# CVE-2026-121551: PostfixAdmin through 4.0.5 Stored XSS via TOTP Exception Description

Status: published. Published: 2026-11-03. Updated: 2026-11-03.

PostfixAdmin through 4.0.5 contains a stored cross-site scripting vulnerability that allows authenticated mailbox users to inject script by creating a TOTP exception with an unescaped description. When a global administrator views totp-exceptions.php, the script runs in the admin session and can issue authenticated admin requests using the page's CSRF token.

## Remediation

- fix: The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches. (source: CNA: VulnCheck) — https://github.com/postfixadmin/postfixadmin/commit/0a894b08769481ce1a7f0f42af901c6d9f88fa9c
- fix: The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches. (source: CNA: VulnCheck) — https://github.com/postfixadmin/postfixadmin/pull/1172
- fix: The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches. (source: CNA: VulnCheck) — https://github.com/postfixadmin/postfixadmin/pull/1186

## Affected products and versions

- postfixadmin / postfixadmin (postfixadmin/postfixadmin): ≥ 0; ≤ 4.0.5 (affected, semver). Source: CNA: VulnCheck

## Severity and prioritization

- CVSS 4.0: 5.1 (medium); CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N; source: CNA: VulnCheck

- CVSS 3.1: 5.4 (medium); CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N; source: CNA: VulnCheck

- CVSS 4.0: 5.1 (medium); CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X; source: NVD: disclosure@vulncheck.com

- CVSS 3.1: 5.4 (medium); CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N; source: NVD: disclosure@vulncheck.com

- CISA KEV: No listing in collected sources

- EPSS: Not available

- SSVC: exploitation none; automatable no; technical impact partial; source ADP: CISA-ADP

- Weaknesses: CWE-79

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://github.com/postfixadmin/postfixadmin/issues/1185 (CNA: VulnCheck; issue-tracking)

- https://github.com/postfixadmin/postfixadmin (CNA: VulnCheck; product)

- https://github.com/postfixadmin/postfixadmin/commit/0a894b08769481ce1a7f0f42af901c6d9f88fa9c (CNA: VulnCheck; patch)

- https://github.com/postfixadmin/postfixadmin/blob/v4.0.5/public/users/totp-exceptions.php#L128 (CNA: VulnCheck; technical-description)

- https://github.com/postfixadmin/postfixadmin/blob/v4.0.5/templates/totp-exceptions.tpl#L56 (CNA: VulnCheck; technical-description)

- https://github.com/postfixadmin/postfixadmin/pull/1172 (CNA: VulnCheck; technical-description, patch, issue-tracking)

- https://github.com/postfixadmin/postfixadmin/pull/1186 (CNA: VulnCheck; technical-description, patch, issue-tracking)

- https://www.vulncheck.com/advisories/postfixadmin-through-4.0.5-stored-xss-via-totp-exception-description (CNA: VulnCheck; third-party-advisory)

- https://github.com/postfixadmin/postfixadmin (disclosure@vulncheck.com)

- https://github.com/postfixadmin/postfixadmin/blob/v4.0.5/public/users/totp-exceptions.php#L128 (disclosure@vulncheck.com)

- https://github.com/postfixadmin/postfixadmin/blob/v4.0.5/templates/totp-exceptions.tpl#L56 (disclosure@vulncheck.com)

- https://github.com/postfixadmin/postfixadmin/commit/0a894b08769481ce1a7f0f42af901c6d9f88fa9c (disclosure@vulncheck.com)

- https://github.com/postfixadmin/postfixadmin/issues/1185 (disclosure@vulncheck.com)

- https://github.com/postfixadmin/postfixadmin/pull/1172 (disclosure@vulncheck.com)

- https://github.com/postfixadmin/postfixadmin/pull/1186 (disclosure@vulncheck.com)

- https://www.vulncheck.com/advisories/postfixadmin-through-4.0.5-stored-xss-via-totp-exception-description (disclosure@vulncheck.com)

## Provenance

- CNA: VulnCheck: https://www.cve.org/CVERecord?id=CVE-2026-121551; retrieved 2026-11-03; source updated 2026-11-03

- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-121551; retrieved 2026-11-03; source updated 2026-11-03

Revision: e8d0b4eb1c7c30e505a800550b82fc4732c864f8d8b50e3620c633cd86e22631

Canonical: https://y2.dev/cve/CVE-2026-121551

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