CVE-2026-25742: Zulip is an open-source team collaboration tool

This week

MEDIUM 5.3REMOTEUPGRADE

CVE-2026-25742 is a medium-severity flaw (CVSS 5.3) affecting zulip. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Zulip is an open-source team collaboration tool. Prior to version 11.6, Zulip is an open-source team collaboration tool. From version 1.4.0 to before version 11.6, even after spectator access (enable_spectator_access / WEB_PUBLIC_STREAMS_ENABLED) is disabled, attachments originating from web-public streams can still be retrieved anonymously. As a result, file contents remain accessible even after public access is intended to be disabled. Similarl

Why this priority

Public exploit reference
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 76%)
CISA exploited list	No
Weakness	CWE-862
Published	2026-04-03
Last modified	2026-07-24

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

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

Am I affected?

Timeline

2026-04-03 21:17 UTCPublished CVE record published
2026-07-24 22:10 UTCUpdated Record last modified

zulip zulip UPGRADE

Affected: >= 1.4.0 and < 11.6

Fixed in: 11.6

Safe to downgrade to: a release before 1.4.0

1. Check installed version

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

2. UPGRADE to 11.6 (Debian / Ubuntu)

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

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade zulip

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 1.4.0 (Debian / Ubuntu)

apt-cache madison zulip sudo apt install zulip=<VERSION_BEFORE_1.4.0> sudo apt-mark hold zulip

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

dnf --showduplicates list zulip sudo dnf downgrade zulip-<VERSION_BEFORE_1.4.0> sudo dnf versionlock add zulip

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-2026-25742?

zulip: upgrade to 11.6. Exact commands for each OS are on this page.

Is CVE-2026-25742 being exploited?

CVE-2026-25742 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-2026-25742 affect?

CVE-2026-25742 affects zulip. Severity is medium (CVSS 5.3). Zulip is an open-source team collaboration tool. Prior to version 11.6, Zulip is an open-source team collaboration tool. From version 1.4.0 to before version 11.6, even after spectator access (enable_spectator_access / WEB_PUBLIC_STREAMS_EN

How urgent is CVE-2026-25742?

Priority 35/100. Public exploit reference; Remotely exploitable, no login, no user action

Related CVEs

CVE-2026-26058 MEDIUM 6.1 UPGRADE Zulip is an open-source team collaboration tool

References

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