Cisco IOS, XR, and XE Software Buffer Overflow
CVE-2018-0175 is a high-severity use of externally-controlled format string vulnerability in Cisco IOS, IOS XE, and IOS XR, with a CVSS 3.1 base score of 8.0 out of 10. It can be exploited from the same local network by an unauthenticated attacker, but only if a user takes part, for example by opening a link or file. Affected Cisco IOS, IOS XE, and IOS XR versions: Cisco IOS, IOS XE, and IOS XR. The record does not name a fixed version, so check the vendor advisory. CISA added it to the Known Exploited Vulnerabilities catalogue on March 3, 2022, which means attacks have been observed in the wild.
Attackers are already exploiting this vulnerability, according to CISA.
What to do
- Check which version of Cisco IOS, IOS XE, and IOS XR you run against the affected versions below, and install the vendor's latest release.
- CISA's required action: Apply updates per vendor instructions.
- Read the advisory on tools.cisco.com for workarounds and exact fixed builds.
- 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 |
|---|---|---|---|
| Cisco IOS, IOS XE, and IOS XR | Cisco IOS, IOS XE, and IOS XR | Cisco IOS, IOS XE, and IOS XR | Not stated |
| Cisco | iOS | 15.4\(3\)m4.1; 15.2\(4a\)ea5 and earlier; 15.2\(6\)e0a and earlier; 15.6.3m1 and earlier | Not stated |
| Cisco | iOS Xe | 15.4\(3\)m4.1; 15.2\(4a\)ea5 and earlier; 15.2\(6\)e0a and earlier; 15.6.3m1 and earlier | Not stated |
| Cisco | iOS Xr | 15.4\(3\)m4.1 | 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
- AdjacentThe attacker must be on the same local network segment.
- 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:A/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 | 8.0 | High | NVD |
| CVSS 3.1 | 8.0 | High | CISA (ADP) |
| CVSS 2.0 | 7.9 | High | NVD |
Official description
Format String vulnerability in the Link Layer Discovery Protocol (LLDP) subsystem of Cisco IOS Software, Cisco IOS XE Software, and Cisco IOS XR Software could allow an unauthenticated, adjacent attacker to cause a denial of service (DoS) condition or execute arbitrary code with elevated privileges on an affected device. Cisco Bug IDs: CSCvd73664.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Use of Externally-Controlled Format String
The product uses a function that accepts a format string as an argument, but the format string originates from an external source.
How developers prevent this class of flaw
- Choose a language that is not subject to this flaw.
- Ensure that all format string functions are passed a static string which cannot be controlled by the user, and that the proper number of arguments are always sent to that function as well. If at all possible, use functions that do not support the %n operator in format strings.
- Run compilers and linkers with high warning levels, since they may detect incorrect usage.
More Use of Externally-Controlled Format String vulnerabilities (CWE-134)
Timeline
- CVE record published.
- Added to CISA's Known Exploited Vulnerabilities catalogue.
- Deadline for US federal agencies to remediate, set by CISA.
- CISA published its SSVC assessment (exploitation: active, automatable: no, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Third-party and government advisories
- ics-cert.us-cert.gov/advisories/ICSA-18-107-03Third Party Advisory, US Government Resource
- ics-cert.us-cert.gov/advisories/ICSA-18-107-04Third Party Advisory, US Government Resource
- ics-cert.us-cert.gov/advisories/ICSA-18-107-05Third Party Advisory, US Government Resource
- cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2018-0175US Government Resource
Other vulnerabilities in Cisco IOS, IOS XE, and IOS XR
- 8.8 High severity
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