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Fencer Intel
critical 9.8

CVE-2011-2523 in the critical feed json

vsftpd 2.3.4 downloaded between 20110630 and 20110703 contains a backdoor which opens a shell on port 6200/tcp.

published 2019-11-27 6 y ago modified 2026-06-16 4 mo ago also EUVD-2011-2508

cvss
9.8
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
96.2%
EPSS 96.2% chance of exploitation in 30 days, percentile 99.8%
public exploits
3
Metasploit, Exploit-DB, plus a Nuclei check

Summary

vsftpd 2.3.4 downloaded between 20110630 and 20110703 contains a backdoor which opens a shell on port 6200/tcp.

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2011-2523 updated cvss 8.1

vsftpd: backdoor which opens a shell on port 6200/tcp

  • Red Hat Enterprise Linux 5 vsftpd Red Hat Enterprise Linux 6 vsftpd Red Hat Enterprise Linux 7 vsftpd, vsftpd-sysvinit Red Hat Enterprise Linux 8 vsftpd
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Timeline

  1. First public exploit (Metasploit exploit/unix/ftp/vsftpd_234_backdoor)
  2. Published

Exploit prediction

96.18% chance of exploitation in the next 30 days, higher than 99.8% of all scored CVEs (FIRST EPSS, 2026-11-09).

Exploits and checks

CVSS scores

assigned by version score vector
NVD 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
NVD 2.0 10.0 AV:N/AC:L/Au:N/C:C/I:C/A:C

Affected products

  • vsftpd vsftpd

Classification

Weakness
  • CWE-78 Improper Neutralization of Special Elements used in an OS Command

References

Sources

Fencer Intel 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.