Sign inStart freeBook a demo

What is CVE-2019-17638?A critical-severity flaw in Jetty, explained.

Critical severity1 affected product
The short answer

CVE-2019-17638 is a critical-severity flaw (CVSS 9.4) in Jetty from Eclipse, published on 9 July 2020. It is not on the list of flaws known to be exploited today. The latest forecast puts its chance of use in the next 30 days at 11%. If you run an affected version, plan in the vendor’s fix.

Check if it affects you →How to fix it

Published 9 July 2020. Record last updated 7 November 2023. We keep this page's data up to date.

What it does

What is CVE-2019-17638? In plain terms.

It can be attacked from anywhere on the internet without logging in, and nobody has to click anything. If it works, the attacker can read data and change data.

The official description

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).

What kind of flaw is it?

  • CWE-672Operation on a Resource after Expiration or Release
  • CWE-675Multiple Operations on Resource in Single-Operation Context
CVSS 3.1 scoreCritical · 9.4

How an attack on it works

Read straight from its severity rating, translated out of the shorthand.

  • Where an attacker can beAnywhere on the internet
  • How hard it is to pull offEasy: no special conditions
  • Login needed firstNo login needed
  • Does someone have to clickNo, nobody has to do anything
  • What an attacker getsCan read data and change data

Severity vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:L

Exploitation

Is CVE-2019-17638 being exploited? Not that we know of.

It is not on the list of flaws known to be exploited today. The latest forecast puts the chance of it being used in the next 30 days at 11%. That can change at any time, which is why we keep watching.

Known to be exploitedNoNot on the list of exploited flaws today
Chance of use in the next 30 days11%Its EPSS score, from the latest forecast

Timeline

  1. Published
  2. Record last updated
  3. Exploit likelihood fell
How Precursor Intelligence ranks it
54out of 100Medium

CVE-2019-17638 scores 54. Action: Plan remediation.

We keep the score of every published flaw up to date as the evidence changes. Four things go into the score, and evidence that criminals are actually using it counts most. In order:

  • Evidence it is being exploitedBiggest factor
  • How severe it isStrong factor
  • How widely exposed it isSmaller factor
  • Threat activity around itSmaller factor

85 and above is Critical. Anything confirmed as exploited is always marked for an emergency patch, whatever its score.

When CVE-2019-17638 matches software you track, it lands in your list with its score and the reasons behind it.

See your own ranked list →
Affected products

Who is affected by CVE-2019-17638? One product.

The published record lists 1 product from 1 vendor. If you run one of these, check your version, then go to the fix below.

  • Application

    Jetty

    by Eclipse

    Affected versions
    9.4.27-202002279.4.28-202004089.4.29-20200521
Remediation

How do I fix CVE-2019-17638? Four steps.

  1. Check whether you run itCompare your versions with the affected products above. Not sure what you run? Precursor Intelligence can work it out from your public website, or you can pick it from a list.
  2. Apply the vendor’s fixInstall the update named in the vendor’s advisory. We’ve put the advisory first in the list.
  3. If you can’t patch todayFollow any mitigation the vendor publishes, and limit who can reach the affected system from the internet until the update is in.
  4. Keep an eye on itTrack the product and we tell you as soon as we spot this flaw on the list of exploited flaws, or a jump in its exploit likelihood.

References

17 links
Precursor Intelligence

Does CVE-2019-17638 affect you? We'll keep checking.

Looking flaws up one at a time doesn't scale. Tell us what you run once, and we tell you which flaws matter to you, in what order, and keep watching for new ones.

  1. Tell us what you runPick your software from a list, or let us work it out from your website.
  2. We match it to every flawOver 400,000 published flaws, checked against your list.
  3. Ranked by real-world riskA 0 to 100 score, led by evidence criminals are using it.
  4. Told as soon as we knowAn alert by email, in the app or by webhook to your own tools.
Start free →Book a demo

Free plan, no card needed. Nothing to install.

FAQ

Common questions, answered plainly.

Something else? Talk to the team →

CVE-2019-17638 is a critical-severity flaw in Jetty from Eclipse, published on 9 July 2020. It can be attacked from anywhere on the internet without logging in, and nobody has to click anything. If it works, the attacker can read data and change data.

It scores 9.4 out of 10 on the CVSS severity scale, which is critical. Our risk score for CVE-2019-17638 is 54 out of 100, which is Medium. Its action is "Plan remediation". Not confirmed as exploited yet, but serious or likely enough that it should not wait for a quiet month.

It is not on the list of flaws known to be exploited today. The latest forecast puts the chance of it being used in the next 30 days at 11%. That can change at any time, which is why we keep watching.

For Jetty from Eclipse: 9.4.27-20200227, 9.4.28-20200408, 9.4.29-20200521.

Install the update the vendor names in its advisory, linked first under "How do I fix" on this page. If you can't patch today, follow the vendor's mitigation and limit who can reach the affected system from the internet.

Keep exploring