CASCACascade Atlas

Evidence dossier

CVE-2018-6882

Cross-site scripting (XSS) vulnerability in the ZmMailMsgView.getAttachmentLinkHtml function in Zimbra Collaboration Suite (ZCS) before 8.7 Patch 1 and 8.8.x before 8.8.7 might…

Exploited in the wild (CISA KEV since Apr 19, 2022). NVD reports CVSS 3.1 6.1. EPSS estimates 29.8% exploit likelihood as of Oct 22, 2026.

66.2–75.3Priority evidence range
Evidence through Oct 22, 2026, 6:07 PM UTC

As of Oct 22, 2026

Normalized restatement

Cross-site scripting (XSS) vulnerability in the ZmMailMsgView.getAttachmentLinkHtml function in Zimbra Collaboration Suite (ZCS) before 8.7 Patch 1 and 8.8.x before 8.8.7 might allow remote attackers to inject arbitrary web script or HTML via a Content-Location header in an email attachment.

State
PUBLISHED
Published
Mar 27, 2018
Updated
Oct 1, 2026
Evidence coverage
85%

Evidence chronology

What was known when

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  1. Source dateFirst observed by CASCA
    CISA KEV

    Exploitation cataloged: Synacor Zimbra Collaboration Suite (ZCS) Cross-Site Scripting (XSS) Vulnerability

    Inspect raw assertion
    Field
    observed_exploitation
    Value
    Synacor Zimbra Collaboration Suite (ZCS) Cross-Site Scripting (XSS) Vulnerability
    Original evidence ↗
  2. Source dateSource date omittedFirst observed by CASCA
    CISA-ADP

    Record text: CISA ADP Vulnrichment

    Inspect raw assertion
    Field
    container
    Value
    CISA ADP Vulnrichment
    Original evidence ↗
  3. Source dateSource date omittedFirst observed by CASCA
    CVE Program

    Record text: CVE Program Container

    Inspect raw assertion
    Field
    container
    Value
    CVE Program Container
    Original evidence ↗
  4. Source dateSource date omittedFirst observed by CASCA
    mitre

    Record text: Cross-site scripting (XSS) vulnerability in the ZmMailMsgView.getAttachmentLinkHtml function in Zimbra Collaboration Suite (ZCS) before 8.7 Patch 1 and 8.8.x before 8.8.7 might allow remote attackers to inject arbitrary web script or HTML via a Content-Location header in an email attachment.

    Inspect raw assertion
    Field
    container
    Value
    Cross-site scripting (XSS) vulnerability in the ZmMailMsgView.getAttachmentLinkHtml function in Zimbra Collaboration Suite (ZCS) before 8.7 Patch 1 and 8.8.x before 8.8.7 might allow remote attackers to inject arbitrary web script or HTML via a Content-Location header in an email attachment.
    Original evidence ↗
  5. Source dateFirst observed by CASCA
    FIRST EPSS

    EPSS score: 29.76% probability · 98.2th percentile

    Inspect raw assertion
    Field
    model_probability
    Value
    Probability 0.297610000000; percentile 0.982000000000
    Original evidence ↗
ExploitationCatalog member

CISA KEV · catalog date Apr 19, 2022 · first observed Sep 1, 2026

Exploit likelihood29.76%

FIRST EPSS · score date Oct 22, 2026 · 98.2th percentile · first observed Oct 22, 2026

SeverityCVSS 6.1

NVD · CVSS 3.1 · first observed Oct 2, 2026 · same-version scores align in this snapshot

Evidence detail

Source limits and decisions

Why each evidence state has this value

casca-unknown-reasons-v1
Exploitation statusLast verified source snapshot retained

The last verified source boundary remains in force for this claim.

Revision
evidence-policy-v1.1.0
Cutoff
Oct 22, 2026
Resolution
Review source contract
Exploit likelihoodEvidence supported

Eligible evidence is present for this bounded claim.

Revision
evidence-policy-v1.1.0
Cutoff
Oct 22, 2026
Resolution
None
Severity assessmentEvidence supported

Eligible evidence is present for this bounded claim.

Revision
casca-direct-cvss-eligibility-v1
Cutoff
Oct 22, 2026
Resolution
None
Affected productsSource-reported scope

The cited source assertion is retained while canonical product linkage remains open.

