CVE-2003-0826: lsh daemon (lshd) does not properly return from certain functions in (1) read_line.c, (2) channel_commands.c,

This week

HIGH 7.5DOWNGRADE

CVE-2003-0826 is a high-severity flaw (CVSS 7.5) affecting lsh. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

lsh daemon (lshd) does not properly return from certain functions in (1) read_line.c, (2) channel_commands.c, or (3) client_keyexchange.c when long input is provided, which could allow remote attackers to execute arbitrary code via a heap-based buffer overflow attack.

Why this priority

High severity
EPSS top 4%: 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	12.1% (top 4%)
CISA exploited list	No
Published	2003-10-06
Last modified	2026-06-16

Publisher (CNA): MITRE · Vendor: gnu

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

Am I affected?

Timeline

2003-10-06 04:00 UTCPublished CVE record published
2026-06-16 22:03 UTCUpdated Record last modified

gnu lsh DOWNGRADE

Affected: 1.4 · 1.4.1 · 1.4.2

Fixed in: no fixed release known

Safe to downgrade to: a release before 1.4

1. Check installed version

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

2. No fixed release: DOWNGRADE to a release before 1.4 (Debian / Ubuntu)

apt-cache madison lsh sudo apt install lsh=<VERSION_BEFORE_1.4> sudo apt-mark hold lsh

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

dnf --showduplicates list lsh sudo dnf downgrade lsh-<VERSION_BEFORE_1.4> sudo dnf versionlock add lsh

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: LSH 1.x - Remote Buffer Overflow (1)
Exploit-DB: LSH 1.x - Remote Buffer Overflow (2)

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-2003-0826?

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

Is CVE-2003-0826 being exploited?

CVE-2003-0826 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-2003-0826 affect?

CVE-2003-0826 affects lsh. Severity is high (CVSS 7.5). lsh daemon (lshd) does not properly return from certain functions in (1) read_line.c, (2) channel_commands.c, or (3) client_keyexchange.c when long input is provided, which could allow remote attackers to execute arbitrary code via a heap-b

How urgent is CVE-2003-0826?

Priority 55/100. High severity; EPSS top 4%: very likely to be exploited; Public exploit reference

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CVE-2005-0814 MEDIUM 5.0 DOWNGRADE Unknown vulnerability in lshd in Lysator LSH 1.x and 2.x before 2.0.1 allows remote attackers to cause a denia

References

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