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VulnerabilityPublished

CVE-2026-121763: Hummingbird (WordPress plugin) · Cross-site Scripting

Affects Hummingbird (WordPress plugin)Source CVE Database V5

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Not known to be exploited · CVSS 6.5 Medium : upgrade to 4.0.0 when convenient.

Data as of 9 Nov 2026, 10:35 UTC

CVSS 3.1 base score
6.5Medium
How severe the flaw is on the 0–10 CVSS scale.

Thin evidence

One scorer or none
CVSS scores by source
CNA (Patchstack)CVSS 3.16.5
Patch
Available – fixed in 4.0.0
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:L

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 9 Nov 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 8 Nov 2026.

What to do

Upgrade Hummingbird (WordPress plugin) to 4.0.0.

Affected software

ProductAffectedFixed in
Hummingbirdhummingbird-performanceAffected
  • <4.0.0
Fixed in
  • 4.0.0

AI-suggested

Upgrade to WPMU DEV Hummingbird version 4.0.0 or later, where this vulnerability is fixed. No other mitigation steps are indicated by the vendor advisory.

Description

CVE-2026-121763 is a stored cross-site scripting (XSS) vulnerability in WPMU DEV Hummingbird plugin versions before 4.0.0. The flaw allows improper neutralization of input during web page generation, potentially enabling attackers to inject malicious scripts. The vulnerability is fixed in version 4.0.0.

References

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