CVE-2026-25529: Postal is an open source SMTP server

Q: How do I fix CVE-2026-25529?

postal: upgrade to 3.3.5. Exact commands for each OS are on this page.

Q: Is CVE-2026-25529 being exploited?

CVE-2026-25529 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2026-25529 affect?

CVE-2026-25529 affects postal. Severity is high (CVSS 8.1). Postal is an open source SMTP server. Postal versions less than 3.3.5 had a HTML injection vulnerability that allowed unescaped data to be included in the admin interface. The primary way for unescaped data to be added is via the API's "sen

Routine

HIGH 8.1UPGRADE

CVE-2026-25529 is a high-severity flaw (CVSS 8.1) affecting postal. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Postal is an open source SMTP server. Postal versions less than 3.3.5 had a HTML injection vulnerability that allowed unescaped data to be included in the admin interface. The primary way for unescaped data to be added is via the API's "send/raw" method. This could allow arbitrary HTML to be injected in to the page which may modify the page in a misleading way or allow for unauthorised javascript to be executed. Fixed in 3.3.5 and higher.

Why this priority

High severity

A fixed release or distro patch exists.

Risk facts

CVSS score	8.1 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	Low
User interaction	None
EPSS exploit chance	0.2% (top 85%)
CISA exploited list	No
Weakness	CWE-79
Published	2026-03-12
Last modified	2026-06-17

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

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

Am I affected?

Timeline

2026-03-12 17:16 UTCPublished CVE record published
2026-06-17 10:24 UTCUpdated Record last modified

postalserver postal UPGRADE

Affected: < 3.3.5

Fixed in: 3.3.5

Safe to downgrade to: no unaffected older release

1. Check installed version

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

2. UPGRADE to 3.3.5 (Debian / Ubuntu)

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

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade postal

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

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-2026-25529?

postal: upgrade to 3.3.5. Exact commands for each OS are on this page.

Is CVE-2026-25529 being exploited?

CVE-2026-25529 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-2026-25529 affect?

CVE-2026-25529 affects postal. Severity is high (CVSS 8.1). Postal is an open source SMTP server. Postal versions less than 3.3.5 had a HTML injection vulnerability that allowed unescaped data to be included in the admin interface. The primary way for unescaped data to be added is via the API's "sen

How urgent is CVE-2026-25529?

Priority 32/100. High severity

References

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