products
debian linuxdebiannettynettyResearch use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for io.netty:netty-codec-http, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update io.netty:netty-codec-http to 4.1.86.Final or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-hh82-3pmq-7frp 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.
Frequently Asked Questions
Is GHSA-hh82-3pmq-7frp in your dependencies?
Find it across Maven, including transitive dependencies.