Cisco RV Series Routers Deserialization of Untrusted Data
CVE-2019-15271 is a high-severity deserialization of untrusted data vulnerability in Cisco Small Business RV Series Router Firmware from Cisco, 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. CISA added it to the Known Exploited Vulnerabilities catalogue on June 8, 2022, which means attacks have been observed in the wild.
Attackers are already exploiting this vulnerability, according to CISA.
What to do
- Update Rv016 Multi-wan VPN Firmware to 4.2.3.10 or a later version.
- Update Rv042 Dual Wan VPN Firmware to 4.2.3.10 or a later version.
- Update Rv042g Dual Gigabit Wan VPN Firmware to 4.2.3.10 or a later version.
- CISA's required action: Apply updates per vendor instructions.
- Read the advisory on tools.cisco.com for workarounds and exact fixed builds.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Cisco | Cisco Small Business RV Series Router Firmware | Not specified in the record | Not stated |
| Cisco | Rv016 Multi-wan VPN Firmware | before 4.2.3.10 | 4.2.3.10 |
| Cisco | Rv042 Dual Wan VPN Firmware | before 4.2.3.10 | 4.2.3.10 |
| Cisco | Rv042g Dual Gigabit Wan VPN Firmware | before 4.2.3.10 | 4.2.3.10 |
| Cisco | Rv082 Dual Wan VPN Firmware | before 4.2.3.10 | 4.2.3.10 |
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 3.0 | 8.8 | High | CNA (cisco.com) |
| CVSS 2.0 | 9.0 | High | NVD |
Official description
A vulnerability in the web-based management interface of certain Cisco Small Business RV Series Routers could allow an authenticated, remote attacker to execute arbitrary commands with root privileges. The attacker must have either a valid credential or an active session token. The vulnerability is due to lack of input validation of the HTTP payload. An attacker could exploit this vulnerability by sending a malicious HTTP request to the web-based management interface of the targeted device. A successful exploit could allow the attacker to execute commands with root privileges.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Deserialization of Untrusted Data
The product deserializes untrusted data without sufficiently ensuring that the resulting data will be valid.
How developers prevent this class of flaw
- If available, use the signing/sealing features of the programming language to assure that deserialized data has not been tainted. For example, a hash-based message authentication code (HMAC) could be used to ensure that data has not been modified.
- When deserializing data, populate a new object rather than just deserializing. The result is that the data flows through safe input validation and that the functions are safe.
- Explicitly define a final object() to prevent deserialization.
More Deserialization of Untrusted Data vulnerabilities (CWE-502)
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
Advisories
Third-party and government advisories
- cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2019-15271US Government Resource
Other vulnerabilities in Cisco Small Business RV Series Router Firmware
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