CVE-2021-20134
CVE-2021-20134 is a high-severity vulnerability in Dlink Dir-2640-us Firmware with a CVSS 3.x base score of 8.4. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-22.
Key facts
- Severity: High (CVSS 3.x base score 8.4)
- CVSS v2: 7.4
- EPSS exploit prediction: 8% (94th percentile)
- Actively exploited: Not listed in CISA KEV
- Weakness: CWE-22
- Affected product: Dlink Dir-2640-us Firmware
- Published:
- Last modified:
Description
Quagga Services on D-Link DIR-2640 less than or equal to version 1.11B02 are affected by an absolute path traversal vulnerability that allows a remote, authenticated attacker to set an arbitrary file on the router's filesystem as the log file used by either Quagga service (zebra or ripd). Subsequent log messages will be appended to the file, prefixed by a timestamp and some logging metadata. Remote code execution can be achieved by using this vulnerability to append to a shell script on the router's filesystem, and then awaiting or triggering the execution of that script. A remote, unauthenticated root shell can easily be obtained on the device in this fashion.
Frequently asked questions
- What is CVE-2021-20134?
- Quagga Services on D-Link DIR-2640 less than or equal to version 1.11B02 are affected by an absolute path traversal vulnerability that allows a remote, authenticated attacker to set an arbitrary file on the router's filesystem as the log file used by either Quagga service (zebra or ripd). Subsequent log messages will be appended to the file, prefixed by a timestamp and some logging metadata. Remote code execution can be achieved by using this vulnerability to append to a shell script on the router's filesystem, and then awaiting or triggering the execution of that script. A remote, unauthenticated root shell can easily be obtained on the device in this fashion.
- How severe is CVE-2021-20134?
- CVE-2021-20134 has a CVSS 3.x base score of 8.4, rated high severity. It is exploitable over an adjacent network with low attack complexity, requires high privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
- Is CVE-2021-20134 being actively exploited?
- It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 8% (94th percentile), an estimate of the probability of exploitation in the next 30 days.
- What products are affected by CVE-2021-20134?
- CVE-2021-20134 affects Dlink Dir-2640-us Firmware. See the affected-products list for the exact vulnerable versions.
- How do I fix CVE-2021-20134?
- Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
- When was CVE-2021-20134 published?
- CVE-2021-20134 was published on 2021-12-30 and last updated on 2026-06-17.
References
Affected products (1)
- cpe:2.3:o:dlink:dir-2640-us_firmware:*:*:*:*:*:*:*:*
More vulnerabilities in Dlink Dir-2640-us Firmware
- CVE-2021-20132 — High (CVSS 8.8): Quagga Services on D-Link DIR-2640 less than or equal to version 1.11B02 use default hard-coded credentials, which can…
- CVE-2021-34203 — High (CVSS 8.1): D-Link DIR-2640-US 1.01B04 is vulnerable to Incorrect Access Control. Router ac2600 (dir-2640-us), when setting PPPoE,…
- CVE-2021-34202 — High (CVSS 7.8): There are multiple out-of-bounds vulnerabilities in some processes of D-Link AC2600(DIR-2640) 1.01B04. Ordinary…
- CVE-2021-34201 — High (CVSS 7.1): D-Link DIR-2640-US 1.01B04 is vulnerable to Buffer Overflow. There are multiple out-of-bounds vulnerabilities in some…
- CVE-2021-34204 — Medium (CVSS 6.8): D-Link DIR-2640-US 1.01B04 is affected by Insufficiently Protected Credentials. D-Link AC2600(DIR-2640) stores the…
- CVE-2021-20133 — Medium (CVSS 6.1): Quagga Services on D-Link DIR-2640 less than or equal to version 1.11B02 are affected by an absolute path traversal…
All CVEs affecting Dlink Dir-2640-us Firmware →
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