CASCACascade Atlas

Evidence dossier

CVE-2023-37580

Zimbra Collaboration (ZCS) 8 before 8.8.15 Patch 41 allows XSS in the Zimbra Classic Web Client.

Exploited in the wild (CISA KEV since Jul 27, 2023). NVD reports CVSS 3.1 6.1. EPSS estimates 46.7% exploit likelihood as of Aug 27, 2026.

71.6–73.1Priority evidence range
Evidence current through Aug 27, 2026, 6:09 PM UTC

As of Aug 27, 2026

Normalized restatement

Zimbra Collaboration (ZCS) 8 before 8.8.15 Patch 41 allows XSS in the Zimbra Classic Web Client.

State
PUBLISHED
Published
Jul 31, 2023
Updated
Oct 30, 2025
Evidence coverage
99%

Evidence chronology

What was known when

Download this view's receipt →
  1. 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 ↗
  2. 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 ↗
  3. Source dateSource date omittedFirst observed by CASCA
    mitre

    Record text: Zimbra Collaboration (ZCS) 8 before 8.8.15 Patch 41 allows XSS in the Zimbra Classic Web Client.

    Inspect raw assertion
    Field
    container
    Value
    Zimbra Collaboration (ZCS) 8 before 8.8.15 Patch 41 allows XSS in the Zimbra Classic Web Client.
    Original evidence ↗
  4. 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 ↗
  5. Source dateFirst observed by CASCA
    FIRST EPSS

    EPSS score: 46.71% probability · 98.73th percentile

    Inspect raw assertion
    Field
    model_probability
    Value
    Probability 0.467090000000; percentile 0.987340000000
    Original evidence ↗
ExploitationCatalog member

CISA KEV · catalog date Jul 27, 2023 · first observed Jul 19, 2026

Exploit likelihood46.71%

FIRST EPSS · score date Aug 27, 2026 · 98.7th percentile · first observed Aug 27, 2026

SeverityCVSS 6.1

NVD · CVSS 3.1 · first observed Jul 19, 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 statusEvidence supported

Eligible evidence is present for this bounded claim.

Revision
evidence-policy-v1.1.0
Cutoff
Aug 27, 2026
Resolution
None
Exploit likelihoodEvidence supported

Eligible evidence is present for this bounded claim.

Revision
evidence-policy-v1.1.0
Cutoff
Aug 27, 2026
Resolution
None
Severity assessmentEvidence supported

Eligible evidence is present for this bounded claim.

Revision
casca-direct-cvss-eligibility-v1
Cutoff
Aug 27, 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
Aug 27, 2026
Resolution
Resolve identity

Source comparison

Who said what

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

Zimbra Collaboration (ZCS) 8 before 8.8.15 Patch 41 allows XSS in the Zimbra Classic Web Client.

Inspect raw assertion
Field
container
Value
Zimbra Collaboration (ZCS) 8 before 8.8.15 Patch 41 allows XSS in the Zimbra Classic Web Client.
Source dateSource date omittedFirst observed by CASCAOriginal evidence ↗
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 ↗
FIRST EPSSOriginal assertion
EPSS score

46.71% probability · 98.73th percentile

Inspect raw assertion
Field
model_probability
Value
Probability 0.467090000000; percentile 0.987340000000
Source dateFirst observed by CASCAOriginal evidence ↗

