CVE-2013-4208: The rsa_verify function in PuTTY before 0.63 (1) does not clear sensitive process memory after use and (2) doe

Q: How do I fix CVE-2013-4208?

putty: downgrade or apply the listed mitigation; putty: upgrade to newer than 0.62. Exact commands for each OS are on this page.

Q: Is CVE-2013-4208 being exploited?

CVE-2013-4208 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2013-4208 affect?

CVE-2013-4208 affects putty, putty. Severity is low (CVSS 2.1). The rsa_verify function in PuTTY before 0.63 (1) does not clear sensitive process memory after use and (2) does not free certain structures containing sensitive process memory, which might allow local users to discover private RSA and DSA k

Q: How urgent is CVE-2013-4208?

Priority 16/100. No elevated risk signals yet.

Routine

LOW 2.1DOWNGRADEUPGRADE

CVE-2013-4208 is a low-severity flaw (CVSS 2.1) affecting putty, putty. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

The rsa_verify function in PuTTY before 0.63 (1) does not clear sensitive process memory after use and (2) does not free certain structures containing sensitive process memory, which might allow local users to discover private RSA and DSA keys.

Why this priority

No elevated risk signals yet

A fixed release or distro patch exists.

Risk facts

CVSS score	2.1 (Low)
EPSS exploit chance	0.4% (top 67%)
CISA exploited list	No
Weakness	CWE-200
Published	2013-08-19
Last modified	2026-06-16

Publisher (CNA): Red Hat, Inc. · Vendor: putty · simon tatham

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

Am I affected?

Timeline

2013-08-19 23:55 UTCPublished CVE record published
2026-06-16 23:56 UTCUpdated Record last modified

putty putty DOWNGRADE

Affected: 0.45 · 0.46 · 0.47 · 0.48 · 0.49 · 0.50 · 0.51 · 0.52

Fixed in: no fixed release known

Safe to downgrade to: a release before 0.45

1. Check installed version

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

2. No fixed release: DOWNGRADE to a release before 0.45 (Debian / Ubuntu)

apt-cache madison putty sudo apt install putty=<VERSION_BEFORE_0.45> sudo apt-mark hold putty

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

dnf --showduplicates list putty sudo dnf downgrade putty-<VERSION_BEFORE_0.45> 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.

simon tatham putty UPGRADE

Affected: <= 0.62 · 0.53

Fixed in: newer than 0.62

Safe to downgrade to: no unaffected older release

1. Check installed version

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

2. UPGRADE to newer than 0.62 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade putty

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade putty

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

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-2013-4208?

putty: downgrade or apply the listed mitigation; putty: upgrade to newer than 0.62. Exact commands for each OS are on this page.

Is CVE-2013-4208 being exploited?

CVE-2013-4208 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-2013-4208 affect?

CVE-2013-4208 affects putty, putty. Severity is low (CVSS 2.1). The rsa_verify function in PuTTY before 0.63 (1) does not clear sensitive process memory after use and (2) does not free certain structures containing sensitive process memory, which might allow local users to discover private RSA and DSA k

How urgent is CVE-2013-4208?

Priority 16/100. No elevated risk signals yet.

Software pages

PuTTY vulnerabilities

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References

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