rsyslog: Improper Validation of Specified Quantity in Input
CVE-2022-24903 is a high-severity improper validation of specified quantity in input vulnerability in rsyslog, with a CVSS 3.1 base score of 8.1 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. Affected rsyslog versions: < 8.2204.1. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 3.95% chance of exploitation within 30 days, which is in the top 9.42% of all scored CVEs.
High severity with no evidence of exploitation so far.
What to do
- Check which version of rsyslog you run against the affected versions below, and install the vendor's latest release.
- Read the advisory on github.com for workarounds and exact fixed builds.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Rsyslog | rsyslog | < 8.2204.1 | Not stated |
| Fedora Project | Fedora | 35 | Not stated |
| Debian | Debian Linux | 9.0; 10.0; 11.0 | Not stated |
| NetApp | Active Iq Unified Manager | Not specified in the record | Not stated |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- HighSuccess depends on conditions outside the attacker's control.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 8.1 | High | CNA (github.com) |
| CVSS 3.1 | 8.1 | High | NVD |
| CVSS 2.0 | 6.8 | Medium | NVD |
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.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Improper Validation of Specified Quantity in Input
The product receives input that is expected to specify a quantity (such as size or length), but it does not validate or incorrectly validates that the quantity has the required properties.
More Improper Validation of Specified Quantity in Input vulnerabilities (CWE-1284)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Advisories
- github.com/rsyslog/rsyslog/security/advisories/GHSA-ggw7-xr6h-mmr8Third Party Advisory
Patches and release notes
- github.com/rsyslog/rsyslog/commit/f211042ecbb472f9d8beb4678a65d272b6f07705Third Party Advisory
Third-party and government advisories
- lists.debian.org/debian-lts-announce/2022/05/msg00028.htmlMailing List, Third Party Advisory
- security.netapp.com/advisory/ntap-20221111-0002/Third Party Advisory
- debian.org/security/2022/dsa-5150Third Party Advisory
Other references
Other vulnerabilities in rsyslog
- 8.1 High severity
- 8.1 High severity
- 8.2 High severity
- 7.5 High severity
Recent Improper Validation of Specified Quantity in Input vulnerabilities
- 7.5 High severity
- 7.5 High severity
- 9.8 Critical severity
- 7.8 High severity
- 7.8 High severity
- 7.5 High severity
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