WordPress Hummingbird plugin <= 3.21.2 - Cross Site Scripting (XSS) vulnerability
- Exploited
- No known exploitation
- Fix
- No fix listed
- Who is exposed
- Not reported
- Last modified
- A 0-100 score for how much a CVE matters across the industry: exploitation, exposure, how widely the software is used, severity and whether a fix exists.What do these mean? →
- 15/100 · provisional
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
- Exploitation: none
- Automatable: no
- Technical impact: partial
Summary
The Hummingbird performance plugin for WordPress, made by WPMU DEV, has a stored cross-site scripting flaw that lets an attacker inject malicious scripts into web pages. An attacker can reach it remotely over the network with low-privilege login, but a user must take an action for the attack to work.
Written by anthropic/claude-haiku-5.5 from the sources below. Verify against them.
Read the original description
Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') vulnerability in WPMU DEV Hummingbird hummingbird-performance allows Stored XSS.This issue affects Hummingbird: from n/a through 3.21.2.
cve.now Index
- Exploitation0/40No signal
- Exposure3/25Reachable over the network · Unknown: No advisory context yet
- Reach?/20Unknown. No tracked technology or package matched
- Severity6.5/10CVSS 6.5
- No patch5/5No patch listed yet
What would change the score
- Would score about 70 if added to CISA KEV
- Would score about 65 if CISA's SSVC rates exploitation active
- Would score about 34 if advisories confirm default setups are exposed
Timeline
- CVE published
- First seen by cve.now
- CISA SSVC assessment
Exploitation: none · Automatable: no · Technical impact: partial
- Record last updated
Affected versions
- hummingbird-performance
through 3.21.2
Evidence 1
- Link
Corrections
None so far.
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Questions about CVE-2026-121763
Is CVE-2026-121763 being exploited?
It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.Source: cve.now feed data
Which versions are affected by CVE-2026-121763?
hummingbird-performance: through 3.21.2.Source: cve.now feed data