CVE-2024-31497: In PuTTY 0.68 through 0.80 before 0.81, biased ECDSA nonce generation allows an attacker to recover a user's N

Q: How do I fix CVE-2024-31497?

putty: upgrade to 0.81; filezilla client: upgrade to 3.67.0; winscp: upgrade to 6.3.3. Exact commands for each OS are on this page.

Q: Is CVE-2024-31497 being exploited?

CVE-2024-31497 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-2024-31497 affect?

CVE-2024-31497 affects putty, filezilla client, winscp. Severity is medium (CVSS 5.9). In PuTTY 0.68 through 0.80 before 0.81, biased ECDSA nonce generation allows an attacker to recover a user's NIST P-521 secret key via a quick attack in approximately 60 signatures. This is especially important in a scenario where an advers

Q: How urgent is CVE-2024-31497?

Priority 49/100. EPSS top 7%: very likely to be exploited; Remotely exploitable, no login, no user action

This month

MEDIUM 5.9REMOTEUPGRADEUPGRADEUPGRADE

CVE-2024-31497 is a medium-severity flaw (CVSS 5.9) affecting putty, filezilla client, winscp. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

In PuTTY 0.68 through 0.80 before 0.81, biased ECDSA nonce generation allows an attacker to recover a user's NIST P-521 secret key via a quick attack in approximately 60 signatures. This is especially important in a scenario where an adversary is able to read messages signed by PuTTY or Pageant. The required set of signed messages may be publicly readable because they are stored in a public Git service that supports use of SSH for commit signing,

Why this priority

EPSS top 7%: very likely to be exploited
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	5.9 (Medium)
Attack vector	Network (remote)
Attack complexity	High
Privileges needed	None
User interaction	None
EPSS exploit chance	5.7% (top 7%)
CISA exploited list	No
Weakness	CWE-338
Published	2024-04-15
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: fedoraproject · filezilla-project · putty · tigris · tortoisegit · winscp

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2024-04-15 20:15 UTCPublished CVE record published
2026-06-17 07:28 UTCUpdated Record last modified

putty putty UPGRADE

Affected: >= 0.68 and < 0.81

Fixed in: 0.81

Safe to downgrade to: a release before 0.68

1. Check installed version

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

2. UPGRADE to 0.81 (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.

3. If no update is available yet, DOWNGRADE to a release before 0.68 (Debian / Ubuntu)

apt-cache madison putty sudo apt install putty=<VERSION_BEFORE_0.68> sudo apt-mark hold putty

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list putty sudo dnf downgrade putty-<VERSION_BEFORE_0.68> 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.

filezilla-project filezilla client UPGRADE

Affected: < 3.67.0

Fixed in: 3.67.0

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy filezilla-client || rpm -q filezilla-client || filezilla-client --version

2. UPGRADE to 3.67.0 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade filezilla-client

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade filezilla-client

Note

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

winscp winscp UPGRADE

Affected: < 6.3.3

Fixed in: 6.3.3

Safe to downgrade to: no unaffected older release

1. Check installed version

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

2. UPGRADE to 6.3.3 (Debian / Ubuntu)

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

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade winscp

Note

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

tortoisegit tortoisegit UPGRADE

Affected: < 2.15.0.1

Fixed in: 2.15.0.1

Safe to downgrade to: no unaffected older release

1. Check installed version

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

2. UPGRADE to 2.15.0.1 (Debian / Ubuntu)

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

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade tortoisegit

Note

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

tigris tortoisesvn UPGRADE

Affected: < 1.14.6

Fixed in: 1.14.6

Safe to downgrade to: no unaffected older release

1. Check installed version

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

2. UPGRADE to 1.14.6 (Debian / Ubuntu)

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

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade tortoisesvn

Note

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

fedoraproject fedora MITIGATE

Affected: 38 · 39 · 40

Fixed in: no fixed release known

Safe to downgrade to: a release before 38

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

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-2024-31497?

putty: upgrade to 0.81; filezilla client: upgrade to 3.67.0; winscp: upgrade to 6.3.3. Exact commands for each OS are on this page.

Is CVE-2024-31497 being exploited?

CVE-2024-31497 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-2024-31497 affect?

CVE-2024-31497 affects putty, filezilla client, winscp. Severity is medium (CVSS 5.9). In PuTTY 0.68 through 0.80 before 0.81, biased ECDSA nonce generation allows an attacker to recover a user's NIST P-521 secret key via a quick attack in approximately 60 signatures. This is especially important in a scenario where an advers

How urgent is CVE-2024-31497?

Priority 49/100. EPSS top 7%: very likely to be exploited; Remotely exploitable, no login, no user action

Software pages

Git vulnerabilities · PuTTY vulnerabilities · FileZilla vulnerabilities

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References

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