HOMEVULNERABILITIESCVE-2021-21705
MEDIUM

CVE-2021-21705

CWE-20Published: October 4, 2021· Updated: Jun 17, 2026

5.3
CVSS v3.1

Official Description

In PHP versions 7.3.x below 7.3.29, 7.4.x below 7.4.21 and 8.0.x below 8.0.8, when using URL validation functionality via filter_var() function with FILTER_VALIDATE_URL parameter, an URL with invalid password field can be accepted as valid. This can lead to the code incorrectly parsing the URL and potentially leading to other security implications - like contacting a wrong server or making a wrong access decision.

NVD Source

Technical Analysis

CVE-2021-21705 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.

The vulnerability requires no privileges and no user interaction, making it a prime target for automated exploitation campaigns and worm-like propagation.

CVSS v3.1 Vector Breakdown

Exploitability
Attack VectorNetwork
Attack ComplexityLow
Privileges Req.None
User InteractionNone
ScopeUnchanged
Impact
ConfidentialityNone
IntegrityLow
AvailabilityNone
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

Affected Vendors & Products

netapp1 product(s)
clustered data ontap
Oracle1 product(s)
sd-wan aware
PHP1 product(s)
php
Source: NVD CPE · 3 total CPE entries

Exploit & PoC Resources

NO KNOWN EXPLOITNo public exploit confirmed at this time
Exploit-DB
Offensive Security exploit database
GitHub PoC Search
Community PoC repositories
Rapid7 / Metasploit
Metasploit module search
PacketStorm
Security advisories & exploits
NVD Detail
Official NIST entry
MITRE CVE
CVE Program entry
External links open in a new tab. Always verify in a controlled environment before use.

Official Patches & Advisories

PATCHhttps://bugs.php.net/bug.php?id=81122
PATCHhttps://www.oracle.com/security-alerts/cpujan2022.html
PATCHhttps://bugs.php.net/bug.php?id=81122
PATCHhttps://www.oracle.com/security-alerts/cpujan2022.html
ADVISORYhttps://security.gentoo.org/glsa/202209-20
ADVISORYhttps://security.netapp.com/advisory/ntap-20211029-0006/
ADVISORYhttps://security.gentoo.org/glsa/202209-20
ADVISORYhttps://security.netapp.com/advisory/ntap-20211029-0006/

All References (8)

→
https://bugs.php.net/bug.php?id=81122Exploit · Issue Tracking · Patch · Vendor Advisory
→
https://security.gentoo.org/glsa/202209-20Third Party Advisory
→
https://security.netapp.com/advisory/ntap-20211029-0006/Third Party Advisory
→
https://www.oracle.com/security-alerts/cpujan2022.htmlPatch · Vendor Advisory
→
https://bugs.php.net/bug.php?id=81122Exploit · Issue Tracking · Patch · Vendor Advisory
→
https://security.gentoo.org/glsa/202209-20Third Party Advisory
→
https://security.netapp.com/advisory/ntap-20211029-0006/Third Party Advisory
→
https://www.oracle.com/security-alerts/cpujan2022.htmlPatch · Vendor Advisory

Quick Facts

CVE IDCVE-2021-21705
CVSS Score5.3 / 10
SeverityMEDIUM
WeaknessCWE-20
CISA KEVNo
Affected3 vendor(s)
PublishedOct 4, 2021

Related CVEs (CWE-20)

CVE-2007-4915
10.0
CVE-2008-4329
10.0
CVE-2021-23279
10.0
CVE-2023-41917
10.0
CVE-2009-0545
10.0
CVE-2008-0457
10.0

Recommended Actions

  • →Apply vendor patches immediately
  • →Monitor CVE-2021-21705 in threat intel feeds
  • →Review IDS/IPS signatures for exploitation attempts
Data sourced from NVD (NIST), CISA KEV, and EPSS (FIRST). Analysis generated by CTIWatch. CVE data is provided under the NVD usage policy.
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