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CVE-2021-40516

WeeChat before 3.2.1 allows remote attackers to cause a denial of service (crash) via a crafted...

7.5 HighFix available

WeeChat before 3.2.1 allows remote attackers to cause a denial of service (crash) via a crafted WebSocket frame that trigger an out-of-bounds read in plugins/relay/relay-websocket.c in the Relay plugin.

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
Low
Privileges needed
None
User interaction
None

What an attacker can affect

Confidentiality
None
Integrity
None
Availability
High

Exploit likelihood

1.59%Up 0.6 points since Sep 6, 2021
90%50%10%1%

What each source reports

NVD Score used 7.5

WeeChat before 3.2.1 allows remote attackers to cause a denial of service (crash) via a crafted WebSocket frame that trigger an out-of-bounds read in plugins/relay/relay-websocket.c in the Relay plugin.

Record
CVE-2021-40516
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CVSS 2.0
5.0 MediumAV:N/AC:L/Au:N/C:N/I:N/A:P
Weakness
CWE-125
Updated
2026-11-02
CVE List No score

WeeChat before 3.2.1 allows remote attackers to cause a denial of service (crash) via a crafted WebSocket frame that trigger an out-of-bounds read in plugins/relay/relay-websocket.c in the Relay plugin.

Record
CVE-2021-40516
Updated
2026-11-02
EUVDEUVD-2021-27692 No score

WeeChat before 3.2.1 allows remote attackers to cause a denial of service (crash) via a crafted WebSocket frame that trigger an out-of-bounds read in plugins/relay/relay-websocket.c in the Relay plugin.

Record
EUVD-2021-27692
Updated
2026-11-03
GitHub AdvisoriesGHSA-82mm-45xg-j4xh No score

WeeChat before 3.2.1 allows remote attackers to cause a denial of service (crash) via a crafted...

WeeChat before 3.2.1 allows remote attackers to cause a denial of service (crash) via a crafted WebSocket frame that trigger an out-of-bounds read in plugins/relay/relay-websocket.c in the Relay plugin.

Record
GHSA-82mm-45xg-j4xh
Weakness
CWE-125
Updated
2026-11-02
OSVALPINE-CVE-2021-40516 7.5

WeeChat before 3.2.1 allows remote attackers to cause a denial of service (crash) via a crafted WebSocket frame that trigger an out-of-bounds read in plugins/relay/relay-websocket.c in the Relay plugin.

Record
ALPINE-CVE-2021-40516
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Updated
2026-11-03
OSV 7.5

WeeChat before 3.2.1 allows remote attackers to cause a denial of service (crash) via a crafted WebSocket frame that trigger an out-of-bounds read in plugins/relay/relay-websocket.c in the Relay plugin.

Record
CVE-2021-40516
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Updated
2026-11-02
Show 5 moreShow less
OSVDEBIAN-CVE-2021-40516 7.5

WeeChat before 3.2.1 allows remote attackers to cause a denial of service (crash) via a crafted WebSocket frame that trigger an out-of-bounds read in plugins/relay/relay-websocket.c in the Relay plugin.

Record
DEBIAN-CVE-2021-40516
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Updated
2026-11-02
OSVUBUNTU-CVE-2021-40516 7.5

WeeChat before 3.2.1 allows remote attackers to cause a denial of service (crash) via a crafted WebSocket frame that trigger an out-of-bounds read in plugins/relay/relay-websocket.c in the Relay plugin.

Record
UBUNTU-CVE-2021-40516
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Updated
2026-11-02
OSVMGASA-2021-0466 No score

Updated weechat packages fix security vulnerability

A crafted WebSocket frame could result in a crash in the weechat Relay plugin.

