How severe is CVE-2020-8955?

CVE-2020-8955 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2020-8955 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 4% (88th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2020-8955?

CVE-2020-8955 primarily affects Weechat. In total, 9 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2020-8955?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.

When was CVE-2020-8955 published?

CVE-2020-8955 was published on 2020-02-12 and last updated on 2026-06-17.

CVE-2020-8955

CVE-2020-8955 is a critical-severity vulnerability in Weechat with a CVSS 3.x base score of 9.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-120.

Key facts

Severity: Critical (CVSS 3.x base score 9.8)
CVSS v2: 7.5
EPSS exploit prediction: 4% (88th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-120
Affected product: Weechat
Published: 2020-02-12
Last modified: 2026-06-17

Description

irc_mode_channel_update in plugins/irc/irc-mode.c in WeeChat through 2.7 allows remote attackers to cause a denial of service (buffer overflow and application crash) or possibly have unspecified other impact via a malformed IRC message 324 (channel mode).

Frequently asked questions

What is CVE-2020-8955?: irc_mode_channel_update in plugins/irc/irc-mode.c in WeeChat through 2.7 allows remote attackers to cause a denial of service (buffer overflow and application crash) or possibly have unspecified other impact via a malformed IRC message 324 (channel mode).
How severe is CVE-2020-8955?: CVE-2020-8955 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2020-8955 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 4% (88th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2020-8955?: CVE-2020-8955 primarily affects Weechat. In total, 9 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2020-8955?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
When was CVE-2020-8955 published?: CVE-2020-8955 was published on 2020-02-12 and last updated on 2026-06-17.

References

Affected products (9)

cpe:2.3:a:weechat:weechat:*:*:*:*:*:*:*:*
cpe:2.3:o:fedoraproject:fedora:30:*:*:*:*:*:*:*
cpe:2.3:o:fedoraproject:fedora:31:*:*:*:*:*:*:*
cpe:2.3:o:fedoraproject:fedora:32:*:*:*:*:*:*:*
cpe:2.3:a:opensuse:backports_sle:15.0:-:*:*:*:*:*:*
cpe:2.3:a:opensuse:backports_sle:15.0:sp1:*:*:*:*:*:*
cpe:2.3:o:opensuse:leap:15.1:*:*:*:*:*:*:*
cpe:2.3:o:debian:debian_linux:8.0:*:*:*:*:*:*:*
cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*

More vulnerabilities in Weechat

CVE-2024-46613 — Critical (CVSS 9.8): WeeChat before 4.4.2 has an integer overflow and resultant buffer overflow at core/core-string.c when there are more…
CVE-2020-9760 — Critical (CVSS 9.8): An issue was discovered in WeeChat before 2.7.1 (0.3.4 to 2.7 are affected). When a new IRC message 005 is received…
CVE-2021-40516 — High (CVSS 7.5): WeeChat before 3.2.1 allows remote attackers to cause a denial of service (crash) via a crafted WebSocket frame that…
CVE-2017-8073 — High (CVSS 7.5): WeeChat before 1.7.1 allows a remote crash by sending a filename via DCC to the IRC plugin. This occurs in the…
CVE-2022-28352 — Medium (CVSS 4.3): WeeChat (aka Wee Enhanced Environment for Chat) 3.2 to 3.4 before 3.4.1 does not properly verify the TLS certificate of…

All CVEs affecting Weechat →

Other CWE-120 (Classic Buffer Overflow) vulnerabilities

CVE-2025-48611 — Critical (CVSS 10.0): In DeviceId of DeviceId.java, there is a possible desync in persistence due to a missing bounds check. This could lead…
CVE-2026-24823 — Critical (CVSS 10.0): Out-of-bounds Write, Buffer Copy without Checking Size of Input ('Classic Buffer Overflow') vulnerability in FASTSHIFT…
CVE-2026-24810 — Critical (CVSS 10.0): Buffer Copy without Checking Size of Input ('Classic Buffer Overflow') vulnerability in rethinkdb (src/cjson modules).…
CVE-2026-24800 — Critical (CVSS 10.0): Out-of-bounds Write, Buffer Copy without Checking Size of Input ('Classic Buffer Overflow') vulnerability in tildearrow…
CVE-2025-9962 — Critical (CVSS 10.0): A buffer overflow vulnerability in Novakon P series allows attackers to gain root permission without prior…
CVE-2010-10016 — Critical (CVSS 10.0): BS.Player version 2.57 (build 1051) contains a vulnerability in its playlist import functionality. When processing .m3u…

Browse all CWE-120 (Classic Buffer Overflow) vulnerabilities →