FortimailApplication · Fortinet
CVE-2021-26090
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedA missing release of memory after its effective lifetime vulnerability in the Webmail of FortiMail 6.4.0 through 6.4.4 and 6.2.0 through 6.2.6 may allow an unauthenticated remote attacker to exhaust available memory via specifically crafted login requests.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · high confidenceA memory leak vulnerability in FortiMail's Webmail component allows unauthenticated attackers to exhaust server memory by sending specially crafted login requests. The vulnerability affects versions 6.4.0-6.4.4 and 6.2.0-6.2.6, where memory allocated during login processing is not properly released after its effective lifetime.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE data
FortimailApplication
>= 6.2.0, <= 6.2.6>= 6.4.0, < 6.4.5CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Network
- Complexity
- Low
- Privileges
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- None
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Identify FortiMail versionRun the command 'get system status' on the FortiMail CLI or check System > Settings > About in the web GUIAffected if The displayed version is 6.2.0 through 6.2.6, or 6.4.0 through 6.4.4 (or any version < 6.4.5 when >= 6.4.0)
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Confirm Webmail component is accessibleVerify the FortiMail webmail interface is exposed by attempting to reach https://<fortimail-ip>/webmail or checking listening ports (80/443) with 'show system interface'Affected if Webmail is accessible on the network (ports 80 or 443 open)
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Check current memory usageRun 'execute system top' or 'get system performance status' on the FortiMail CLI to observe current memory utilizationAffected if Memory usage shows abnormal consumption or steady increase without release after login attempts
The environment is affected if FortiMail version is 6.2.0-6.2.6 or 6.4.0-6.4.4 and the Webmail interface is exposed to network attackers.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
From vendor data6.4.5
Apply Fortinet's patches for CVE-2021-26090 (available in FortiMail 6.4.5 and 6.2.7 and later) or upgrade to a supported version. Consider rate-limiting or blocking repeated failed login attempts as a temporary mitigation to reduce the attack surface.
Fix this in Fortimail
Scoped from the published advisory
- Consultation2.0 h
- Implementation1.0 h
- Testing3.0 h
- Review / QA1.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,936.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-26090 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2021-26090 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
- No weaponised exploit code, or anything meant to cause harm
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