CVE-2019-20444: HttpObjectDecoder.java in Netty before 4.1.44 allows an HTTP header that lacks a colon, which might be interpreted as a separate header with…
Noroxi assessment
Priority: Monitor (action score 39/100)
- The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
- Probability of exploitation in the next 30 days: 8.9% (FIRST EPSS); higher than 95.3% of all records.
- Anyone who can reach it over the internet can trigger it. No account or password is required. No user action is required. No special conditions are required; it is repeatable.
- According to CISA the attack is automatable: targets can be found by mass scanning.
- Fixed version: netty (Debian:10) 1:4.1.33-1+deb10u2; netty (Debian:12) 1:4.1.45-1; netty (Debian:8) 1:3.2.6.Final-2+deb8u2.
Low priority for now. Upgrade to netty (Debian:10) 1:4.1.33-1+deb10u2; netty (Debian:12) 1:4.1.45-1; netty (Debian:8) 1:3.2.6.Final-2+deb8u2 or later.
Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it
Primary sources: NVD · CVE.org · FIRST EPSS
HttpObjectDecoder.java in Netty before 4.1.44 allows an HTTP header that lacks a colon, which might be interpreted as a separate header with an incorrect syntax, or might be interpreted as an "invalid fold."
- Published
- Jan 29, 2020
- Updated
- Oct 8, 2026
- EPSS
- 8.9% · 95th percentile
- CWE
- CWE-444
Report tools
Action score
39
Low priority for now.
- CVSS
- 36 / 40 · 9.1 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 3 / 30 · 8.9%
CISA SSVC decision
- Exploitation
- none
- Automatable
- yes
- Technical impact
- total
Vulnrichment: CISA's decision-tree inputs.
Get told when this record changes
- Not in KEV: no record of exploitation in the wild
- No public exploit code on record
- A fix has been released
If any of these changes, we'll tell you in the daily email digest.
Is your version affected? Check itNoroxi analysis
What does it mean in your environment?
The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.
We use this product, ask for helpAffected systems
Is your version affected?
Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.
| Vendor | Product | CPE |
|---|---|---|
| netty | netty | cpe:2.3:a:netty:netty |
| debian | debian linux | cpe:2.3:o:debian:debian_linux |
| fedoraproject | fedora | cpe:2.3:o:fedoraproject:fedora |
| canonical | ubuntu linux | cpe:2.3:o:canonical:ubuntu_linux |
| redhat | jboss amq clients | cpe:2.3:a:redhat:jboss_amq_clients |
| redhat | jboss enterprise application platform | cpe:2.3:a:redhat:jboss_enterprise_application_platform |
| redhat | enterprise linux | cpe:2.3:o:redhat:enterprise_linux |
Affected versions
NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.
- canonical ubuntu linux18.04
- debian debian linux10.0
- debian debian linux8.0
- debian debian linux9.0
- fedoraproject fedora33
- netty nettybefore 4.1.44
- redhat jboss amq clients2
- redhat jboss enterprise application platform7.2
- redhat jboss enterprise application platform7.3
Package-level exposure
OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.
| Ecosystem | Package | Affected range | Fix |
|---|---|---|---|
| Debian:10 | netty | before 1:4.1.33-1+deb10u2 | 1:4.1.33-1+deb10u2 |
| Debian:12 | netty | before 1:4.1.45-1 | 1:4.1.45-1 |
| Debian:8 | netty | before 1:3.2.6.Final-2+deb8u2 | 1:3.2.6.Final-2+deb8u2 |
| Debian:8 | netty-3.9 | before 3.9.0.Final-1+deb8u1 | 3.9.0.Final-1+deb8u1 |
| Debian:9 | netty | before 1:4.1.7-2+deb9u2 | 1:4.1.7-2+deb9u2 |
| Debian:9 | netty-3.9 | before 3.9.9.Final-1+deb9u1 | 3.9.9.Final-1+deb9u1 |
| Maven | io.netty:netty | from 0 | — |
| Maven | io.netty:netty-codec-http | before 4.1.44 | 4.1.44 |
| Maven | org.jboss.netty:netty | from 0 | — |
| Red Hat:a_mq_clients:2::el6 | python-qpid-proton | before 0:0.30.0-4.el6_10 | 0:0.30.0-4.el6_10 |
| Red Hat:a_mq_clients:2::el6 | python-qpid-proton-docs | before 0:0.30.0-4.el6_10 | 0:0.30.0-4.el6_10 |
| Red Hat:a_mq_clients:2::el6 | qpid-proton | before 0:0.30.0-4.el6_10 | 0:0.30.0-4.el6_10 |
