CVE-2004-1008: Integer signedness error in the ssh2_rdpkt function in PuTTY before 0.56 allows remote attackers to execute ar

This month

HIGH 10.0DOWNGRADEDOWNGRADE

CVE-2004-1008 is a high-severity flaw (CVSS 10.0) affecting putty, tortoisecvs. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Integer signedness error in the ssh2_rdpkt function in PuTTY before 0.56 allows remote attackers to execute arbitrary code via a SSH2_MSG_DEBUG packet with a modified stringlen parameter, which leads to a buffer overflow.

Why this priority

Critical severity
EPSS top 6%: very likely to be exploited

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

Risk facts

CVSS score	10.0 (High)
EPSS exploit chance	7.4% (top 6%)
CISA exploited list	No
Published	2005-01-10
Last modified	2026-06-16

Publisher (CNA): MITRE · Vendor: putty · tortoisecvs

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

Am I affected?

Timeline

2005-01-10 05:00 UTCPublished CVE record published
2026-06-16 22:06 UTCUpdated Record last modified

putty putty DOWNGRADE

Affected: 0.48 · 0.49 · 0.50 · 0.51 · 0.52 · 0.53 · 0.53b · 0.54

Fixed in: no fixed release known

Safe to downgrade to: a release before 0.48

1. Check installed version

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

2. No fixed release: DOWNGRADE to a release before 0.48 (Debian / Ubuntu)

apt-cache madison putty sudo apt install putty=<VERSION_BEFORE_0.48> sudo apt-mark hold putty

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

dnf --showduplicates list putty sudo dnf downgrade putty-<VERSION_BEFORE_0.48> sudo dnf versionlock add putty

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.

tortoisecvs tortoisecvs DOWNGRADE

Affected: 1.8

Fixed in: no fixed release known

Safe to downgrade to: a release before 1.8

1. Check installed version

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

2. No fixed release: DOWNGRADE to a release before 1.8 (Debian / Ubuntu)

apt-cache madison tortoisecvs sudo apt install tortoisecvs=<VERSION_BEFORE_1.8> sudo apt-mark hold tortoisecvs

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

dnf --showduplicates list tortoisecvs sudo dnf downgrade tortoisecvs-<VERSION_BEFORE_1.8> sudo dnf versionlock add tortoisecvs

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.

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-2004-1008?

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

Is CVE-2004-1008 being exploited?

CVE-2004-1008 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-2004-1008 affect?

CVE-2004-1008 affects putty, tortoisecvs. Severity is high (CVSS 10.0). Integer signedness error in the ssh2_rdpkt function in PuTTY before 0.56 allows remote attackers to execute arbitrary code via a SSH2_MSG_DEBUG packet with a modified stringlen parameter, which leads to a buffer overflow.

How urgent is CVE-2004-1008?

Priority 59/100. Critical severity; EPSS top 6%: very likely to be exploited

Software pages

PuTTY vulnerabilities

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References

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