Threats / Synacor / CVE-2023-34192
CVE-2023-34192
· EUVD no mirror located
· GCVE no mirror located
Verified 2026-08-04
Synacor Zimbra Collaboration Suite (ZCS) vulnerability
Synacor Zimbra Collaboration Suite contains a cross-site scripting vulnerability in the /h/autoSaveDraft function that allows authenticated attackers to execute arbitrary code.
Verdict
Today item — known-exploited.
A reflected or stored XSS flaw enables authenticated users to inject malicious scripts, potentially compromising session integrity, stealing credentials, or performing unauthorized actions within the collaboration platform.
CISA KEV Yes · 2025-02-254EPSS 0.77266 (verify live)5CVSS 9 (CISA)3CISA SSVC Exploitation: active · Automatable: no · Impact: total3Exploit Public PoC / detection · nuclei template11
01
Is it exploitable?
— the evidence, ranked above the scoreReported exploitation
3 independent public reports of in-the-wild exploitation are cataloged.Distinct reporting sources (vendor, incident response, government); open them for the underlying claims.
Exploited in the wild
Listed in the CISA Known Exploited Vulnerabilities catalog (added 2025-02-25).
Probability (EPSS)
EPSS 0.77266 — modeled likelihood of exploitation activity.EPSS is a daily-changing model output — open the source for today's value.
Severity / affected
CVSS 9 (CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:H) · Affected: Synacor, Zimbra Collaboration Suite (ZCS). Confirm exact fixed builds in the vendor advisory.CVSS — CISA-assigned via the ADP container (CVE.org), version 3.1; the CNA left no metrics, so CISA's own score is used ahead of NVD.
Weakness (CWE)
Mapped to CWE-79 Cross-site Scripting (XSS) — weakness family: Web / client.CWE assignment from the public NVD record (may be stale); the weakness class drives how the flaw is exploited.
CISA SSVC (triage disposition)
Exploitation: active · Automatable: no · Technical Impact: totalCISA's own stakeholder-specific triage inputs, published in the CVE record (CISA Coordinator role). NOTE: this is CISA's three decision points; the final Act/Attend/Track decision also requires a Mission & Well-being input not published here, so no overall decision is asserted.
Currency of the record
CISA added this to its KEV catalog 600 days after the CVE record was published.KEV lag = CISA-KEV dateAdded − CVE.org datePublished; a floor on how long the known-exploited flaw sat in the public record before the federal catalog listed it. Severity/weakness here is CNA- or CISA-assigned (current at disclosure), independent of NVD's analysis backlog.
Public exploit available
Public exploit tooling is catalogued for this CVE (a public proof-of-concept / detection template). Catalog entries: nuclei template. We link the catalog page(s) only — no payload or code is hosted or restated here.Link, never host — the catalog page is the source; basicsecurity.net does not redistribute payloads.
02
Who’s exploiting it?
— attribution turns risk into urgencyAttribution not established
No confirmed (advisory-backed) threat-actor attribution is established for this record. Absence of a named actor is not absence of compromise — see Coverage & confidence.
03
Why it matters
— the attack path, told twice: adversary, then board1
Front door — unauthenticated access narrative 1
Attacker
I craft a malicious script payload and inject it into the autoSaveDraft function parameter.
Business
User sessions and sensitive collaboration data become vulnerable to hijacking and unauthorized access.
2
Keys to the kingdom — privilege/identity takeover narrative 2
Attacker
I execute arbitrary JavaScript in the victim's browser context when they interact with the affected function.
Business
Attackers can steal authentication tokens, session cookies, or sensitive information stored in the web application.
3
Lateral reach — past segmentation narrative 3
Attacker
I perform actions on behalf of the authenticated user, such as modifying emails, calendar entries, or contacts.
Business
Data integrity is compromised and business operations relying on Zimbra are disrupted through unauthorized modifications.
04
What to do
— defensible action- Remediate per the vendor advisory — confirm the fixed build for your version and verify exposure.1
Say it to the boardA vulnerability with this evidence profile is a defensible budget line, not a backlog ticket — fund the change against the proof above.
05