CVE-2026-54588: Poweradmin has Host Header Injection in OIDC redirect_uri, SAML ACS/SLO URL, and Logout Redirect Construction.

Should you act?

Critical and remotely reachable

No known exploitation yet, but it is network-reachable without credentials. This signal is computed from CISA KEV, EPSS and CVSS data; it is not an editorial verdict.

• No confirmed exploitation. It is not in CISA’s KEV catalog and CISA’s SSVC assessment records no known exploitation. That can change quickly after a public write-up; re-check if you are affected.
• EPSS 0.5%, percentile 45: FIRST’s model estimates a 0.5% chance of exploitation activity in the next 30 days, higher than 45% of all scored CVEs (low). EPSS is a probability, not a verdict.
• Needs a user to click or open something. Phishing makes that realistic, but it is not wormable.
• Only applies if your dependency tree includes poweradmin/poweradmin (Composer (PHP)) < 4.2.4, fixed in 4.2.4; poweradmin/poweradmin (Composer (PHP)) >= 4.3.0, < 4.3.3, fixed in 4.3.3. Check your lockfile, including transitive dependencies.

What it is

Poweradmin is a web-based DNS administration tool for PowerDNS server. Versions prior to 4.2.4 and 4.3.3 use the attacker-controlled HTTPHOST request header as the authoritative source for building callback URLs in its OIDC, SAML, and logout authentication flows without any validation. An unauthenticated attacker can poison the redirecturi sent to the Identity Provider, causing the IdP to redirect the victim's authorization code to an attacker-controlled server - resulting in full account takeover with no credentials required. Versions 4.2.4 and 4.3.3 patch the issue.

From the GitHub advisory

Summary Poweradmin v4.3.2 uses the attacker-controlled HTTPHOST request header as the authoritative source for building callback URLs in its OIDC, SAML, and logout authentication flows without any validation. An unauthenticated attacker can poison the redirecturi sent to the Identity Provider, causing the IdP to redirect the victim's authorization code to an attacker-controlled server - resulting in full account takeover with no credentials required.

Three independent code paths are affected:

- Primary (Critical): OidcService::getCallbackUrl() - redirecturi poisoning - Secondary (High): SamlConfigurationService::getBaseUrl() - SAML ACS/SLO URL poisoning - Tertiary (Medium): LogoutController::getBaseUrl() - post-logout redirect poisoning

Details

Root Cause

Weakness type: CWE-20, CWE-601.

Product: poweradmin/poweradmin (Composer (PHP)) · Assigned by: GitHub_M · Published: 2026-06-23

Affected and fixed versions

Severity scores

• Attack vector: network (remotely reachable)
• Attack complexity: low
• Privileges required: none (no login)
• User interaction: required (a user must click/open something)
• Scope: changed (can affect other components)

CVSS measures how bad a flaw is if exploited, not how likely exploitation is. Read it next to the exploitation data below.

Exploitation and urgency

• CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
• CISA SSVC assessment: exploitation none, automatable no, technical impact partial.
• FIRST EPSS (model of 2026-10-21): 0.54% probability of exploitation activity in the next 30 days; percentile 45.

Timeline

• 2026-06-23 — CVE record published by GitHub_M
• 2026-06-24 — CVE record last updated
• 2026-07-28 — GitHub-reviewed advisory GHSA-3735-5339-xfwx published (critical)

Sources and references

Original sources first. Version and fix details should always be confirmed against the vendor or project advisory.

Vulnerability records

1. GitHub Advisory GHSA-3735-5339-xfwx github.com
2. CVE.org record CVE-2026-54588 cve.org
3. NVD entry CVE-2026-54588 nvd.nist.gov

Other references from the CVE record and advisory

1. github.com github.com
2. github.com github.com
3. github.com github.com

Critical Composer (PHP) advisories · Today’s Security Digest