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CVE-2021-40516

25
FAUCET Score

CVE-2021-40516 is an out-of-bounds read vulnerability in WeeChat before version 3.2.1, specifically affecting the Relay plugin when processing crafted WebSocket frames. This flaw, rated High severity with a CVSS score of 7.5, allows unauthenticated remote attackers to cause a denial of service by crashing the application. There is currently no evidence of active exploitation, public exploit code, or significant community discussion surrounding this vulnerability.

Impacted Technologies

VendorProductVersion(s)CPE
>= 0.4.1, < 3.2.1CPE matchmatch criteria
cpe:2.3:a:weechat:weechat:*:*:*:*:*:*:*:*
10.0CPE matchmatch criteria
cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

7.5HIGH

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
NONE
Integrity Impact
NONE
Availability Impact
HIGH
Exploitability Score
3.9
Impact Score
3.6
CvssVersion
3.1

Exploit Intelligence

EPSS Score
1.59%
Probability of exploitation in next 30 days
EPSS Percentile
73.2%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0159 is in the 55th percentile among its peer group of 51,551 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.1 Mastodon, and 0.4 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (1)

github_advisorypatch availablevia nvd_reference
View patch

References

github.com / weechat/weechat/commit/8b1331f98de1714bae15a9ca2e2b393ba49d735b
PatchThird Party Advisory
lists.debian.org / debian-lts-announce/2021/09/msg00018.html
Mailing ListThird Party Advisory
weechat.org / doc/security
PatchVendor Advisory