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What is CVE-2022-24903?A high-severity flaw in Rsyslog, explained.

High severity4 affected products
The short answer

CVE-2022-24903 is a high-severity flaw (CVSS 8.1) in Rsyslog, published on 6 May 2022. 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 3.9%. If you run an affected version, plan in the vendor’s fix.

Check if it affects you →How to fix it

Published 6 May 2022. Record last updated 7 November 2023. We keep this page's data up to date.

What it does

What is CVE-2022-24903? 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, change data and take it offline.

The official description

Rsyslog is a rocket-fast system for log processing. Modules for TCP syslog reception have a potential heap buffer overflow when octet-counted framing is used. This can result in a segfault or some other malfunction. As of our understanding, this vulnerability can not be used for remote code execution. But there may still be a slight chance for experts to do that. The bug occurs when the octet count is read. While there is a check for the maximum number of octets, digits are written to a heap buffer even when the octet count is over the maximum, This can be used to overrun the memory buffer. However, once the sequence of digits stop, no additional characters can be added to the buffer. In our opinion, this makes remote exploits impossible or at least highly complex. Octet-counted framing is one of two potential framing modes. It is relatively uncommon, but enabled by default on receivers. Modules `imtcp`, `imptcp`, `imgssapi`, and `imhttp` are used for regular syslog message reception. It is best practice not to directly expose them to the public. When this practice is followed, the risk is considerably lower. Module `imdiag` is a diagnostics module primarily intended for testbench runs. We do not expect it to be present on any production installation. Octet-counted framing is not very common. Usually, it needs to be specifically enabled at senders. If users do not need it, they can turn it off for the most important modules. This will mitigate the vulnerability.

What kind of flaw is it?

  • CWE-120Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')
  • CWE-1284Improper Validation of Specified Quantity in Input
CVSS 3.1 scoreHigh · 8.1

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 offHard: conditions must line up
  • Login needed firstNo login needed
  • Does someone have to clickNo, nobody has to do anything
  • What an attacker getsCan read data, change data and take it offline

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

Exploitation

Is CVE-2022-24903 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 3.9%. 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 days3.9%Its EPSS score, from the latest forecast

Timeline

  1. Published
  2. Record last updated
  3. Exploit likelihood jumped
  4. Exploit likelihood fell
How Precursor Intelligence ranks it
48out of 100Medium

CVE-2022-24903 scores 48. 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-2022-24903 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-2022-24903? 4 products.

The published record lists 4 products from 4 vendors. Versions are shown as published: "before 8.2204.1" means every version up to, but not including, 8.2204.1. If you run one of these, check your version, then go to the fix below.

Remediation

How do I fix CVE-2022-24903? 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

6 links
Precursor Intelligence

Does CVE-2022-24903 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.
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FAQ

Common questions, answered plainly.

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CVE-2022-24903 is a high-severity flaw in Rsyslog, published on 6 May 2022. 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, change data and take it offline.

It scores 8.1 out of 10 on the CVSS severity scale, which is high. Our risk score for CVE-2022-24903 is 48 out of 100, which is Medium. Its action is "Plan remediation". No sign of exploitation and a low forecast. Patch it in your normal update cycle.

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 3.9%. That can change at any time, which is why we keep watching.

For Rsyslog: before 8.2204.1. The record lists 4 products in all, each with its versions, under "Who is affected" on this page.

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.

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