Swift Foundation: Improper Neutralization of Special Elements in Output Used by a Downstream Component
CVE-2022-3918 is a high-severity improper neutralization of special elements in output used by a downstream component vulnerability in Swift Foundation from Swift Project, with a CVSS 3.1 base score of 8.8 out of 10. It can be exploited remotely over the network by an attacker with a low-privileged account, without any action from a user. Affected Swift Foundation versions: 5.7.2 and earlier. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 0.81% chance of exploitation within 30 days, higher than 57% of scored CVEs.
High severity with no evidence of exploitation so far.
What to do
- Check which version of Swift Foundation 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.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Swift Project | Swift Foundation | 5.7.2 and earlier | 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
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- LowA basic user account is enough.
- 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:L/UI:N/S:U/C:H/I:H/A:H. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 8.8 | High | NVD |
| CVSS 3.1 | 8.8 | High | CISA (ADP) |
Official description
A program using FoundationNetworking in swift-corelibs-foundation is potentially vulnerable to CRLF ( ) injection in URLRequest headers. In this vulnerability, a client can insert one or several CRLF sequences into a URLRequest header value. When that request is sent via URLSession to an HTTP server, the server may interpret the content after the CRLF as extra headers, or even a second request. For example, consider a URLRequest to http://example.com/ with the GET method. Suppose we set the URLRequest header "Foo" to the value "Bar Extra-Header: Added GET /other HTTP/1.1". When this request is sent, it will appear to the server as two requests: GET / HTTP/1.1 Foo: Bar Extra-Header: Added GET /other HTTP/1.1 In this manner, the client is able to inject extra headers and craft an entirely new request to a separate path, despite only making one API call in URLSession. If a developer has total control over the request and its headers, this vulnerability may not pose a threat. However, this vulnerability escalates if un-sanitized user input is placed in header values. If so, a malicious user could inject new headers or requests to an intermediary or backend server. Developers should be especially careful to sanitize user input in this case, or upgrade their version of swift-corelibs-foundation to include the patch below.
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.
- 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/apple/swift-corelibs-foundation/security/advisories/GHSA-4pp3-mpf2-rj63Mitigation, Third Party Advisory
Recent Improper Neutralization of Special Elements in Output Used by a Downstream Component vulnerabilities
- 7.5 High severity
- 7.5 High severity
- 7.8 High severity
- 9.8 Critical severity
- 8.8 High severity
- 7.8 High severity
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