CVE-2026-45543: Nextcloud is an open source content collaboration platform

Routine

MEDIUM 5.3REMOTEUPGRADE

CVE-2026-45543 is a medium-severity flaw (CVSS 5.3) affecting forms. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Nextcloud is an open source content collaboration platform. From version 4.3.0 to before version 5.2.7, a removed collaborator retains unauthorized read access to uploaded respondent files for the affected form. The scope is limited to uploaded files for forms where that user previously had results access. This issue has been patched in version 5.2.7.

Why this priority

Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	5.3 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.3% (top 81%)
CISA exploited list	No
Weakness	CWE-552
Published	2026-06-01
Last modified	2026-07-22

Publisher (CNA): GitHub, Inc. · Vendor: nextcloud

Last updated 2026-07-22 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-06-01 19:16 UTCPublished CVE record published
2026-07-22 08:10 UTCUpdated Record last modified

nextcloud forms UPGRADE

Affected: >= 4.3.0 and < 5.2.7

Fixed in: 5.2.7

Safe to downgrade to: a release before 4.3.0

1. Check installed version

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

2. UPGRADE to 5.2.7 (Debian / Ubuntu)

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

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade forms

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 4.3.0 (Debian / Ubuntu)

apt-cache madison forms sudo apt install forms=<VERSION_BEFORE_4.3.0> sudo apt-mark hold forms

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

dnf --showduplicates list forms sudo dnf downgrade forms-<VERSION_BEFORE_4.3.0> sudo dnf versionlock add forms

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-2026-45543?

forms: upgrade to 5.2.7. Exact commands for each OS are on this page.

Is CVE-2026-45543 being exploited?

CVE-2026-45543 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-2026-45543 affect?

CVE-2026-45543 affects forms. Severity is medium (CVSS 5.3). Nextcloud is an open source content collaboration platform. From version 4.3.0 to before version 5.2.7, a removed collaborator retains unauthorized read access to uploaded respondent files for the affected form. The scope is limited to uplo

How urgent is CVE-2026-45543?

Priority 28/100. Remotely exploitable, no login, no user action

Software pages

Nextcloud vulnerabilities

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References

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