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CVE-2021-30477

MEDIUM

4.3

CVSS Score

Published: April 14, 2021 at 11:45 PM UTC

Updated: June 17, 2026 at 03:50 AM UTC

1 product affected across 1 vendorZulip Server

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Severity

MEDIUM4.3

Exploit prediction

EPSS 0.7%

Description

An issue was discovered in Zulip Server before 3.4. A bug in the implementation of replies to messages sent by outgoing webhooks to private streams meant that an outgoing webhook bot could be used to send messages to private streams that the user was not intended to be able to send messages to.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Zulip Server · Zulip

95%

v < 3.4

Affected range stops below 3.4, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

Patch and advisory references

https://blog.zulip.com/2021/04/14/zulip-server-3-4/

References (1)

x_refsource_MISCRelease NotesVendor Advisory

Source: [email protected]

https://blog.zulip.com/2021/04/14/zulip-server-3-4/

CVSS

4.3MEDIUM[email protected]

Attack Vector: NETWORK
Complexity: LOW
Privileges: LOW
User Interaction: NONE
Scope: UNCHANGED
Confidentiality: NONE
Integrity: LOW
Availability: NONE

Vector?

Quick Info

StatusMODIFIED

CWE

NVD-CWE-noinfo

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