CVE-2021-21290

MEDIUMNVD 5.55.5—
EchelonGraph scoreMEDIUM confidence

This medium-severity CVE scores 5.5 under NVD CVSS v3. EPSS exploit probability: 1.8% (77th percentile of EPSS-scored CVEs). GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, nvd
Trending — 4 sources updated this week
5.5EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 1.8%CVSS: 5.5Exploit: None knownExposed services: Not assessed

A fix is available — apply it.

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.

CVSS v3
5.5
EG Score
5.5MEDIUMmedium confidence
EG Risk
25
EG Risk 25/100CISA SSVC

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity55% × 45%
Exploitation2% × 40%
Automatability0% × 15%
CISA SSVC: Track at every mission impact level.
Action: A fix is available. Apply it within your standard update timelines.
EPSS PROB
1.8%
EPSS %ILE
77th
KEV
Not listed

CISA SSVCTrack at every mission impact level.

A fix is available. Apply it within your standard update timelines.

Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). Mission impact is CISA's Mission & Well-being decision point, and only you can judge it: high means the affected system is essential to your organisation's mission, or its compromise could cause irreversible harm to people. CISA's decision table

Published

February 8, 2021

Last Modified

October 8, 2026

Advisory Details (10)

Auto-updated Oct 8, 2026
Patch available. Sources: github, github_commit.
generic

Pony Mail

https://lists.apache.org/thread.html/rdba4f78ac55f803893a1a2265181595e79e3aa027e2e651dfba98c18%40%3Cjira.kafka.apache.org%3E
generic

Pony Mail

https://lists.apache.org/thread.html/r326ec431f06eab7cb7113a7a338e59731b8d556d05258457f12bac1b%40%3Cdev.kafka.apache.org%3E
generic

Pony Mail

https://lists.apache.org/thread.html/r2fda4dab73097051977f2ab818f75e04fbcb15bb1003c8530eac1059%40%3Cjira.kafka.apache.org%3E
generic

Pony Mail

https://lists.apache.org/thread.html/r10308b625e49d4e9491d7e079606ca0df2f0a4d828f1ad1da64ba47b%40%3Cjira.kafka.apache.org%3E
generic

Pony Mail

https://lists.apache.org/thread.html/ra503756ced78fdc2136bd33e87cb7553028645b261b1f5c6186a121e%40%3Cjira.kafka.apache.org%3E
generic

Pony Mail

https://lists.apache.org/thread.html/r2748097ea4b774292539cf3de6e3b267fc7a88d6c8ec40f4e2e87bd4%40%3Cdev.kafka.apache.org%3E
generic

Pony Mail

https://lists.apache.org/thread.html/rc488f80094872ad925f0c73d283d4c00d32def81977438e27a3dc2bb%40%3Cjira.kafka.apache.org%3E
genericMentions a patch (unverified)

[SECURITY] [DLA 2555-1] netty security update

https://lists.debian.org/debian-lts-announce/2021/02/msg00016.html
github_commit Patch Available

commit c735357bf29d (netty/netty)

Patch available: netty/netty netty-4.1.132.Final (contains commit c735357bf29d)

https://github.com/netty/netty/commit/c735357bf29d07856ad171c6611a2e1a0e0000ec
githubMentions a patch (unverified)

Local Information Disclosure Vulnerability in Netty on Unix-Like systems due temporary files · Advisory · netty/netty · GitHub

https://github.com/netty/netty/security/advisories/GHSA-5mcr-gq6c-3hq2

Vendor Advisories for CVE-2021-21290(16)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Patch Availability(9)

Vendor / EcosystemFix (by version range) / PatchReleasedSource
ubuntulibnetty-java (1:4.1.48-5ubuntu0.1) @ kinetic2026-10-08ubuntu
redhatcandlepin-0:4.1.13-1.el8sat2022-07-05redhat
redhatnetty2022-03-29redhat
redhatsatellite-0:6.10.2-1.el7sat2022-01-19redhat
redhatpatch2021-09-30redhat
redhateap7-yasson-0:1.0.9-1.redhat_00001.1.el6eap2021-05-19redhat
redhateap7-yasson-0:1.0.9-1.redhat_00001.1.el7eap2021-05-19redhat
redhateap7-yasson-0:1.0.9-1.redhat_00001.1.el8eap2021-05-19redhat
redhatqpid-proton-0:0.33.0-8.el82021-05-06redhat

