https://github.com/curl/curl: Improper Neutralization of Special Elements in Output Used by a Downstream Component
CVE-2023-27533 is a high-severity improper neutralization of special elements in output used by a downstream component vulnerability in https://github.com/curl/curl, with a CVSS 3.1 base score of 8.8 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, but only if a user takes part, for example by opening a link or file. Affected https://github.com/curl/curl versions: Fixed in 8.0.0. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 2.16% chance of exploitation within 30 days, higher than 82% of scored CVEs.
High severity with no evidence of exploitation so far.
What to do
- Update SIMATIC S7-1500 CPU 1518-4 PN/DP MFP to V3.1.5 or a later version.
- Update SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP to V3.1.5 or a later version.
- Update SIPLUS S7-1500 CPU 1518-4 PN/DP MFP to V3.1.5 or a later version.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
- Because the attack needs a user to take part, warn users about unexpected links and files related to this product until it is patched.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Https://github.com/curl/curl | https://github.com/curl/curl | Fixed in 8.0.0 | Not stated |
| Siemens | SIMATIC S7-1500 CPU 1518-4 PN/DP MFP | V3.1.0 up to, but not including, V3.1.5 | V3.1.5 |
| Siemens | SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP | V3.1.0 up to, but not including, V3.1.5 | V3.1.5 |
| Siemens | SIPLUS S7-1500 CPU 1518-4 PN/DP MFP | V3.1.0 up to, but not including, V3.1.5 | V3.1.5 |
| Haxx | Curl | 7.0.0 through 7.881 | Not stated |
| Fedora Project | Fedora | 36 | Not stated |
| NetApp | Active Iq Unified Manager | Not specified in the record | Not stated |
| NetApp | Clustered Data Ontap | 9.0 | Not stated |
| NetApp | H300s Firmware | Not specified in the record | Not stated |
| NetApp | H500s Firmware | Not specified in the record | Not stated |
| NetApp | H700s Firmware | Not specified in the record | Not stated |
| NetApp | H410s Firmware | Not specified in the record | Not stated |
| Splunk | Universal Forwarder | 8.2.0 up to, but not including, 8.2.12; 9.0.0 up to, but not including, 9.0.6; 9.1.0 | 8.2.12, 9.0.6 |
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
- RequiredA user must take an action such as opening a file or link.
- 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:R/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 | 9.8 | Critical | CISA (ADP) |
Official description
A vulnerability in input validation exists in curl <8.0 during communication using the TELNET protocol may allow an attacker to pass on maliciously crafted user name and "telnet options" during server negotiation. The lack of proper input scrubbing allows an attacker to send content or perform option negotiation without the application's intent. This vulnerability could be exploited if an application allows user input, thereby enabling attackers to execute arbitrary code on the system.
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: poc, automatable: yes, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Third-party and government advisories
- lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/36NBD5YLJXXEDZLDGNFC…Mailing List, Third Party Advisory
- security.gentoo.org/glsa/202310-12Third Party Advisory
- security.netapp.com/advisory/ntap-20230420-0011/Third Party Advisory
Technical write-ups (may include proof of concept)
- hackerone.com/reports/1891474Exploit, Third Party Advisory
Other references
Other vulnerabilities in https://github.com/curl/curl
- 7.5 High severity
- 8.8 High severity
- 9.1 Critical severity
- 7.5 High severity
- 9.8 Critical severity
- 9.8 Critical severity
Recent Improper Neutralization of Special Elements in Output Used by a Downstream Component vulnerabilities
- 8.8 High severity
- 8.8 High severity
- 9.8 Critical severity
- 9.9 Critical severity
- 7.8 High severity
- 8.8 High severity
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