# CVE-2011-4862: Memory corruption in n/a

> Remote attackers can execute arbitrary code via a buffer overflow in the telnetd encryption key handling, affecting multiple operating systems and Kerberos implementations.

- **Severity:** Critical 10.0 (`AV:N/AC:L/Au:N/C:C/I:C/A:C`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 25 Dec 2011
- **Updated:** 7 Aug 2024
- **Also known as:** DEBIAN-CVE-2011-4862, DSA-2372-1, DSA-2373-1, DSA-2375-1, GHSA-x8cr-m6vm-pqh4, RHSA-2011:1851, RHSA-2011:1852, RHSA-2011:1853, RHSA-2011:1854

## What is CVE-2011-4862?

CVE-2011-4862 is a critical memory corruption vulnerability in Debian Debian Linux, published on 25 Dec 2011. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Buffer overflow in libtelnet/encrypt.c in telnetd in FreeBSD 7.3 through 9.0, MIT Kerberos Version 5 Applications (aka krb5-appl) 1.0.2 and earlier, Heimdal 1.5.1 and earlier, GNU inetutils, and possibly other products allows remote attackers to execute arbitrary code via a long encryption key, as exploited in the wild in December 2011.

Weakness: CWE-120 (Buffer Copy without Checking Size of Input)

## Which versions are affected by CVE-2011-4862?

It affects 10 products.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `krb5` | Red Hat:enterprise_linux:4::as | All versions | 0:1.3.4-65.el4 |
| `krb5-debuginfo` | Red Hat:enterprise_linux:4::as | All versions | 0:1.3.4-65.el4 |
| `krb5-devel` | Red Hat:enterprise_linux:4::as | All versions | 0:1.3.4-65.el4 |
| `krb5-libs` | Red Hat:enterprise_linux:4::as | All versions | 0:1.3.4-65.el4 |
| `krb5-server` | Red Hat:enterprise_linux:4::as | All versions | 0:1.3.4-65.el4 |
| `krb5-workstation` | Red Hat:enterprise_linux:4::as | All versions | 0:1.3.4-65.el4 |
| `krb5` | Red Hat:enterprise_linux:4::desktop | All versions | 0:1.3.4-65.el4 |
| `krb5-debuginfo` | Red Hat:enterprise_linux:4::desktop | All versions | 0:1.3.4-65.el4 |
| `krb5-devel` | Red Hat:enterprise_linux:4::desktop | All versions | 0:1.3.4-65.el4 |
| `krb5-libs` | Red Hat:enterprise_linux:4::desktop | All versions | 0:1.3.4-65.el4 |
| `krb5-server` | Red Hat:enterprise_linux:4::desktop | All versions | 0:1.3.4-65.el4 |
| `krb5-workstation` | Red Hat:enterprise_linux:4::desktop | All versions | 0:1.3.4-65.el4 |
| `krb5` | Red Hat:enterprise_linux:4::es | All versions | 0:1.3.4-65.el4 |
| `krb5-debuginfo` | Red Hat:enterprise_linux:4::es | All versions | 0:1.3.4-65.el4 |
| `krb5-devel` | Red Hat:enterprise_linux:4::es | All versions | 0:1.3.4-65.el4 |
| `krb5-libs` | Red Hat:enterprise_linux:4::es | All versions | 0:1.3.4-65.el4 |
| `krb5-server` | Red Hat:enterprise_linux:4::es | All versions | 0:1.3.4-65.el4 |
| `krb5-workstation` | Red Hat:enterprise_linux:4::es | All versions | 0:1.3.4-65.el4 |
| `krb5` | Red Hat:enterprise_linux:4::ws | All versions | 0:1.3.4-65.el4 |
| `krb5-debuginfo` | Red Hat:enterprise_linux:4::ws | All versions | 0:1.3.4-65.el4 |
| `krb5-devel` | Red Hat:enterprise_linux:4::ws | All versions | 0:1.3.4-65.el4 |
| `krb5-libs` | Red Hat:enterprise_linux:4::ws | All versions | 0:1.3.4-65.el4 |
| `krb5-server` | Red Hat:enterprise_linux:4::ws | All versions | 0:1.3.4-65.el4 |
| `krb5-workstation` | Red Hat:enterprise_linux:4::ws | All versions | 0:1.3.4-65.el4 |
| `krb5` | Red Hat:enterprise_linux:5::client | All versions | 0:1.6.1-63.el5_7 |
| `krb5-debuginfo` | Red Hat:enterprise_linux:5::client | All versions | 0:1.6.1-63.el5_7 |
| `krb5-libs` | Red Hat:enterprise_linux:5::client | All versions | 0:1.6.1-63.el5_7 |
| `krb5-workstation` | Red Hat:enterprise_linux:5::client | All versions | 0:1.6.1-63.el5_7 |
| `krb5` | Red Hat:enterprise_linux:5::client_workstation | All versions | 0:1.6.1-63.el5_7 |
| `krb5-debuginfo` | Red Hat:enterprise_linux:5::client_workstation | All versions | 0:1.6.1-63.el5_7 |
| `krb5-devel` | Red Hat:enterprise_linux:5::client_workstation | All versions | 0:1.6.1-63.el5_7 |
| `krb5-server` | Red Hat:enterprise_linux:5::client_workstation | All versions | 0:1.6.1-63.el5_7 |
| `krb5-server-ldap` | Red Hat:enterprise_linux:5::client_workstation | All versions | 0:1.6.1-63.el5_7 |
| `krb5` | Red Hat:enterprise_linux:5::server | All versions | 0:1.6.1-63.el5_7 |
| `krb5-debuginfo` | Red Hat:enterprise_linux:5::server | All versions | 0:1.6.1-63.el5_7 |
| `krb5-devel` | Red Hat:enterprise_linux:5::server | All versions | 0:1.6.1-63.el5_7 |
| `krb5-libs` | Red Hat:enterprise_linux:5::server | All versions | 0:1.6.1-63.el5_7 |
| `krb5-server` | Red Hat:enterprise_linux:5::server | All versions | 0:1.6.1-63.el5_7 |
| `krb5-server-ldap` | Red Hat:enterprise_linux:5::server | All versions | 0:1.6.1-63.el5_7 |
| `krb5-workstation` | Red Hat:enterprise_linux:5::server | All versions | 0:1.6.1-63.el5_7 |

