CVE-2026-48852: PuTTY 0.71 before 0.84 has an assertion failure in ECDSA signature verification.

Routine

LOW 3.7REMOTEUPGRADE

CVE-2026-48852 is a low-severity flaw (CVSS 3.7) affecting putty. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

PuTTY 0.71 before 0.84 has an assertion failure in ECDSA signature verification.

Why this priority

Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	3.7 (Low)
Attack vector	Network (remote)
Attack complexity	High
Privileges needed	None
User interaction	None
EPSS exploit chance	0.3% (top 80%)
CISA exploited list	No
Weakness	CWE-617
Published	2026-05-25
Last modified	2026-07-24

Publisher (CNA): MITRE · Vendor: putty

Last updated 2026-07-24 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-05-25 21:16 UTCPublished CVE record published
2026-07-24 10:10 UTCUpdated Record last modified

putty putty UPGRADE

Affected: >= 0.71 and < 0.84

Fixed in: 0.84

Safe to downgrade to: a release before 0.71

1. Check installed version

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

2. UPGRADE to 0.84 (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 0.71 (Debian / Ubuntu)

apt-cache madison putty sudo apt install putty=<VERSION_BEFORE_0.71> 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_0.71> 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.

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-2026-48852?

putty: upgrade to 0.84. Exact commands for each OS are on this page.

Is CVE-2026-48852 being exploited?

CVE-2026-48852 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-2026-48852 affect?

CVE-2026-48852 affects putty. Severity is low (CVSS 3.7). PuTTY 0.71 before 0.84 has an assertion failure in ECDSA signature verification.

How urgent is CVE-2026-48852?

Priority 23/100. Remotely exploitable, no login, no user action

Software pages

PuTTY vulnerabilities

Related CVEs

CVE-2026-48850 LOW 3.7 UPGRADE PuTTY 0.72 before 0.84 has a double free in RSA KEX.
CVE-2026-48851 LOW 3.1 UPGRADE PuTTY 0.77 before 0.84 uses a copy of the PuTTY icon as a trust indication for TELNET data but the trust statu

References

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