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

Affected Packages

(9 across 7 ecosystems)
Maven(3)
PackageVulnerable rangeFix by version rangeDependents
io.netty:netty3.10.0.Final ... 4.0.0.Alpha8 (71 versions)
  • every version on: no fix on record
—
io.netty:netty-codec-http4.0.0.Final ... 4.1.9.Final (132 versions)
  • 4.0.0 up to 4.1.59.Final: fixed in 4.1.59.Final
—
org.jboss.netty:netty3.0.0.CR1 ... 3.2.9.Final (39 versions)
  • every version on: no fix on record
—
Debian:10(1)
PackageVulnerable rangeFix by version rangeDependents
netty1:4.1.33-1, 1:4.1.33-1+deb10u1
  • every version up to 1:4.1.33-1+deb10u2: fixed in 1:4.1.33-1+deb10u2
—
Debian:11(1)
PackageVulnerable rangeFix by version rangeDependents
netty—
  • every version up to 1:4.1.48-2: fixed in 1:4.1.48-2
—
Debian:12(1)
PackageVulnerable rangeFix by version rangeDependents
netty—
  • every version up to 1:4.1.48-2: fixed in 1:4.1.48-2
—
Debian:13(1)
PackageVulnerable rangeFix by version rangeDependents
netty—
  • every version up to 1:4.1.48-2: fixed in 1:4.1.48-2
—
Debian:14(1)
PackageVulnerable rangeFix by version rangeDependents
netty—
  • every version up to 1:4.1.48-2: fixed in 1:4.1.48-2
—
Debian:9(1)
PackageVulnerable rangeFix by version rangeDependents
netty1:4.1.7-2, 1:4.1.7-2+deb9u1, 1:4.1.7-2+deb9u2
  • every version up to 1:4.1.7-2+deb9u3: fixed in 1:4.1.7-2+deb9u3
—

Weakness Classification(3)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Additional Vendor Advisories

(5)

Vendors that published advisories for this CVE beyond the curated set above. Broader coverage but minimal per-row detail — click through for the original advisory.

Data Freshness Timeline

(refreshed 12× in last 7d / 35× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

Showing the most recent 100 of 187 total refreshes for this CVE.

