merou: Improper Neutralization of Special Elements in Output Used by a Downstream Component
CVE-2022-4768 is a critical-severity improper neutralization of special elements in output used by a downstream component vulnerability in merou from Dropbox, with a CVSS 3.1 base score of 9.8 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. There is no confirmed exploitation so far. EPSS estimates a 0.72% chance of exploitation within 30 days, higher than 55% of scored CVEs.
Critical severity: a successful attack would have severe impact.
What to do
- Check which version of merou you run against the affected versions below, and install the vendor's latest release.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
Affected products and versions
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
- LowNo special conditions are needed; the attack works reliably.
- 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:L/PR:N/UI:N/S:U/C:H/I:H/A:H. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 6.3 | Medium | CNA (vuldb.com) |
| CVSS 3.1 | 9.8 | Critical | NVD |
Official description
A vulnerability was found in Dropbox merou. It has been classified as critical. Affected is the function add_public_key of the file grouper/public_key.py of the component SSH Public Key Handler. The manipulation of the argument public_key_str leads to injection. It is possible to launch the attack remotely. The name of the patch is d93087973afa26bc0a2d0a5eb5c0fde748bdd107. It is recommended to apply a patch to fix this issue. VDB-216906 is the identifier assigned to this vulnerability.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Improper Neutralization of Special Elements in Output Used by a Downstream Component
The product constructs all or part of a command, data structure, or record using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify how it is parsed or interpreted when it is sent to a downstream component.
How developers prevent this class of flaw
- Programming languages and supporting technologies might be chosen which are not subject to these issues.
- Utilize an appropriate mix of allowlist and denylist parsing to filter control-plane syntax from all input.
Timeline
- CVE record published.
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
- github.com/dropbox/merou/commit/d93087973afa26bc0a2d0a5eb5c0fde748bdd107Third Party Advisory
- github.com/dropbox/merou/pull/673Third Party Advisory
Third-party and government advisories
- vuldb.com/?ctiid.216906Third Party Advisory
- vuldb.com/?id.216906Third Party Advisory
Recent Improper Neutralization of Special Elements in Output Used by a Downstream Component vulnerabilities
- 8.8 High severity
- 7.8 High severity
- 9.8 Critical severity
- 7.1 High severity
- 9.8 Critical severity
- 8.8 High severity
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