| Red Hat:a_mq_clients:2::el6 | qpid-proton-c | before 0:0.30.0-4.el6_10 | 0:0.30.0-4.el6_10 |
| Red Hat:a_mq_clients:2::el6 | qpid-proton-c-devel | before 0:0.30.0-4.el6_10 | 0:0.30.0-4.el6_10 |
| Red Hat:a_mq_clients:2::el6 | qpid-proton-c-docs | before 0:0.30.0-4.el6_10 | 0:0.30.0-4.el6_10 |
| Red Hat:a_mq_clients:2::el6 | qpid-proton-cpp | before 0:0.30.0-4.el6_10 | 0:0.30.0-4.el6_10 |
| Red Hat:a_mq_clients:2::el6 | qpid-proton-cpp-devel | before 0:0.30.0-4.el6_10 | 0:0.30.0-4.el6_10 |
| Red Hat:a_mq_clients:2::el6 | qpid-proton-cpp-docs | before 0:0.30.0-4.el6_10 | 0:0.30.0-4.el6_10 |
| Red Hat:a_mq_clients:2::el6 | qpid-proton-debuginfo | before 0:0.30.0-4.el6_10 | 0:0.30.0-4.el6_10 |
| Red Hat:a_mq_clients:2::el6 | qpid-proton-tests | before 0:0.30.0-4.el6_10 | 0:0.30.0-4.el6_10 |
| Red Hat:a_mq_clients:2::el7 | python-qpid-proton | before 0:0.30.0-2.el7 | 0:0.30.0-2.el7 |
| Red Hat:a_mq_clients:2::el7 | python-qpid-proton-docs | before 0:0.30.0-2.el7 | 0:0.30.0-2.el7 |
| Red Hat:a_mq_clients:2::el7 | qpid-proton | before 0:0.30.0-2.el7 | 0:0.30.0-2.el7 |
| Red Hat:a_mq_clients:2::el7 | qpid-proton-c | before 0:0.30.0-2.el7 | 0:0.30.0-2.el7 |
+96
Same product
netty: all recordsOther highest-scoring records for the same primary product.
- CVE-2026-47691Netty has Insufficient Bailiwick Validation for NS Records40Plan
- CVE-2026-45674Netty Vulnerable to DNS Cache Poisoning via Missing Bailiwick Checks in CNAME Records40Plan
- CVE-2019-20445HttpObjectDecoder.java in Netty before 4.1.44 allows a Content-Length header to be accompanied by a second Content-Length header, or by a…40Plan
Published before and after this one in the same product
- ← EarlierCVE-2019-16869Sep 26, 2019 · Netty before 4.1.42.Final mishandles whitespace before the colon in HTTP headers (such as a "Transfer-Encoding : chunked" line), which…33Monitor
- ← EarlierCVE-2020-7238Jan 27, 2020 · Netty 4.1.43.Final allows HTTP Request Smuggling because it mishandles Transfer-Encoding whitespace (such as a…31Monitor
- Later →CVE-2020-11612Apr 7, 2020 · The ZlibDecoders in Netty 4.1.x before 4.1.46 allow for unbounded memory allocation while decoding a ZlibEncoded byte stream.33Monitor
Remediation
Which version to upgrade to
Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.
| Product / package | Fixed version | Source |
|---|---|---|
| debian:netty | 1:4.1.45-1 · Debian:12 | Package registry (OSV) |
| debian:netty-3.9 | 3.9.0.Final-1+deb8u1 · Debian:8 | Package registry (OSV) |
| Maven:io.netty:netty-codec-http | 4.1.44 | Package registry (OSV) |
| red hat:python-qpid-proton | 0:0.30.0-4.el6_10 · Red Hat:a_mq_clients:2::el6 | Package registry (OSV) |
| red hat:python-qpid-proton-docs | 0:0.30.0-4.el6_10 · Red Hat:a_mq_clients:2::el6 | Package registry (OSV) |
| red hat:qpid-proton | 0:0.30.0-4.el6_10 · Red Hat:a_mq_clients:2::el6 | Package registry (OSV) |
| red hat:qpid-proton-c | 0:0.30.0-4.el6_10 · Red Hat:a_mq_clients:2::el6 | Package registry (OSV) |
| red hat:qpid-proton-c-devel | 0:0.30.0-4.el6_10 · Red Hat:a_mq_clients:2::el6 | Package registry (OSV) |
| red hat:qpid-proton-c-docs | 0:0.30.0-4.el6_10 · Red Hat:a_mq_clients:2::el6 | Package registry (OSV) |
| red hat:qpid-proton-cpp | 0:0.30.0-4.el6_10 · Red Hat:a_mq_clients:2::el6 | Package registry (OSV) |
| red hat:qpid-proton-cpp-devel | 0:0.30.0-4.el6_10 · Red Hat:a_mq_clients:2::el6 | Package registry (OSV) |
| red hat:qpid-proton-cpp-docs | 0:0.30.0-4.el6_10 · Red Hat:a_mq_clients:2::el6 | Package registry (OSV) |
| red hat:qpid-proton-debuginfo | 0:0.30.0-4.el6_10 · Red Hat:a_mq_clients:2::el6 | Package registry (OSV) |
| red hat:qpid-proton-tests | 0:0.30.0-4.el6_10 · Red Hat:a_mq_clients:2::el6 | Package registry (OSV) |
| red hat:rubygem-qpid_proton | 0:0.30.0-1.el7 · Red Hat:a_mq_clients:2::el7 | Package registry (OSV) |
Exploit status
No known public exploit
No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.