  1. 2026-10-09 20:04 UTCEPSS rescore
  2. 2026-10-08 22:28 UTCEG score recompute▼ 0.70
  3. 2026-10-08 22:28 UTCVendor advisory
  4. 2026-10-08 22:19 UTCNVD updateCVSS v3 → 5.5
  5. 2026-10-08 21:34 UTCEG score recompute
  6. 2026-10-08 21:34 UTCVendor advisory
  7. 2026-10-08 16:39 UTCEPSS rescore
  8. 2026-10-07 23:44 UTCEPSS rescore
  9. 2026-10-06 15:13 UTCEPSS rescore
  10. 2026-10-05 17:40 UTCEPSS rescore
  11. 2026-10-03 14:22 UTCEPSS rescore
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  14. 2026-10-01 19:46 UTCEPSS rescore
  15. 2026-09-30 15:29 UTCEG score recompute
  16. 2026-09-30 15:00 UTCEPSS rescore
  17. 2026-09-28 13:47 UTCEPSS rescore
  18. 2026-09-27 13:41 UTCEPSS rescore
  19. 2026-09-26 15:54 UTCEPSS rescore
  20. 2026-09-26 15:54 UTCEPSS rescore
  21. 2026-09-26 11:25 UTCOSV refresh
  22. 2026-09-26 00:21 UTCEPSS rescore
  23. 2026-09-24 14:00 UTCEPSS rescore
  24. 2026-09-24 14:00 UTCEPSS rescore
  25. 2026-09-23 13:44 UTCEPSS rescore
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  1. 2026-09-22 14:44 UTCEPSS rescore
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  3. 2026-09-19 15:37 UTCEPSS rescore
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  5. 2026-09-17 19:23 UTCEPSS rescore
  6. 2026-09-16 14:05 UTCEPSS rescore
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  8. 2026-09-15 03:06 UTCEPSS rescore
  9. 2026-09-12 14:57 UTCEPSS rescore
  10. 2026-09-11 09:33 UTCEPSS rescore
  11. 2026-09-10 09:29 UTCEPSS rescore
  12. 2026-09-08 21:56 UTCEPSS rescore
  13. 2026-09-07 15:58 UTCEPSS rescore
  14. 2026-09-06 23:01 UTCOSV refresh
  15. 2026-09-06 13:44 UTCEPSS rescore
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  17. 2026-09-05 15:25 UTCEPSS rescore
  18. 2026-09-04 13:57 UTCEPSS rescore
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  23. 2026-08-30 19:14 UTCEPSS rescore
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  25. 2026-08-28 21:37 UTCEPSS rescore
  26. 2026-08-27 14:22 UTCEPSS rescore
  27. 2026-08-26 14:42 UTCEPSS rescore
  28. 2026-08-25 13:45 UTCEPSS rescore
  29. 2026-08-23 00:16 UTCEPSS rescore
  30. 2026-08-21 23:46 UTCEPSS rescore
  31. 2026-08-20 22:52 UTCEPSS rescore
  32. 2026-08-20 09:01 UTCOSV refresh
  33. 2026-08-19 17:01 UTCEPSS rescore
  34. 2026-08-18 13:45 UTCEPSS rescore
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  36. 2026-08-16 14:52 UTCEPSS rescore
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  38. 2026-08-15 01:27 UTCEPSS rescore
  39. 2026-08-13 21:57 UTCEPSS rescore
  40. 2026-08-12 13:47 UTCEPSS rescore
  41. 2026-08-11 13:38 UTCEPSS rescore
  42. 2026-08-09 13:43 UTCEPSS rescore
  43. 2026-08-08 16:33 UTCEPSS rescore
  44. 2026-08-07 16:23 UTCEPSS rescore
  45. 2026-08-06 13:43 UTCEPSS rescore
  46. 2026-08-05 19:14 UTCEPSS rescore
  47. 2026-08-05 04:40 UTCOSV refresh
  48. 2026-08-04 15:06 UTCEPSS rescore
  49. 2026-08-04 10:34 UTCEPSS rescore
  50. 2026-08-03 10:32 UTCEPSS rescore
  51. 2026-08-02 02:24 UTCEPSS rescore
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  56. 2026-07-26 14:52 UTCEPSS rescore
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  58. 2026-07-24 14:15 UTCEPSS rescore
  59. 2026-07-23 14:15 UTCEPSS rescore
  60. 2026-07-23 01:57 UTCEG score recompute
  61. 2026-07-22 22:43 UTCEG score recompute
  62. 2026-07-22 14:05 UTCEPSS rescore
  63. 2026-07-21 15:22 UTCEPSS rescore
  64. 2026-07-21 15:22 UTCEPSS rescore
  65. 2026-07-20 17:04 UTCEPSS rescore
  66. 2026-07-19 14:28 UTCEPSS rescore
  67. 2026-07-19 02:52 UTCOSV refresh
  68. 2026-07-19 02:26 UTCEPSS rescore
  69. 2026-07-18 10:02 UTCEPSS rescore
  70. 2026-07-16 17:00 UTCEPSS rescore
  71. 2026-07-15 16:55 UTCEPSS rescore
  72. 2026-07-15 16:55 UTCEPSS rescore
  73. 2026-07-15 01:57 UTCEPSS rescore
  74. 2026-07-13 22:27 UTCEPSS rescore
  75. 2026-07-13 22:27 UTCEPSS rescore

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Frequently asked(5)

What is CVE-2021-21290?
CVE-2021-21290 is a medium vulnerability published on February 8, 2021. 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…
When was CVE-2021-21290 disclosed?
CVE-2021-21290 was first published on February 8, 2021, with the most recent update on October 8, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2021-21290 actively exploited?
CVE-2021-21290 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 1.8% probability of exploitation in the next 30 days (77th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2021-21290?
CVE-2021-21290 has a CVSS v3 base score of 5.5 (NVD).
How do I remediate CVE-2021-21290?
A fix for CVE-2021-21290 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2021-21290 are linked in the Vendor Advisories panel on this page.

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