CVE-2021-21290 | Local Information Disclosure Vulnerability in Netty on Unix-Like systems due temporary files

Exp

Netty is an open-source, asynchronous event-driven network application framework for rapid development of maintainable high performance protocol servers & clients. In Netty before version 4.1.59.Final there is a vulnerability on Unix-like systems involving an insecure temp file. When netty's multipart decoders are used local information disclosure can occur via the local system temporary directory if temporary storing uploads on the disk is enabled. On unix-like systems, the temporary directory is shared between all user. As such, writing to this directory using APIs that do not explicitly set the file/directory permissions can lead to information disclosure. Of note, this does not impact modern MacOS Operating Systems. The method "File.createTempFile" on unix-like systems creates a random file, but, by default will create this file with the permissions "-rw-r--r--". Thus, if sensitive information is written to this file, other local users can read this information. This is the case in netty's "AbstractDiskHttpData" is vulnerable. This has been fixed in version 4.1.59.Final. As a workaround, one may specify your own "java.io.tmpdir" when you start the JVM or use "DefaultHttpDataFactory.setBaseDir(...)" to set the directory to something that is only readable by the current user.

Published: 2021-02-08 Last update: 2024-11-21 Assigner: [email protected] Source: [email protected]

Conclusion & alert: CVE-2021-21290 is rated High Exploit Risk (67.9/100): CVSS Medium severity, with medium exploitation likelihood (EPSS 1.78%). Core evidence: 1 public exploit reference(s) are indexed (Exploit-DB). EPSS rose +1.75% over the last day, indicating growing attacker interest. Mandatory action: Public exploits are available—assess exposure, apply mitigations, and prioritize patching.

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

Public exploit references (Exploit-DB) for CVE-2021-21290

EDB-ID Source Kind Published Link
nvd_ref exploit_tag Exploit-DB ↗

Exploit prediction scoring system (EPSS) score for CVE-2021-21290

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 2026-06-15 0.02% 1.78% +1.75%
2 2025-11-21 0.07% 0.02% -0.05%
3 2025-11-18 0.07%

Full EPSS history (15 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2021-21290

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
6.2 3.1 MEDIUM
CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N Click to expand
Attack vector (AV:L)
They already need access on the box, or another person has to do something wrong; it’s not a remote drive-by.
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:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:N)
Service keeps running; no real outage angle.
2.5 3.6 [email protected]
5.5 3.1 MEDIUM
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N Click to expand
Attack vector (AV:L)
They already need access on the box, or another person has to do something wrong; it’s not a remote drive-by.
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:L)
A normal user session is enough; they don’t have to be admin.
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:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:N)
Service keeps running; no real outage angle.
1.8 3.6 [email protected]
1.9 2.0 LOW
AV:L/AC:M/Au:N/C:P/I:N/A:N Click to expand
Access vector (AV:L)
Requires local access to the target system.
Access complexity (AC:M)
Exploitation needs some favorable conditions, but not exceptional ones.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:P)
Partial confidentiality impact.
Integrity impact (I:N)
No integrity impact.
Availability impact (A:N)
No availability impact.
3.4 2.9 [email protected]

Weakness enumeration for CVE-2021-21290

GitHub Security Advisory for CVE-2021-21290

GHSA-5mcr-gq6c-3hq2 · Severity: medium · Ecosystem: maven — Local Information Disclosure Vulnerability in Netty on Unix-Like systems

OS Trackers for CVE-2021-21290

vendor priority summary link
debian not yet assigned CVE-2021-21290 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-2021-21290
redhat medium https://access.redhat.com/security/cve/CVE-2021-21290
suse medium CVE-2021-21290 severity moderate: SUSE including 242 source package names (5.0.0-beta1.2.122:netty-4.1.75-150200.4.6.2, 5.1.0.6.40:netty-4.1.75-150200.4.6.2, …), 262 product×package rows across 28 product lines (Container suse/manager/5.0/x86_64/server, Container suse/multi-linux-manager/5.1/x86_64/server, … (28 product lines)): Known Affected 231, Fixed 31. https://www.suse.com/security/cve/CVE-2021-21290/
ubuntu medium CVE-2021-21290 medium priority: Ubuntu including 1 source packages (netty), 16 status rows across 16 suites (bionic, focal, groovy, hirsute, impish, jammy, kinetic, lunar, mantic, noble, oracular, plucky, questing, trusty, upstream, xenial): released 11, ignored 4, needs-triage 1. https://ubuntu.com/security/CVE-2021-21290