Revision
casca-factor-d-obligations-v1
Cutoff
Oct 22, 2026
Resolution
Resolve identity

Source comparison

Who said what

CISA KEVOriginal assertion
Exploitation cataloged

Synacor Zimbra Collaboration Suite (ZCS) Cross-Site Scripting (XSS) Vulnerability

Inspect raw assertion
Field
observed_exploitation
Value
Synacor Zimbra Collaboration Suite (ZCS) Cross-Site Scripting (XSS) Vulnerability
Source dateFirst observed by CASCAOriginal evidence ↗
CISA-ADPIndependent enrichment
Record text

CISA ADP Vulnrichment

Inspect raw assertion
Field
container
Value
CISA ADP Vulnrichment
Source dateSource date omittedFirst observed by CASCAOriginal evidence ↗
CVE ProgramDerivative copy
Record text

CVE Program Container

Inspect raw assertion
Field
container
Value
CVE Program Container
Source dateSource date omittedFirst observed by CASCAOriginal evidence ↗
mitreOriginal assertion
Record text

Cross-site scripting (XSS) vulnerability in the ZmMailMsgView.getAttachmentLinkHtml function in Zimbra Collaboration Suite (ZCS) before 8.7 Patch 1 and 8.8.x before 8.8.7 might allow remote attackers to inject arbitrary web script or HTML via a Content-Location header in an email attachment.

Inspect raw assertion
Field
container
Value
Cross-site scripting (XSS) vulnerability in the ZmMailMsgView.getAttachmentLinkHtml function in Zimbra Collaboration Suite (ZCS) before 8.7 Patch 1 and 8.8.x before 8.8.7 might allow remote attackers to inject arbitrary web script or HTML via a Content-Location header in an email attachment.
Source dateSource date omittedFirst observed by CASCAOriginal evidence ↗
FIRST EPSSOriginal assertion
EPSS score

29.76% probability · 98.2th percentile

Inspect raw assertion
Field
model_probability
Value
Probability 0.297610000000; percentile 0.982000000000
Source dateFirst observed by CASCAOriginal evidence ↗

Applicability

Cited product scope

Trace impact →
9Underlying assertions
1Canonical products
9Target assertions
0Constraint assertions

Grouped from 1 configuration nodes in this exact snapshot. Visual grouping is navigational; asset exposure and root cause require cited evidence.

Identity source boundaries
  • Cpe dictionary1,775,266 records · observed through 2026-07-21T06:45:29.809Z27d65b0f-b718-4b4f-bb79-c47c68d09dfa
  • Cpe match643,502 records · observed through 2026-07-21T08:13:17.697Z955dae73-7302-438b-aee1-058d7cc5d48e

2 scope groups

mitre · source assertedn/an/aDirect source scope
Affected: n/a
Source-reported scope

Canonical linkage remains open; the cited source assertion is retained below.

Inspect raw assertion[{"status": "affected", "version": "n/a"}]
NVD CPE · APPLICATIONsynacorzimbra_collaboration_suiteVulnerable target · 9 assertions
Any version (unconstrained) (< 8.7.0); Version 8.7.0; Version 8.8.0; Version 8.8.1; Version 8.8.2; Version 8.8.3; Version 8.8.4; Version 8.8.5; Version 8.8.6Canonical identity product-4e282fadbbcc212039ad71a0e7de43d3b9757c46bbe8fd5c086551b6c01bb56aLinked exact
Scope supported
Inspect raw assertions
  1. cpe:2.3:a:synacor:zimbra_collaboration_suite:8.8.4:*:*:*:*:*:*:*
    Official link
    Linked exact
    Role
    Vulnerable target
    Configuration
    0 · node/0 · match 6
    Logic
    OR
    Version bounds
    No explicit bounds
    Match ID
    8de425fc-5201-4eab-8b40-87da0f3b2120
  2. cpe:2.3:a:synacor:zimbra_collaboration_suite:8.8.1:*:*:*:*:*:*:*
    Official link
    Linked exact
    Role
    Vulnerable target
    Configuration
    0 · node/0 · match 3
    Logic
    OR
    Version bounds
    No explicit bounds
    Match ID
    5064c2c1-605a-4b35-8940-c824dc989aab
  3. cpe:2.3:a:synacor:zimbra_collaboration_suite:8.8.0:*:*:*:*:*:*:*
    Official link
    Linked exact
    Role
    Vulnerable target
    Configuration
    0 · node/0 · match 2
    Logic
    OR
    Version bounds
    No explicit bounds
    Match ID
    b8555354-ce05-4a50-9da6-f62f6a55ab12
  4. cpe:2.3:a:synacor:zimbra_collaboration_suite:*:*:*:*:*:*:*:*
    Official link
    Linked exact
    Role
    Vulnerable target
    Configuration
    0 · node/0 · match 0
    Logic
    OR
    Version bounds
    through excluding 8.7.0
    Match ID
    a915ddc5-0077-47ab-86a4-17221c708f7b
  5. cpe:2.3:a:synacor:zimbra_collaboration_suite:8.8.5:*:*:*:*:*:*:*
    Official link
    Linked exact
    Role
    Vulnerable target
    Configuration
    0 · node/0 · match 7
    Logic
    OR
    Version bounds
    No explicit bounds
    Match ID
    08b9acd5-1463-4c2e-8b13-de5f221bd1b6
  6. cpe:2.3:a:synacor:zimbra_collaboration_suite:8.7.0:-:*:*:*:*:*:*
    Official link
    Linked exact
    Role
    Vulnerable target
    Configuration
    0 · node/0 · match 1
    Logic
    OR
    Version bounds
    No explicit bounds
    Match ID
    384c4200-8b8a-497b-b3e7-7bbd44862b95
  7. cpe:2.3:a:synacor:zimbra_collaboration_suite:8.8.2:*:*:*:*:*:*:*
    Official link
    Linked exact
    Role
    Vulnerable target
    Configuration
    0 · node/0 · match 4
    Logic
    OR
    Version bounds
    No explicit bounds
    Match ID
    29a9742a-abe8-4307-995d-4ebbc9923d44
  8. cpe:2.3:a:synacor:zimbra_collaboration_suite:8.8.3:*:*:*:*:*:*:*
    Official link
    Linked exact
    Role
    Vulnerable target
    Configuration
    0 · node/0 · match 5
    Logic
    OR
    Version bounds
    No explicit bounds
    Match ID
    b7db501c-e7c8-4d87-a2fe-da52e1e66b39
  9. cpe:2.3:a:synacor:zimbra_collaboration_suite:8.8.6:*:*:*:*:*:*:*
    Official link
    Linked exact
    Role
    Vulnerable target
    Configuration
    0 · node/0 · match 8
    Logic
    OR
    Version bounds
    No explicit bounds
    Match ID
    ca0deb5b-4086-473f-be7e-ee2baecfa096