Research context
For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.
Timeline
From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.
No dated events beyond publication.
Patch and commit links
Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.
Not on record for this CVE: EPSS history · researcher credit · variant or chain candidate · public bounty program.
Technical details
Attack conditions
- Anyone who can reach it over the internet can trigger it.
- No account or password is required.
- No user action is required.
- No special conditions are required; it is repeatable.
If successful
- Confidentiality
- high · data can be read
- Integrity
- high · data or configuration can be modified
- Availability
- none
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality impact
- High
- Integrity impact
- High
- Availability impact
- None
Weakness class (CWE)
CWE-444 · Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
nvd-primary
Attack context
MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.
Attack patterns (CAPEC)
ATT&CK techniques
—
Change log (2)
- SSVC exploitation— → none
- Fix✗ → ✓
For records you follow, these changes also arrive as notifications. →
References
Show all references (19 more)Show less
- access.redhat.com/errata/RHSA-2020:0567
- access.redhat.com/errata/RHSA-2020:0601
- access.redhat.com/errata/RHSA-2020:0605
- access.redhat.com/errata/RHSA-2020:0606
- access.redhat.com/errata/RHSA-2020:0804
- access.redhat.com/errata/RHSA-2020:0805
- access.redhat.com/errata/RHSA-2020:0806
- access.redhat.com/errata/RHSA-2020:0811
- github.com/netty/netty/compare/netty-4.1.43.Final...netty-4.1.44.Final
- github.com/poc-effectiveness/PoCAdaptation/tree/main/Adapted/CVE-2019-20444/5.0.0.Alpha1/exploit
- lists.apache.org/thread.html/r059b042bca47be53ff8a51fd04d95eb01bb683f1afa209db136e8cb7@%3Cdev.zookeeper.apache.org%3E
- lists.apache.org/thread.html/r0aa8b28e76ec01c697b15e161e6797e88fc8d406ed762e253401106e@%3Ccommits.camel.apache.org%3E
- lists.apache.org/thread.html/r0c3d49bfdbc62fd3915676433cc5899c5506d06da1c552ef1b7923a5@%3Ccommon-issues.hadoop.apache.org%3E
- lists.apache.org/thread.html/r0f5e72d5f69b4720dfe64fcbc2da9afae949ed1e9cbffa84bb7d92d7@%3Cnotifications.zookeeper.apache.org%3E
- lists.apache.org/thread.html/r1b103833cb5bc8466e24ff0ecc5e75b45a705334ab6a444e64e840a0@%3Cissues.bookkeeper.apache.org%3E
- lists.apache.org/thread.html/r1fcccf8bdb3531c28bc9aa605a6a1bea7e68cef6fc12e01faafb2fb5@%3Cissues.zookeeper.apache.org%3E
- lists.apache.org/thread.html/r205937c85817a911b0c72655c2377e7a2c9322d6ef6ce1b118d34d8d@%3Cdev.geode.apache.org%3E
- lists.apache.org/thread.html/r2f2989b7815d809ff3fda8ce330f553e5f133505afd04ffbc135f35f@%3Cissues.spark.apache.org%3E
- lists.apache.org/thread.html/r310d2ce22304d5298ff87f10134f918c87919b452734f9841d95682d@%3Ccommits.zookeeper.apache.org%3E
Vendor advisories and official records. Exploit/PoC links are deliberately left out.