CVE-2020-11612

The ZlibDecoders in Netty 4.1.x before 4.1.46 allow for unbounded memory allocation while decoding a ZlibEncoded byte stream. An attacker could send a large ZlibEncoded byte stream to the Netty server, forcing the server to allocate all of its free memory to a single decoder.

Published: 2020-04-07 Last update: 2024-11-21 Assigner: [email protected] Source: [email protected]

Conclusion & alert: CVE-2020-11612 is rated Moderate Risk (63.3/100): CVSS High severity, with medium exploitation likelihood (EPSS 4.33%). Core evidence: EPSS rose +2.28% over the last day, indicating growing attacker interest. Mandatory action: Review affected assets and schedule remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2020-11612

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-03-04 2.05% 4.33% +2.28%
2 2026-03-01 4.33% 2.05% -2.28%
3 2026-02-04 4.33%

Full EPSS history (29 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2020-11612

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
7.5 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
3.9 3.6 [email protected]
5.0 2.0 MEDIUM
AV:N/AC:L/Au:N/C:N/I:N/A:P Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:L)
Exploitation conditions are straightforward and predictable.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:N)
No confidentiality impact.
Integrity impact (I:N)
No integrity impact.
Availability impact (A:P)
Partial availability impact.
10.0 2.9 [email protected]

Weakness enumeration for CVE-2020-11612

GitHub Security Advisory for CVE-2020-11612

OS Trackers for CVE-2020-11612

vendor priority summary link
debian not yet assigned CVE-2020-11612 not yet assigned priority: Debian including 1 source packages (netty), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. https://security-tracker.debian.org/tracker/CVE-2020-11612
redhat medium https://access.redhat.com/security/cve/CVE-2020-11612
suse medium https://www.suse.com/security/cve/CVE-2020-11612/
ubuntu medium CVE-2020-11612 medium priority: Ubuntu including 1 source packages (netty), 17 status rows across 17 suites (bionic, eoan, focal, groovy, hirsute, impish, jammy, kinetic, lunar, mantic, noble, oracular, plucky, questing, trusty, upstream, xenial): not-affected 11, released 4, ignored 1, needs-triage 1. https://ubuntu.com/security/CVE-2020-11612

Affected software / configurations for CVE-2020-11612

Vendor Product Version Raw CPE
netty netty >= 4.1, < 4.1.46 cpe:2.3:a:netty:netty:*:*:*:*:*:*:*:*
debian debian_linux 9.0 cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*
debian debian_linux 10.0 cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:*
fedoraproject fedora 33 cpe:2.3:o:fedoraproject:fedora:33:*:*:*:*:*:*:*
netapp oncommand_api_services cpe:2.3:a:netapp:oncommand_api_services:-:*:*:*:*:*:*:*
netapp oncommand_insight cpe:2.3:a:netapp:oncommand_insight:-:*:*:*:*:*:*:*
netapp oncommand_workflow_automation cpe:2.3:a:netapp:oncommand_workflow_automation:-:*:*:*:*:*:*:*
oracle communications_brm_-_elastic_charging_engine 12.0.0.3 cpe:2.3:a:oracle:communications_brm_-_elastic_charging_engine:12.0.0.3:*:*:*:*:*:*:*
oracle communications_cloud_native_core_service_communication_proxy 1.5.2 cpe:2.3:a:oracle:communications_cloud_native_core_service_communication_proxy:1.5.2:*:*:*:*:*:*:*
oracle communications_design_studio 7.4.2 cpe:2.3:a:oracle:communications_design_studio:7.4.2:*:*:*:*:*:*:*
oracle nosql_database < 20.3 cpe:2.3:a:oracle:nosql_database:*:*:*:*:*:*:*:*
oracle siebel_core_-_server_framework < 21.5 cpe:2.3:a:oracle:siebel_core_-_server_framework:*:*:*:*:*:*:*:*
oracle webcenter_portal 12.2.1.3.0 cpe:2.3:a:oracle:webcenter_portal:12.2.1.3.0:*:*:*:*:*:*:*
oracle webcenter_portal 12.2.1.4.0 cpe:2.3:a:oracle:webcenter_portal:12.2.1.4.0:*:*:*:*:*:*:*
oracle communications_messaging_server 8.1 cpe:2.3:o:oracle:communications_messaging_server:8.1:*:*:*:*:*:*:*