Affected software / configurations for CVE-2021-21290

Vendor Product Version Raw CPE
netty netty < 4.1.59 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:*:*:*:*:*:*:*
quarkus quarkus <= 1.13.7 cpe:2.3:a:quarkus:quarkus:*:*:*:*:*:*:*:*
oracle banking_corporate_lending_process_management 14.2.0 cpe:2.3:a:oracle:banking_corporate_lending_process_management:14.2.0:*:*:*:*:*:*:*
oracle banking_corporate_lending_process_management 14.3.0 cpe:2.3:a:oracle:banking_corporate_lending_process_management:14.3.0:*:*:*:*:*:*:*
oracle banking_corporate_lending_process_management 14.5.0 cpe:2.3:a:oracle:banking_corporate_lending_process_management:14.5.0:*:*:*:*:*:*:*
oracle banking_credit_facilities_process_management 14.2.0 cpe:2.3:a:oracle:banking_credit_facilities_process_management:14.2.0:*:*:*:*:*:*:*
oracle banking_credit_facilities_process_management 14.3.0 cpe:2.3:a:oracle:banking_credit_facilities_process_management:14.3.0:*:*:*:*:*:*:*
oracle banking_credit_facilities_process_management 14.5.0 cpe:2.3:a:oracle:banking_credit_facilities_process_management:14.5.0:*:*:*:*:*:*:*
oracle banking_trade_finance_process_management 14.2.0 cpe:2.3:a:oracle:banking_trade_finance_process_management:14.2.0:*:*:*:*:*:*:*
oracle banking_trade_finance_process_management 14.3.0 cpe:2.3:a:oracle:banking_trade_finance_process_management:14.3.0:*:*:*:*:*:*:*
oracle banking_trade_finance_process_management 14.5.0 cpe:2.3:a:oracle:banking_trade_finance_process_management:14.5.0:*:*:*:*:*:*:*
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_design_studio 7.4.2 cpe:2.3:a:oracle:communications_design_studio:7.4.2:*:*:*:*:*:*:*
oracle communications_messaging_server 8.1 cpe:2.3:a:oracle:communications_messaging_server:8.1:*:*:*:*:*:*:*
oracle nosql_database < 20.3 cpe:2.3:a:oracle:nosql_database:*:*:*:*:*:*:*:*
netapp active_iq_unified_manager cpe:2.3:a:netapp:active_iq_unified_manager:-:*:*:*:*:linux:*:*
netapp active_iq_unified_manager cpe:2.3:a:netapp:active_iq_unified_manager:-:*:*:*:*:windows:*:*
netapp cloud_secure_agent cpe:2.3:a:netapp:cloud_secure_agent:-:*:*:*:*:*:*:*
netapp snapcenter cpe:2.3:a:netapp:snapcenter:-:*:*:*:*:*:*:*

