CVE-2020-9760Network attack vector

Client crash via unresized nick-prefix buffers

Published Mar 23, 2020 · Updated Aug 4, 2024

Out-of-bounds write in WeeChat 0.3.4 through 2.7 allows remote attackers to crash the client via a crafted IRC 005 message. The IRC prefix parser replaces server->prefix_chars without resizing each channel nick's prefixes buffer, so a later nick-mode update writes beyond the old allocation. Exploitation requires the client to connect to a malicious IRC server that sends a second 005 response advertising longer nick prefixes; the vendor reports only a client crash.

CVSS severity7.5
High
EPSS probability2.25%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Out-of-bounds write in WeeChat 0.3.4 through 2.7 allows remote attackers to crash the client via a crafted IRC 005 message. The IRC prefix parser replaces server->prefix_chars without resizing each channel nick's prefixes buffer, so a later nick-mode update writes beyond the old allocation. Exploitation requires the client to connect to a malicious IRC server that sends a second 005 response advertising longer nick prefixes; the vendor reports only a client crash.

The record

CVE
CVE-2020-9760
Published
Mar 23, 2020
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-787, CWE-120, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 23, 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 privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

7.5WeeChatCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
7.5NIST NVDAV:N/AC:L/Au:N/C:P/I:P/A:P
9.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-787Out-of-bounds Write
CWE-120Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')
T1499.004Application or System Exploitation

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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