Security readout for executives and security teams
Plain-English summary
CVE-2026-21642 is a medium-severity reflected cross-site scripting issue in Revive Adserver 6. A malicious link targeting the affected `banner-acl.php` or `channel-acl.php` scripts could execute script in a logged-in administrator's browser if that administrator visits the link.
Executive priority
Treat as a moderate-priority web application security issue. Prioritize remediation for internet-accessible Revive Adserver administrative deployments and environments with multiple privileged administrators.
Technical view
The source bundle describes a reflected XSS vulnerability, CWE-79, in Revive Adserver 6 affecting the `banner-acl.php` and `channel-acl.php` scripts. The CVSS 3.0 score is 6.1 with vector `AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N`, indicating network reachability, low attack complexity, no attacker privileges required, required user interaction, changed scope, and limited confidentiality/integrity impact.
Likely exposure
Organizations running Revive Adserver version 6 are the relevant exposure group. Practical risk is highest where Revive administrators are logged in and can be persuaded to open attacker-crafted links. The bundle does not identify other affected products or versions.
Exploitation context
The source bundle does not indicate known active exploitation, and KEV is false. Exploitation requires a logged-in administrator to visit a crafted URL; the impact is browser-side script execution in that administrator context. No exploit payloads or operational details are provided here.
Researcher notes
Reported through HackerOne by community member Patrick Lang. Evidence in the bundle supports reflected XSS in Revive Adserver 6 only. No fixed version, patch commit, workaround, or active exploitation evidence is included in the provided bundle.
Mitigation direction
- Check Revive Adserver vendor guidance and the linked advisory for an official fixed version or patch, because the bundle does not provide patch evidence.
- Upgrade or patch affected Revive Adserver 6 deployments if vendor guidance confirms a fixed release.
- Restrict access to Revive Adserver administrative interfaces to trusted networks or authenticated administrative channels where feasible.
- Warn administrators not to open untrusted links while authenticated to Revive Adserver.
- Review session, MFA, and administrative access controls to reduce impact if an administrator is targeted.
Validation and detection
- Inventory Revive Adserver deployments and confirm whether version 6 is in use.
- Confirm whether the affected `banner-acl.php` and `channel-acl.php` scripts are present in deployed Revive Adserver instances.
- Review vendor and HackerOne advisory information for fixed-version details before declaring remediation complete.
- Review web access logs for unusual requests to the affected scripts with unexpected or suspicious parameter content, without replaying payloads.
- After applying vendor remediation, perform authorized defensive XSS regression testing using safe internal procedures.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-79: User-session and phishing behavior lookup
Client-side and session-facing weaknesses should be reviewed alongside initial-access and user-execution behaviors. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCVE-2026-21642 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- Medium
- CVSS
- 6.1 (3.0)
- Known Exploited
- No
- Published
Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N2.82.7Primary CVE scoreVulnerability scoring details
Base CVSS 3.0 score
6.1MediumVector: CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
Source materials
- CVE List V5 sourceCVE List V5
- https://hackerone.com/reports/3470970CVE reference
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.