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Fencer Vulns
high 8.4

CVE-2021-20134 json

Quagga Services on D-Link DIR-2640 less than or equal to version 1.11B02 are affected by an absolute path traversal vulnerability that allo…

published 2021-12-30 4 y ago modified 2026-06-17 4 mo ago also EUVD-2021-7591

cvss
8.4
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
7.8%
EPSS 7.8% chance of exploitation in 30 days, percentile 94%
public exploits
0
none known

Summary

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.

Exploit prediction

7.77% chance of exploitation in the next 30 days, higher than 94% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • tenable.com https://www.tenable.com/security/research/tra-2021-44 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
NVD 3.1 8.4 CVSS:3.1/AV:A/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H
NVD 2.0 7.4 AV:A/AC:M/Au:S/C:C/I:C/A:C

Affected products

  • n/a Quagga Services on D-Link DIR-2640 Routers

Classification

Weakness
  • CWE-22 Improper Limitation of a Pathname to a Restricted Directory

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.