Products: Debian Debian Linux, Fedoraproject Fedora, Freebsd Freebsd, Gnu Inetutils, Heimdal Project Heimdal, Mit Krb5-Appl, Opensuse Opensuse, Suse Linux Enterprise Desktop, Suse Linux Enterprise Server, Suse Linux Enterprise Software Development Kit.

## How do I fix CVE-2011-4862?

Apply the vendor's patch.

## Is CVE-2011-4862 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2011-4862 exists.

Public exploit code:

- Go Exploit for CVE-2011-4862 (github_poc): https://github.com/hdbreaker/GO-CVE-2011-4862
- Final Project for Security and Privacy CS 600.443 (github_poc): https://github.com/appsecrani/CVE-2011-4862
- FreeBSD Telnet Service Encryption Key ID Buffer Overflow (metasploit)
- Linux BSD-derived Telnet Service Encryption Key ID Buffer Overflow (metasploit)
- TelnetD encrypt_keyid - Function Pointer Overwrite (exploitdb)
- Linux BSD-derived Telnet Service Encryption Key ID - Remote Buffer Overflow (Metasploit) (exploitdb)

## Other vulnerabilities in Debian Debian Linux

- [CVE-2015-3306](https://insights.sbomify.com/CVE-2015-3306/): ProFTPD Improper Access Control (critical 10.0, exploited in the wild)
- [CVE-2025-49113](https://insights.sbomify.com/CVE-2025-49113/): RoundCube Webmail Deserialization of Untrusted Data (critical 9.9, exploited in the wild)
- [CVE-2026-24061](https://insights.sbomify.com/CVE-2026-24061/): GNU InetUtils Argument Injection (critical 9.8, exploited in the wild)
- [CVE-2025-39682](https://insights.sbomify.com/CVE-2025-39682/): Linux Kernel Improper Check for Unusual or Exceptional Conditions (critical 9.8, exploited in the wild)
- [CVE-2024-9680](https://insights.sbomify.com/CVE-2024-9680/): Mozilla Firefox Use-After-Free (critical 9.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2011-4862 and fix it if it is affected.

What it is: CVE-2011-4862 is a critical memory corruption vulnerability in Debian Debian Linux, published on 25 Dec 2011. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2011-4862 exists.

Affected product: Debian Debian Linux. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2011-4862/ (Markdown: https://insights.sbomify.com/CVE-2011-4862/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2011-4862
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2011-4862
- OSV: https://osv.dev/vulnerability/CVE-2011-4862

---
From sbomify Insights: https://insights.sbomify.com/CVE-2011-4862/
Summaries are generated and may contain mistakes; the official description above is the record.