References for CVE-2020-11612

URL Tags
https://github.com/netty/netty/compare/netty-4.1.45.Final...netty-4.1.46.Final Patch Third Party Advisory
https://github.com/netty/netty/issues/6168 Third Party Advisory
https://github.com/netty/netty/pull/9924 Patch Third Party Advisory
https://lists.apache.org/thread.html/r14446ed58208cb6d97b6faa6ebf145f1cf2c70c0886c0c133f4d3b6f%40%3Ccommits.druid.apache.org%3E
https://lists.apache.org/thread.html/r255ed239e65d0596812362adc474bee96caf7ba042c7ad2f3c62cec7%40%3Cissues.zookeeper.apache.org%3E
https://lists.apache.org/thread.html/r281882fdf9ea89aac02fd2f92786693a956aac2ce9840cce87c7df6b%40%3Ccommits.zookeeper.apache.org%3E
https://lists.apache.org/thread.html/r2958e4d49ee046e1e561e44fdc114a0d2285927501880f15852a9b53%40%3Ccommits.druid.apache.org%3E
https://lists.apache.org/thread.html/r31424427cc6d7db46beac481bdeed9a823fc20bb1b9deede38557f71%40%3Cnotifications.zookeeper.apache.org%3E
https://lists.apache.org/thread.html/r3195127e46c87a680b5d1d3733470f83b886bfd3b890c50df718bed1%40%3Ccommits.druid.apache.org%3E
https://lists.apache.org/thread.html/r3ea4918d20d0c1fa26cac74cc7cda001d8990bc43473d062867ef70d%40%3Cnotifications.zookeeper.apache.org%3E
https://lists.apache.org/thread.html/r4a7e4e23bd84ac24abf30ab5d5edf989c02b555e1eca6a2f28636692%40%3Cnotifications.zookeeper.apache.org%3E
https://lists.apache.org/thread.html/r4f4a14d6a608db447b725ec2e96c26ac9664d83cd879aa21e2cfeb24%40%3Cnotifications.zookeeper.apache.org%3E
https://lists.apache.org/thread.html/r5030cd8ea5df1e64cf6a7b633eff145992fbca03e8bfc687cd2427ab%40%3Cnotifications.zookeeper.apache.org%3E
https://lists.apache.org/thread.html/r5a0b1f0b1c3bcd66f5177fbd6f6de2d0f8cae24a13ab2669f274251a%40%3Cnotifications.zookeeper.apache.org%3E
https://lists.apache.org/thread.html/r5b1ad61552591b747cd31b3a908d5ff2e8f2a8a6847583dd6b7b1ee7%40%3Cissues.zookeeper.apache.org%3E
https://lists.apache.org/thread.html/r69b23a94d4ae45394cabae012dd1f4a963996869c44c478eb1c61082%40%3Ccommits.zookeeper.apache.org%3E
https://lists.apache.org/thread.html/r7641ee788e1eb1be4bb206a7d15f8a64ec6ef23e5ec6132d5a567695%40%3Cnotifications.zookeeper.apache.org%3E
https://lists.apache.org/thread.html/r7790b9d99696d9eddce8a8c96f13bb68460984294ea6fea3800143e4%40%3Ccommits.pulsar.apache.org%3E
https://lists.apache.org/thread.html/r7836bbdbe95c99d4d725199f0c169927d4e87ba57e4beeeb699c097a%40%3Ccommits.druid.apache.org%3E
https://lists.apache.org/thread.html/r832724df393a7ef25ca4c7c2eb83ad2d6c21c74569acda5233f9f1ec%40%3Ccommits.pulsar.apache.org%3E
https://lists.apache.org/thread.html/r866288c2ada00ce148b7307cdf869f15f24302b3eb2128af33830997%40%3Ccommits.zookeeper.apache.org%3E