Applicability

Cited product scope

Trace impact →
14Underlying assertions
1Canonical products
14Target 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 · 14 assertions
Any version (unconstrained) (>= 8.8.0, < 8.8.15); Version 8.8.15Canonical identity product-4e282fadbbcc212039ad71a0e7de43d3b9757c46bbe8fd5c086551b6c01bb56aLinked exact
Scope supported
Inspect raw assertions
  1. cpe:2.3:a:synacor:zimbra_collaboration_suite:8.8.15:p31:*:*:*:*:*:*
    Official link
    Linked exact
    Role
    Vulnerable target
    Configuration
    0 · node/0 · match 5
    Logic
    OR
    Version bounds
    No explicit bounds
    Match ID
    fae2858a-6d9e-4d79-afa6-69c44d6d8c75
  2. cpe:2.3:a:synacor:zimbra_collaboration_suite:8.8.15:p34:*:*:*:*:*:*
    Official link
    Linked exact
    Role
    Vulnerable target
    Configuration
    0 · node/0 · match 8
    Logic
    OR
    Version bounds
    No explicit bounds
    Match ID
    89b3ef32-b474-44db-ae30-cd308cdc5a77
  3. 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
    from including 8.8.0; through excluding 8.8.15
    Match ID
    0696bce7-5351-4b01-9593-ba8bfb2d3a9e
  4. cpe:2.3:a:synacor:zimbra_collaboration_suite:8.8.15:p32:*:*:*:*:*:*
    Official link
    Linked exact
    Role
    Vulnerable target
    Configuration
    0 · node/0 · match 6
    Logic
    OR
    Version bounds
    No explicit bounds
    Match ID
    50a296bc-6da4-41b2-923a-0633566ad6c1
  5. cpe:2.3:a:synacor:zimbra_collaboration_suite:8.8.15:p38:*:*:*:*:*:*
    Official link
    Linked exact
    Role
    Vulnerable target
    Configuration
    0 · node/0 · match 11
    Logic
    OR
    Version bounds
    No explicit bounds
    Match ID
    64b28be5-f35d-4ab0-a321-ceae21bc26ff
  6. cpe:2.3:a:synacor:zimbra_collaboration_suite:8.8.15:p30:*:*:*:*:*:*
    Official link
    Linked exact
    Role
    Vulnerable target
    Configuration
    0 · node/0 · match 4
    Logic
    OR
    Version bounds
    No explicit bounds
    Match ID
    50fb0099-0495-4735-9398-7f7e657f459b
  7. cpe:2.3:a:synacor:zimbra_collaboration_suite:8.8.15:p37:*:*:*:*:*:*
    Official link
    Linked exact
    Role
    Vulnerable target
    Configuration
    0 · node/0 · match 10
    Logic
    OR
    Version bounds
    No explicit bounds
    Match ID
    518662da-c0f3-4875-86d7-5ed2b2496cc8
  8. cpe:2.3:a:synacor:zimbra_collaboration_suite:8.8.15:p3:*:*:*:*:*:*
    Official link
    Linked exact
    Role
    Vulnerable target
    Configuration
    0 · node/0 · match 3
    Logic
    OR
    Version bounds
    No explicit bounds
    Match ID
    ef2ee32d-04a5-46ea-92f0-3c8d74a4b82a
  9. cpe:2.3:a:synacor:zimbra_collaboration_suite:8.8.15:p5:*:*:*:*:*:*
    Official link
    Linked exact
    Role
    Vulnerable target
    Configuration
    0 · node/0 · match 13
    Logic
    OR
    Version bounds
    No explicit bounds
    Match ID
    a9a1314a-20c8-42d7-9387-d914999eeaf6
  10. cpe:2.3:a:synacor:zimbra_collaboration_suite:8.8.15:p35:*:*:*:*:*:*
    Official link
    Linked exact
    Role
    Vulnerable target
    Configuration
    0 · node/0 · match 9
    Logic
    OR
    Version bounds
    No explicit bounds
    Match ID
    a9eccb00-f3f4-4eb7-9fd0-4cb64678b129
  11. cpe:2.3:a:synacor:zimbra_collaboration_suite:8.8.15:p40:*:*:*:*:*:*
    Official link
    Linked exact
    Role
    Vulnerable target
    Configuration
    0 · node/0 · match 12
    Logic
    OR
    Version bounds
    No explicit bounds
    Match ID
    0d2d6dbd-560a-4f8e-b2cc-67a564c460a3
  12. cpe:2.3:a:synacor:zimbra_collaboration_suite:8.8.15:p33:*:*:*:*:*:*
    Official link
    Linked exact
    Role
    Vulnerable target
    Configuration
    0 · node/0 · match 7
    Logic
    OR
    Version bounds
    No explicit bounds
    Match ID
    c066ed38-1175-48fb-be05-be0c19e9ebe7
  13. cpe:2.3:a:synacor:zimbra_collaboration_suite:8.8.15:p11:*:*:*:*:*:*
    Official link
    Linked exact
    Role
    Vulnerable target
    Configuration
    0 · node/0 · match 1
    Logic
    OR
    Version bounds
    No explicit bounds
    Match ID
    7822d273-c2cb-4efe-b929-3d34c65e005e
  14. cpe:2.3:a:synacor:zimbra_collaboration_suite:8.8.15:p26:*:*:*:*:*:*
    Official link
    Linked exact
    Role
    Vulnerable target
    Configuration
    0 · node/0 · match 2
    Logic
    OR
    Version bounds
    No explicit bounds
    Match ID
    9bc02b35-7fc4-41ab-8d2e-2cd1896d84c6

Affected-product evidence

Accepted scope and product mapping

1 canonical links · 1 source-reported links

Mapping establishedEvidence supported

vendor-3d8b4bf53132b048a53e1d14e1e14dd5a07b75f8055a3624a0041d87433ca594 · product-4e282fadbbcc212039ad71a0e7de43d3b9757c46bbe8fd5c086551b6c01bb56a

Source class
Nvd cpe vulnerable target
Assertions
14
Mapping revision
cpe23-exact-mapping-v1
Observed cutoff
Aug 27, 2026
Retained assertion IDs
03d74ea2-ca5c-4c5d-9362-2c75dea2c6361f4da3f3-cd2b-46ef-b651-c42fd8e240783ada7c57-0608-4fff-9a21-fbc84c716fa23c851961-b020-4269-b528-afa10edb67f556f29c84-56ba-4268-bc6e-5a2212852a936d1575eb-0c6b-4240-86e2-800ec19eb6d081b283ef-d411-4685-965d-8161ea27cb3884e0e3aa-a247-42d4-ac78-6c852125e9c6926007df-9c17-41a6-b8b3-1034463e6dd2973de748-eab5-4a29-9951-a6ab06cd9185d18073b7-d143-41ae-b71c-1e9004771d6ce47e1574-faca-4d97-829e-d48cd348cc55f95c4b51-486e-4bb6-8526-cb05c2244e6cfd57ce48-20f9-4854-8e4f-326563bae278
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
Aug 27, 2026
Retained assertion IDs
b4fb0433-e312-41ec-8457-ce39020546dd

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
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.