CVE-2019-17638

In Eclipse Jetty, versions 9.4.27.v20200227 to 9.4.29.v20200521, in case of too large response headers, Jetty throws an exception to produce an HTTP 431 error. When this happens, the ByteBuffer containing the HTTP response headers is released back to the ByteBufferPool twice. Because of this double release, two threads can acquire the same ByteBuffer from the pool and while thread1 is about to use the ByteBuffer to write response1 data, thread2 fills the ByteBuffer with other data. Thread1 then proceeds to write the buffer that now contains different data. This results in client1, which issued request1 seeing data from another request or response which could contain sensitive data belonging to client2 (HTTP session ids, authentication credentials, etc.). If the Jetty version cannot be upgraded, the vulnerability can be significantly reduced by configuring a responseHeaderSize significantly larger than the requestHeaderSize (12KB responseHeaderSize and 8KB requestHeaderSize).

Published: 2020-07-09 Last update: 2024-11-21 Assigner: [email protected] Source: [email protected]

Conclusion & alert: CVE-2019-17638 is rated High Risk (66/100): CVSS Critical severity, with high exploitation likelihood (EPSS 11.14%, 95th percentile). Core evidence: EPSS ranks this CVE among the most likely to be exploited in the near term. Mandatory action: High exploitation likelihood—assess exposure and prioritize 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-2019-17638

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 30.93% 11.14% -19.79%
2 2026-03-04 25.78% 30.93% +5.15%
3 2026-03-01 25.78%

Full EPSS history (50 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2019-17638

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
9.4 3.1 CRITICAL
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:L 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:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:L)
Might cause slowdowns, glitches, or partial disruption—not a full brick.
3.9 5.5 [email protected]
7.5 2.0 HIGH
AV:N/AC:L/Au:N/C:P/I:P/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:P)
Partial confidentiality impact.
Integrity impact (I:P)
Partial integrity impact.
Availability impact (A:P)
Partial availability impact.
10.0 6.4 [email protected]

Weakness enumeration for CVE-2019-17638

GitHub Security Advisory for CVE-2019-17638

GHSA-x3rh-m7vp-35f2 · Severity: critical · Ecosystem: maven — Operation on a Resource after Expiration or Release in Jetty Server

OS Trackers for CVE-2019-17638

vendor priority summary link
debian not yet assigned CVE-2019-17638 not yet assigned priority: Debian including 1 source packages (jetty9), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. https://security-tracker.debian.org/tracker/CVE-2019-17638
redhat high https://access.redhat.com/security/cve/CVE-2019-17638
ubuntu medium CVE-2019-17638 medium priority: Ubuntu including 1 source packages (jetty9), 16 status rows across 16 suites (bionic, eoan, focal, groovy, hirsute, impish, jammy, kinetic, lunar, mantic, noble, oracular, plucky, trusty, upstream, xenial): ignored 7, not-affected 7, DNE 1, released 1. https://ubuntu.com/security/CVE-2019-17638

Affected software / configurations for CVE-2019-17638

Vendor Product Version Raw CPE
eclipse jetty 9.4.27 cpe:2.3:a:eclipse:jetty:9.4.27:20200227:*:*:*:*:*:*
eclipse jetty 9.4.28 cpe:2.3:a:eclipse:jetty:9.4.28:20200408:*:*:*:*:*:*
eclipse jetty 9.4.29 cpe:2.3:a:eclipse:jetty:9.4.29:20200521:*:*:*:*:*:*

References for CVE-2019-17638

URL Tags
http://www.openwall.com/lists/oss-security/2020/08/17/1
https://bugs.eclipse.org/bugs/show_bug.cgi?id=564984 Vendor Advisory
https://lists.apache.org/thread.html/r29073905dc9139d0d7a146595694bf57bb9e35e5ec6aa73eb9c8443a%40%3Ccommits.pulsar.apache.org%3E
https://lists.apache.org/thread.html/r378e4cdec15e132575aa1dcb6296ffeff2a896745a8991522e266ad4%40%3Ccommits.pulsar.apache.org%3E
https://lists.apache.org/thread.html/r4bdd3f7bb6820a79f9416b6667d718a06d269018619a75ce4b759318%40%3Ccommits.pulsar.apache.org%3E
https://lists.apache.org/thread.html/r521168299e023fb075b57afe33d17ff1d09e8a10e0fd8c775ea0e028%40%3Ccommits.pulsar.apache.org%3E
https://lists.apache.org/thread.html/r7fc5f2ed49641ea91c433e3cd0fc3d31c0278c87b82b15c33b881415%40%3Ccommits.pulsar.apache.org%3E
https://lists.apache.org/thread.html/r81f58591fb4716fb867b36956f30c7c8ad4ab3f23abc952d9d86a2a0%40%3Ccommits.pulsar.apache.org%3E
https://lists.apache.org/thread.html/r9584c4304c888f651d214341a939bd264ed30c9e3d0d30fe85097ecf%40%3Ccommits.pulsar.apache.org%3E
https://lists.apache.org/thread.html/r9a2cfa56d30782a0c17a5deb951a622d1f5c8de48e1c3b578ffc2a84%40%3Ccommits.pulsar.apache.org%3E
https://lists.apache.org/thread.html/ra8661fc8c69c647cb06153c1485d48484a833d873f75dfe45937e9de%40%3Ccommits.pulsar.apache.org%3E
https://lists.apache.org/thread.html/rbe1f230e87ea947593145d0072d0097ddb0af10fee1161db8ca1546c%40%3Ccommits.pulsar.apache.org%3E
https://lists.apache.org/thread.html/rd0e44e8ef71eeaaa3cf3d1b8b41eb25894372e2995ec908ce7624d26%40%3Ccommits.pulsar.apache.org%3E
https://lists.apache.org/thread.html/rd98cfd012490cb02caa1a11aaa0cc38bff2d43bcce9b20c2f01063dd%40%3Ccommits.pulsar.apache.org%3E
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/XE6US6VPZHOWFMUSFGDS5V2DNQPY5MKB/
https://www.oracle.com/security-alerts/cpuApr2021.html
https://www.oracle.com/security-alerts/cpuoct2020.html
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