CVE-2005-0468: Heap-based buffer overflow in the env_opt_add function in telnet.c for various BSD-based Telnet clients allows

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HIGH 7.5DOWNGRADE

CVE-2005-0468 is a high-severity flaw (CVSS 7.5) affecting telnet. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Heap-based buffer overflow in the env_opt_add function in telnet.c for various BSD-based Telnet clients allows remote attackers to execute arbitrary code via responses that contain a large number of characters that require escaping, which consumers more memory than allocated.

Why this priority

High severity
EPSS top 2%: very likely to be exploited
Public exploit reference

No fix is published yet: follow the downgrade or mitigation steps.

Risk facts

CVSS score	7.5 (High)
EPSS exploit chance	27.1% (top 2%)
CISA exploited list	No
Published	2005-05-02
Last modified	2026-06-16

Publisher (CNA): MITRE · Vendor: ncsa

Last updated 2026-06-16 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2005-05-02 04:00 UTCPublished CVE record published
2026-06-16 22:11 UTCUpdated Record last modified

ncsa telnet DOWNGRADE

Affected: c

Fixed in: no fixed release known

Safe to downgrade to: a release before c

1. Check installed version

apt-cache policy telnet || rpm -q telnet || telnet --version

2. No fixed release: DOWNGRADE to a release before c (Debian / Ubuntu)

apt-cache madison telnet sudo apt install telnet=<VERSION_BEFORE_c> sudo apt-mark hold telnet

2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list telnet sudo dnf downgrade telnet-<VERSION_BEFORE_c> sudo dnf versionlock add telnet

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Public exploits and detection

Public code exists for this CVE. Treat unpatched systems as at risk, and only run PoCs in a lab.

Exploit-DB: Multiple Vendor Telnet Client - Env_opt_add Heap Buffer Overflow

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2005-0468?

telnet: downgrade or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2005-0468 being exploited?

CVE-2005-0468 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2005-0468 affect?

CVE-2005-0468 affects telnet. Severity is high (CVSS 7.5). Heap-based buffer overflow in the env_opt_add function in telnet.c for various BSD-based Telnet clients allows remote attackers to execute arbitrary code via responses that contain a large number of characters that require escaping, which c

How urgent is CVE-2005-0468?

Priority 56/100. High severity; EPSS top 2%: very likely to be exploited; Public exploit reference

Related CVEs

CVE-2005-0469 HIGH 7.5 MITIGATE Buffer overflow in the slc_add_reply function in various BSD-based Telnet clients, when handling LINEMODE subo

References

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