CVE-2023-26756: The login page of Revive Adserver v5.4.1 is vulnerable to brute force attacks

This week

HIGH 7.5REMOTEDOWNGRADE

CVE-2023-26756 is a high-severity flaw (CVSS 7.5) affecting adserver. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

The login page of Revive Adserver v5.4.1 is vulnerable to brute force attacks. NOTE: The vendor's position is that this is effectively mitigated by rate limits and password-quality features.

Why this priority

High severity
Public exploit reference
Remotely exploitable, no login, no user action

No fix is published yet: follow the downgrade or mitigation steps.

Risk facts

CVSS score	7.5 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	1.2% (top 33%)
CISA exploited list	No
Weakness	CWE-307
Published	2023-04-14
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: revive

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

Am I affected?

Timeline

2023-04-14 12:15 UTCPublished CVE record published
2026-06-17 05:43 UTCUpdated Record last modified

revive adserver DOWNGRADE

Affected: 5.4.1

Fixed in: no fixed release known

Safe to downgrade to: a release before 5.4.1

1. Check installed version

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

2. No fixed release: DOWNGRADE to a release before 5.4.1 (Debian / Ubuntu)

apt-cache madison adserver sudo apt install adserver=<VERSION_BEFORE_5.4.1> sudo apt-mark hold adserver

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

dnf --showduplicates list adserver sudo dnf downgrade adserver-<VERSION_BEFORE_5.4.1> sudo dnf versionlock add adserver

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-2023-26756?

adserver: downgrade or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2023-26756 being exploited?

CVE-2023-26756 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-2023-26756 affect?

CVE-2023-26756 affects adserver. Severity is high (CVSS 7.5). The login page of Revive Adserver v5.4.1 is vulnerable to brute force attacks. NOTE: The vendor's position is that this is effectively mitigated by rate limits and password-quality features.

How urgent is CVE-2023-26756?

Priority 53/100. High severity; Public exploit reference; Remotely exploitable, no login, no user action

References

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