CVE-2021-35565Network attack vector

Service interruption via looping TLS session close

Published Oct 20, 2021 · Updated Sep 25, 2024

Denial of service in Oracle Java SE 7u311, 8u301, and 11.0.12 allows remote attackers to hang HttpsServer via a TLS connection. HttpsServer enters a loop when a peer closes a TLS session, consuming processing capacity instead of completing connection teardown. Exposure requires an application to supply network data to the JSSE-backed HttpsServer API; the documented consequence is partial service interruption.

CVSS severity5.3
Medium
EPSS probability7.40%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in Oracle Java SE 7u311, 8u301, and 11.0.12 allows remote attackers to hang HttpsServer via a TLS connection. HttpsServer enters a loop when a peer closes a TLS session, consuming processing capacity instead of completing connection teardown. Exposure requires an application to supply network data to the JSSE-backed HttpsServer API; the documented consequence is partial service interruption.

The record

CVE
CVE-2021-35565
Published
Oct 20, 2021
Updated
Sep 25, 2024
Vendor
Oracle Corporation
Product
Java Platform, Standard Edition (Java SE)
Classifications
T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Oct 20, 2021CVE publishedPublication date reported by the CVE source.
  2. Sep 25, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=Java SE:11.0.12
  2. Affected versionversion=Java SE:7u311
  3. Affected versionversion=Java SE:8u301
  4. Affected versionversion=Oracle GraalVM Enterprise Edition:20.3.3
  5. Affected versionversion=Oracle GraalVM Enterprise Edition:21.2.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Oracle Corporation · Java Platform, Standard Edition (Java SE)version=Java SE:11.0.12; version=Java SE:7u311; version=Java SE:8u301; version=Oracle GraalVM Enterprise Edition:20.3.3; version=Oracle GraalVM Enterprise Edition:21.2.0

Published CVSS scores

5.3Oracle CorporationCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1499.004Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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