References for CVE-2021-21290

URL Tags
https://github.com/netty/netty/commit/c735357bf29d07856ad171c6611a2e1a0e0000ec Patch Third Party Advisory
https://github.com/netty/netty/security/advisories/GHSA-5mcr-gq6c-3hq2 Exploit Third Party Advisory
https://lists.apache.org/thread.html/r0053443ce19ff125981559f8c51cf66e3ab4350f47812b8cf0733a05%40%3Cdev.kafka.apache.org%3E
https://lists.apache.org/thread.html/r02e467123d45006a1dda20a38349e9c74c3a4b53e2e07be0939ecb3f%40%3Cdev.ranger.apache.org%3E
https://lists.apache.org/thread.html/r0857b613604c696bf9743f0af047360baaded48b1c75cf6945a083c5%40%3Cjira.kafka.apache.org%3E
https://lists.apache.org/thread.html/r10308b625e49d4e9491d7e079606ca0df2f0a4d828f1ad1da64ba47b%40%3Cjira.kafka.apache.org%3E
https://lists.apache.org/thread.html/r1908a34b9cc7120e5c19968a116ddbcffea5e9deb76c2be4fa461904%40%3Cdev.zookeeper.apache.org%3E
https://lists.apache.org/thread.html/r2748097ea4b774292539cf3de6e3b267fc7a88d6c8ec40f4e2e87bd4%40%3Cdev.kafka.apache.org%3E
https://lists.apache.org/thread.html/r2936730ef0a06e724b96539bc7eacfcd3628987c16b1b99c790e7b87%40%3Cissues.zookeeper.apache.org%3E
https://lists.apache.org/thread.html/r2fda4dab73097051977f2ab818f75e04fbcb15bb1003c8530eac1059%40%3Cjira.kafka.apache.org%3E
https://lists.apache.org/thread.html/r326ec431f06eab7cb7113a7a338e59731b8d556d05258457f12bac1b%40%3Cdev.kafka.apache.org%3E
https://lists.apache.org/thread.html/r4efed2c501681cb2e8d629da16e48d9eac429624fd4c9a8c6b8e7020%40%3Cdev.tinkerpop.apache.org%3E
https://lists.apache.org/thread.html/r584cf871f188c406d8bd447ff4e2fd9817fca862436c064d0951a071%40%3Ccommits.pulsar.apache.org%3E
https://lists.apache.org/thread.html/r59bac5c09f7a4179b9e2460e8f41c278aaf3b9a21cc23678eb893e41%40%3Cjira.kafka.apache.org%3E
https://lists.apache.org/thread.html/r5bf303d7c04da78f276765da08559fdc62420f1df539b277ca31f63b%40%3Cissues.zookeeper.apache.org%3E
https://lists.apache.org/thread.html/r5c701840aa2845191721e39821445e1e8c59711e71942b7796a6ec29%40%3Cusers.activemq.apache.org%3E
https://lists.apache.org/thread.html/r5e4a540089760c8ecc2c411309d74264f1dad634ad93ad583ca16214%40%3Ccommits.kafka.apache.org%3E
https://lists.apache.org/thread.html/r5e66e286afb5506cdfe9bbf68a323e8d09614f6d1ddc806ed0224700%40%3Cjira.kafka.apache.org%3E
https://lists.apache.org/thread.html/r71dbb66747ff537640bb91eb0b2b24edef21ac07728097016f58b01f%40%3Ccommits.kafka.apache.org%3E
https://lists.apache.org/thread.html/r743149dcc8db1de473e6bff0b3ddf10140a7357bc2add75f7d1fbb12%40%3Cdev.zookeeper.apache.org%3E
https://lists.apache.org/thread.html/r790c2926efcd062067eb18fde2486527596d7275381cfaff2f7b3890%40%3Cissues.bookkeeper.apache.org%3E
https://lists.apache.org/thread.html/r7bb3cdc192e9a6f863d3ea05422f09fa1ae2b88d4663e63696ee7ef5%40%3Cdev.ranger.apache.org%3E
https://lists.apache.org/thread.html/r9924ef9357537722b28d04c98a189750b80694a19754e5057c34ca48%40%3Ccommits.pulsar.apache.org%3E
https://lists.apache.org/thread.html/ra0fc2b4553dd7aaf75febb61052b7f1243ac3a180a71c01f29093013%40%3Cjira.kafka.apache.org%3E
https://lists.apache.org/thread.html/ra503756ced78fdc2136bd33e87cb7553028645b261b1f5c6186a121e%40%3Cjira.kafka.apache.org%3E
https://lists.apache.org/thread.html/rb06c1e766aa45ee422e8261a8249b561784186483e8f742ea627bda4%40%3Cdev.kafka.apache.org%3E
https://lists.apache.org/thread.html/rb51d6202ff1a773f96eaa694b7da4ad3f44922c40b3d4e1a19c2f325%40%3Ccommits.pulsar.apache.org%3E
https://lists.apache.org/thread.html/rb592033a2462548d061a83ac9449c5ff66098751748fcd1e2d008233%40%3Cissues.zookeeper.apache.org%3E
https://lists.apache.org/thread.html/rc0087125cb15b4b78e44000f841cd37fefedfda942fd7ddf3ad1b528%40%3Cissues.zookeeper.apache.org%3E
https://lists.apache.org/thread.html/rc488f80094872ad925f0c73d283d4c00d32def81977438e27a3dc2bb%40%3Cjira.kafka.apache.org%3E
https://lists.apache.org/thread.html/rcd163e421273e8dca1c71ea298dce3dd11b41d51c3a812e0394e6a5d%40%3Ccommits.pulsar.apache.org%3E
https://lists.apache.org/thread.html/rdba4f78ac55f803893a1a2265181595e79e3aa027e2e651dfba98c18%40%3Cjira.kafka.apache.org%3E
https://lists.debian.org/debian-lts-announce/2021/02/msg00016.html Mailing List Third Party Advisory
https://security.netapp.com/advisory/ntap-20220210-0011/ Third Party Advisory
https://www.debian.org/security/2021/dsa-4885 Third Party Advisory
https://www.oracle.com//security-alerts/cpujul2021.html Third Party Advisory
https://www.oracle.com/security-alerts/cpuApr2021.html Patch Third Party Advisory
https://www.oracle.com/security-alerts/cpuapr2022.html Patch Third Party Advisory
https://www.oracle.com/security-alerts/cpuoct2021.html Patch Third Party Advisory
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