CVE-2025-52559Network attack vector

Data exposure via unescaped digest link labels

Published Jul 2, 2025 · Updated Jul 2, 2025

Stored XSS in Zulip Server 2.0.0-rc1 through 10.3 allows remote authenticated users to read data from digest-preview viewers. The digest message header and new-channel renderer insert topic and channel names into HTML link strings without escaping them before safe rendering. Exploitation requires a crafted name and another user to open the rarely used /digest/ preview; the reported consequence is data exposure in that viewer's browser context.

CVSS severity6.8
Medium
EPSS probability0.25%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Stored XSS in Zulip Server 2.0.0-rc1 through 10.3 allows remote authenticated users to read data from digest-preview viewers. The digest message header and new-channel renderer insert topic and channel names into HTML link strings without escaping them before safe rendering. Exploitation requires a crafted name and another user to open the rarely used /digest/ preview; the reported consequence is data exposure in that viewer's browser context.

The record

CVE
CVE-2025-52559
Published
Jul 2, 2025
Updated
Jul 2, 2025
Vendor
Zulip
Product
Zulip
Classifications
CWE-79, T1189
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Jul 2, 2025CVE publishedPublication date reported by the CVE source.
  2. Jul 2, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=>= 2.0.0-rc1, < 10.4

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Zulip · Zulipversion=>= 2.0.0-rc1, < 10.4

Published CVSS scores

5.4NIST NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
6.8GitHub, Inc.CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:N/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1189Drive-by Compromise

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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