Affected-product evidence

Accepted scope and product mapping

0 canonical links · 2 source-reported links

Source-reported scopeSource-reported scope

Canonical linkage remains open; the cited source assertion is retained below.

Vendor specified only by source · Product specified only by source

Source class
Direct cve affected
Assertions
1
Mapping revision
cpe23-exact-mapping-v1
Observed cutoff
Oct 22, 2026
Retained assertion IDs
93fd1931-5f36-49a7-9bf2-cd1c96c4f742
Source-reported scopeSource-reported scope

Canonical linkage remains open; the cited source assertion is retained below.

Vendor specified only by source · Product specified only by source

Source class
Nvd cpe vulnerable target
Assertions
9
Mapping revision
cpe23-exact-mapping-v1
Observed cutoff
Oct 22, 2026
Retained assertion IDs
43ba40eb-fa6f-47b9-a65d-d84458a082594d9d1d4b-08cc-489f-859f-2bc1620abec6633fcdf3-2fd5-4dc2-8896-5df3fc83cb7e76e7c086-147c-4b05-a6a1-02e16b4325648d6ff494-fae5-4a30-9f66-d17fd468278a91e3c9e0-858c-4640-b829-8b57309b4e02ad2a8038-cd42-4798-9fa1-392b9c355dbdb94a5b47-9d4d-49be-8d75-d10a16fe8bf3fce9097b-7c07-4502-93b6-95f0137c5ee6

Assessments

CVSS by origin

6.1
NVDCVSS 3.1 · role Primary · priority eligiblevalid_matchCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
4.3
NVDCVSS 2.0 · role Primary · priority eligiblevalid_matchAV:N/AC:M/Au:N/C:N/I:P/A:N
6.1
CVE Program sourceCVSS 3.1 · role Secondary · priority eligiblevalid_matchCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
6.1
CISA-ADPCVSS 3.1 · role unknown · display onlyDirect record assessment retained outside normalized eligibilityCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

Direct CVE/CNA normalized decisions

6.1Priority eligible

CISA-ADP

CVSS 3.1 · Secondary · Independent enrichment · rank 2

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
Validation
Valid match
Recomputed
6.1
Decision reason
Evidence supported
Policy
casca-direct-cvss-eligibility-v1

Assessments are retained side by side under closed precedence. Cascade never averages CVSS.

Evidence boundaries

  • KEV membership is authoritative for the catalog, not proof of exposure in any environment.
  • EPSS is a dated model probability and not an individual-environment prediction.
  • Affected or fixed status applies only to the exact cited product and version scope; remaining scope stays source-scoped.
  • NVD-carried upstream facts remain derivative; independent corroboration requires a separately authored source.
  • Only NVD metrics validated under the generation-bound calculator are Public Priority eligible; direct CVE record metrics remain display-only.
  • NVD CVSS source eligibility is closed: NVD-authored, exact record-source, or registered same-CVE container origin; unmapped sources remain display-only.
  • Core replay supports the active and immediately prior generation; retrospective valid-at replay is deferred.
  • OSV aggregation and OSV-converted NVD material are not independent corroboration.
  • Red Hat facts are vendor assertions for the exact supplied products.
  • Nonmembership and not-yet-observed states are not proof of safety.