Record
MGASA-2021-0466
Updated
2026-11-02
OSVopenSUSE-SU-2022:0083-1 No score

Security update for weechat

This update for weechat fixes the following issues:

update to 3.2.1:

  • CVE-2021-40516: relay: fix crash when decoding a malformed websocket frame (boo#1190206)

update to 3.2

main changes:

  • use XDG directories by default (config, data, cache, runtime)
  • add support of IRC SASL mechanisms SCRAM-SHA-1, SCRAM-SHA-256 and SCRAM-SHA-512
  • automatically load system certificates without giving a hardcoded path to the file with certificates
  • add options to customize commands executed on system signals received (SIGHUP, SIGQUIT, SIGTERM, SIGUSR1, SIGUSR2)
  • add bar item 'tls_version' and buflist format
  • add signals 'cursor_start' and 'cursor_end'
  • add function crypto_hmac in API
  • add translated string in evaluation of expressions with 'translate:xxx'
  • add info 'weechat_daemon'
  • add Python stub for WeeChat API
  • add variables '${tg_shell_argc}' and '${tg_shell_argvN}' in command trigger evaluated strings
  • many bugs fixed.

for all changes, please visit: https://weechat.org/files/changelog/ChangeLog-3.2.html

update to 3.1

New features

  • core: add options weechat.look.hotlist_update_on_buffer_switch and weechat.look.read_marker_update_on_buffer_switch (issue #992, issue #993)
  • core: add option sec.crypt.passphrase_command to read passphrase from an external program on startup, remove option sec.crypt.passphrase_file (issue #141)
  • core: improve debug in command /eval: display more verbose debug with two '-d', add indentation and colors
  • core: add options 'setvar' and 'delvar' in command /buffer, rename option 'localvar' to 'listvar'
  • core: add buffer local variable 'completion_default_template' (evaluated) to override the value of option 'weechat.completion.default_template' (issue #1600)
  • core: add option 'recreate' in command /filter
  • core: add raw string in evaluation of expressions with 'raw:xxx' (issue #1611)
  • core: add evaluation of conditions in evaluation of expressions with 'eval_cond:xxx' (issue #1582)
  • api: add info_hashtable 'secured_data'
  • irc: add info 'irc_is_message_ignored'
  • irc: add server option 'default_chantypes', used when the server does not send them in message 005 (issue #1610)
  • trigger: add variable '${tg_trigger_name}' in command trigger evaluated strings (issue #1580)
  • Bug fixes

    • core: fix quoted line in cursor mode (issue #1602)
    • core: fix wrong size of the new window after vertical split (issue #1612)
    • core: do not remove quotes in arguments of command /eval as they can be part of the evaluated expression/condition (issue #1601)
    • core: display an error when the buffer is not found with command /command -buffer
    • buflist: add option buflist.look.use_items to speed up display of buflist (issue #1613)
    • irc: add bar item 'irc_nick_prefix'
    • irc: fix separator between nick and host in bar item 'irc_nick_host'
    • irc: fix completion of commands /halfop and /dehalfop
  • Documentation

    • do not build weechat-headless man page if headless binary is disabled (issue #1607)

update to 3.0.1:

  • exec: fix search of command by identifier
  • spell: fix refresh of bar item 'spell_suggest' when the input becomes empty (issue #1586)
  • spell: fix crash with IRC color codes in command line (issue #1589)

update to 3.0

New features

  • api: add optional list of colors in infos 'nick_color' and 'nick_color_name' (issue #1565)
  • api: add argument 'bytes' in function string_dyn_concat
  • api: add function string_color_code_size (issue #1547)
  • exec: add option '-oerr' to send stderr to buffer (now disabled by default) (issue #1566)
  • fset: add option fset.look.auto_refresh (issue #1553)
  • irc: add pointer to irc_nick in focus of bar item 'buffer_nicklist' (issue #1535, issue #1538)
  • irc: allow to send text on buffers with commands /allchan, /allpv and /allserv
  • irc: evaluate command executed by commands /allchan, /allpv and /allserv (issue #1536)
  • script: add…
Record
openSUSE-SU-2022:0083-1
Updated
2026-11-02
OSVUSN-5258-1 No score

weechat vulnerabilities

Stuart Nevans Locke discovered that WeeChat's relay plugin insecurely handled malformed websocket frames. A remote attacker in control of a server could possibly use this issue to cause denial of service in a client. (CVE-2021-40516)

