CVE-2020-10935Public exploitNetwork attack vector

Account takeover via unsafe local-link rewriting

Published Apr 20, 2020 · Updated Aug 4, 2024

Stored XSS in Zulip Server before 2.1.3 allows remote authenticated users to take over accounts through crafted Markdown links. The Markdown processor rewrites a same-origin-looking URL whose path begins with javascript: into an executable scheme instead of preserving a safe path. A recipient must click the stored link; the resulting script runs in that user's Zulip origin and can use the session and CSRF token to change the account email.

CVSS severity5.4
Medium
EPSS probability0.72%
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 before 2.1.3 allows remote authenticated users to take over accounts through crafted Markdown links. The Markdown processor rewrites a same-origin-looking URL whose path begins with javascript: into an executable scheme instead of preserving a safe path. A recipient must click the stored link; the resulting script runs in that user's Zulip origin and can use the session and CSRF token to change the account email.

The record

CVE
CVE-2020-10935
Published
Apr 20, 2020
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-79, T1204.001
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Apr 20, 2020CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

3.5NIST NVDAV:N/AC:M/Au:S/C:N/I:P/A:N
5.4NIST NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/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 exploitPublished

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1204.001User Execution: Malicious Link

Public exploit references

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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