https://lists.apache.org/thread.html/r88e2b91560c065ed67e62adf8f401c417e4d70256d11ea447215a70c%40%3Cissues.zookeeper.apache.org%3E
https://lists.apache.org/thread.html/r8a654f11e1172b0effbfd6f8d5b6ca651ae4ac724a976923c268a42f%40%3Ccommits.druid.apache.org%3E
https://lists.apache.org/thread.html/r9addb580456807cd11d6f0c6b6373b7d7161d06d2278866c30c7febb%40%3Ccommits.zookeeper.apache.org%3E
https://lists.apache.org/thread.html/r9c30b7fca4baedebcb46d6e0f90071b30cc4a0e074164d50122ec5ec%40%3Ccommits.zookeeper.apache.org%3E
https://lists.apache.org/thread.html/ra98e3a8541a09271f96478d5e22c7e3bd1afdf48641c8be25d62d9f9%40%3Ccommits.druid.apache.org%3E
https://lists.apache.org/thread.html/raaac04b7567c554786132144bea3dcb72568edd410c1e6f0101742e7%40%3Cissues.flink.apache.org%3E
https://lists.apache.org/thread.html/rd302ddb501fa02c5119120e5fc21df9a1c00e221c490edbe2d7ad365%40%3Cnotifications.zookeeper.apache.org%3E
https://lists.apache.org/thread.html/rdb69125652311d0c41f6066ff44072a3642cf33a4b5e3c4f9c1ec9c2%40%3Ccommits.pulsar.apache.org%3E
https://lists.apache.org/thread.html/re1ea144e91f03175d661b2d3e97c7d74b912e019613fa90419cf63f4%40%3Cissues.zookeeper.apache.org%3E
https://lists.apache.org/thread.html/ref2c8a0cbb3b8271e5b9a06457ba78ad2028128627186531730f50ef%40%3Cnotifications.zookeeper.apache.org%3E
https://lists.apache.org/thread.html/ref3943adbc3a8813aee0e3a9dd919bacbb27f626be030a3c6d6c7f83%40%3Ccommits.pulsar.apache.org%3E
https://lists.apache.org/thread.html/rf5b2dfb7401666a19915f8eaef3ba9f5c3386e2066fcd2ae66e16a2f%40%3Cdev.flink.apache.org%3E
https://lists.apache.org/thread.html/rf803b65b4a57589d79cf2e83d8ece0539018d32864f932f63c972844%40%3Cnotifications.zookeeper.apache.org%3E
https://lists.apache.org/thread.html/rf9f8bcc4ca8d2788f77455ff594468404732a4497baebe319043f4d5%40%3Ccommits.zookeeper.apache.org%3E
https://lists.apache.org/thread.html/rfd173eac20d5e5f581c8984b685c836dafea8eb2f7ff85f617704cf1%40%3Cdev.zookeeper.apache.org%3E
https://lists.apache.org/thread.html/rff8859c0d06b1688344b39097f9685c43b461cf2bc41f60f001704e9%40%3Ccommits.zookeeper.apache.org%3E
https://lists.debian.org/debian-lts-announce/2020/09/msg00003.html Mailing List Third Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/TS6VX7OMXPDJIU5LRGUAHRK6MENAVJ46/
https://security.netapp.com/advisory/ntap-20201223-0001/ Third Party Advisory
https://www.debian.org/security/2021/dsa-4885 Third Party Advisory
https://www.oracle.com//security-alerts/cpujul2021.html Patch Third Party Advisory
https://www.oracle.com/security-alerts/cpuApr2021.html Patch Third Party Advisory
https://www.oracle.com/security-alerts/cpuapr2022.html Third Party Advisory
https://www.oracle.com/security-alerts/cpujan2021.html Patch Third Party Advisory
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