Stuart Nevans Locke discovered that WeeChat insecurely handled certain IRC messages. A remote attacker in control of a server could possibly use this issue to cause denial of service in a client. This issue only affected Ubuntu 16.04 ESM and Ubuntu 18.04 ESM. (CVE-2020-9760)

Stuart Nevans Locke discovered that WeeChat insecurely handled certain IRC messages. A remote unauthenticated attacker could possibly use these issues to cause denial of service in a client. These issues only affected Ubuntu 16.04 ESM and Ubuntu 18.04 ESM. (CVE-2020-9759, CVE-2020-8955)

Joseph Bisch discovered that WeeChat's logger incorrectly handled certain memory operations when handling log file names. A remote attacker could possibly use this issue to cause denial of service in a client. This issue only affected Ubuntu 16.04 ESM. (CVE-2017-14727)

Record
USN-5258-1
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
weechat
Alpine:v3.15
0.4.1 up to 3.5-r0
3.5-r0
weechat
Debian:12
before 3.2.1-1
3.2.1-1
weechat
Debian:13
before 3.2.1-1
3.2.1-1
weechat
Debian:14
before 3.2.1-1
3.2.1-1
weechat
Debian:9
From an advisory covering 4 CVEs
before 1.6-1+deb9u3, plus listed versions
1.6-1+deb9u11.6-1+deb9u2
1.6-1+deb9u3
weechat
Mageia:8
before 3.0-1.1.mga8
3.0-1.1.mga8
weechat
Ubuntu:Pro:16.04:LTS
before 1.4-2ubuntu0.1+esm1, plus listed versions
1.3-11.3-1build11.4-11.4-1build11.4-1build21.4-21.4-2ubuntu0.1
1.4-2ubuntu0.1+esm1
weechat
Ubuntu:Pro:18.04:LTS
before 1.9.1-1ubuntu1+esm1, plus listed versions
1.9.1-11.9.1-1build11.9.1-1ubuntu1
1.9.1-1ubuntu1+esm1
weechat
Ubuntu:Pro:20.04:LTS
before 2.8-1ubuntu0.1~esm1, plus listed versions
2.6-22.6-2build12.6-2build22.6-2ubuntu12.6-2ubuntu22.8-1
2.8-1ubuntu0.1~esm1
weechat
Ubuntu:Pro:16.04:LTS
From an advisory covering 5 CVEs
before 1.4-2ubuntu0.1+esm1, plus listed versions
1.3-11.3-1build11.4-11.4-1build11.4-1build21.4-21.4-2ubuntu0.1
1.4-2ubuntu0.1+esm1
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Affected packages
PackageAffectedFixed
weechat
Ubuntu:Pro:18.04:LTS
From an advisory covering 5 CVEs
before 1.9.1-1ubuntu1+esm1, plus listed versions
1.9.1-11.9.1-1build11.9.1-1ubuntu1
1.9.1-1ubuntu1+esm1
weechat
Ubuntu:Pro:20.04:LTS
From an advisory covering 5 CVEs
before 2.8-1ubuntu0.1~esm1, plus listed versions
2.6-22.6-2build12.6-2build22.6-2ubuntu12.6-2ubuntu22.8-1
2.8-1ubuntu0.1~esm1
weechat
SUSE:Package Hub 15 SP3
before 3.2.1-bp153.2.3.1
3.2.1-bp153.2.3.1
weechat
openSUSE:Leap 15.3
before 3.2.1-bp153.2.3.1
3.2.1-bp153.2.3.1

History

History
RecordedChangedSources
affected, facts
affected, aliases, referencesOSV
aliasesEUVD
first indexedCVE List, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2021-40516 is a high vulnerability (CVSS 7.5) in Weechat, published September 5, 2021. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 1.59%, the 75th percentile. Fixed in weechat 3.5-r0.

References

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This page doesn't list everything

Left out here: the rest of 1 source description. The JSON record has them.

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