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CVE.org (no NVD analysis yet)· CNA rapid7

CVE-2026-50055: Zimbra Collaboration Suite Sieve Notify Filter Action Bypasses Mail Forwarding Restriction via Variable Expansion

Noroxi assessment

Priority: Monitor (action score 26/100)

  • Public proof-of-concept code exists (GitHub); there is no record of exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.36% (FIRST EPSS).
  • Anyone who can reach it over the internet can trigger it. A low-privileged account is enough. No user action is required. No special conditions are required; it is repeatable.
  • Fixed version: Zimbra Zimbra Collaboration Suite 10.1.20.
  • Mentioned 1 time in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Low priority for now. Upgrade to Zimbra Zimbra Collaboration Suite 10.1.20 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

A policy-enforcement flaw in Zimbra Collaboration Suite allows an authenticated user to bypass disabled mail forwarding by using a Sieve notify action to send copies of email content and headers to an arbitrary address.

MediumCVSS 6.5 · v3.1—Proof of concept Fix available
Published
Oct 8, 2026
Updated
Oct 8, 2026
EPSS
0.3% · 30th percentile

Report tools

JSON

Action score

26

Monitor

Low priority for now.

CVSS
26 / 40 · 6.5 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.3%

CISA SSVC decision

Exploitation
none
Automatable
no
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
—
CNA · rapid7
6.5
NVD has not scored this yet; the score shown is the CNA’s.

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • Proof of concept exists, no weaponized module
  • A fix has been released

If any of these changes, we'll tell you in the daily email digest.

Follow CVE-2026-50055

When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

—

Versions reported by the vendor

Affected version ranges reported by the assigning authority (rapid7). Independent of NVD's CPE analysis and usually ahead of it.

  • Zimbra Zimbra Collaboration Suite

    • before 10.1.20affected · semver

Same product

zimbra: all records

Other highest-scoring records for the same primary product.

  • CVE-2015-7610Cross-site request forgery (CSRF) vulnerability in the login form in Zimbra Collaboration Suite (aka ZCS) before 8.6.0 Patch 10, 8.7.x befor
    35Monitor
  • CVE-2026-93639Zimbra Collaboration Suite Missing Authorization in ConfigureZimlet Enables Delegated Administrator Privilege Escalation
    34Monitor
  • CVE-2026-10632Zimbra Collaboration Suite Classic Web Client Reflected Cross-Site Scripting via Document Editor Packages Parameter
    34Monitor

Published before and after this one in the same product

  • ← EarlierCVE-2026-10631Oct 8, 2026 · Zimbra Collaboration Suite EWS Extension Authorization Bypass via Crafted Composite Folder/Item Identifier
    26Monitor
  • ← EarlierCVE-2026-50054Oct 8, 2026 · Zimbra Collaboration Suite GrantRightsRequest SOAP Handler Allows Self-Granting of Undocumented loginAs Mailbox Delegation Right
    28Monitor
  • Later →CVE-2026-93635Oct 14, 2026 · Zimbra Collaboration Suite LDAP Filter Injection via Unescaped computeDn() Template Substitution
    21Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
Zimbra Zimbra Collaboration Suite10.1.20Vendor (CNA)

Exploit status

Proof of concept available

A public proof of concept or detection signature exists. Exploit knowledge is out there; don't delay patching.

Evidence

  • Proof-of-concept repository on GitHub ×1

Noroxi does not host or link to exploit code. Metasploit module names and Nuclei template ids are shown (names, not code); Exploit-DB entries and PoC repositories are given as counts only.

Public exploit evidence
SourceKindDate
Proof-of-concept repository on GitHubstars:02026-07-22

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

  1. First PoC-79 d
  2. Published
  3. Fix recordedsame day
  4. TodayNov 10, 2026+33 d
EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

National notice (Türkiye Cybersecurity Directorate / USOM)

Official security notices citing this record; remediation advice is on the agency's page.

All national notices →

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • A low-privileged account is enough.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
high · data can be read
Integrity
none
Availability
none
Attack vector
Network
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality impact
High
Integrity impact
None
Availability impact
None

Weakness class (CWE)

CWE-863 · Incorrect Authorization

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N

nvd-secondary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Change log

  1. Exploit maturity— → poc
  2. Fix✗ → ✓
  3. SSVC exploitation— → none

For records you follow, these changes also arrive as notifications. →

References

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records