HOMEVULNERABILITIESCVE-2021-21265
HIGH

CVE-2021-21265

CWE-644Published: March 10, 2021· Updated: Jun 17, 2026

7.5
CVSS v3.1

Official Description

October is a free, open-source, self-hosted CMS platform based on the Laravel PHP Framework. In October before version 1.1.2, when running on poorly configured servers (i.e. the server routes any request, regardless of the HOST header to an October CMS instance) the potential exists for Host Header Poisoning attacks to succeed. This has been addressed in version 1.1.2 by adding a feature to allow a set of trusted hosts to be specified in the application. As a workaround one may set the configuration setting cms.linkPolicy to force.

NVD Source

Technical Analysis

CVE-2021-21265 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.

A successful exploit results in full integrity compromise (data manipulation), with a CVSS base score of 7.5.

CVSS v3.1 Vector Breakdown

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

Affected Vendors & Products

octobercms1 product(s)
october
Source: NVD CPE · 1 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://github.com/octobercms/library/commit/f86fcbcd066d6f8b939e8fe897409d152b11c3c6
PATCHhttps://github.com/octobercms/october/commit/f638d3f78cfe91d7f6658820f9d5e424306a3db0
PATCHhttps://github.com/octobercms/october/security/advisories/GHSA-xhfx-hgmf-v6vp
PATCHhttps://github.com/octobercms/library/commit/f86fcbcd066d6f8b939e8fe897409d152b11c3c6
PATCHhttps://github.com/octobercms/october/commit/f638d3f78cfe91d7f6658820f9d5e424306a3db0
PATCHhttps://github.com/octobercms/october/security/advisories/GHSA-xhfx-hgmf-v6vp

All References (9)

→
https://github.com/octobercms/library/commit/f29865ae3db7a03be7c49294cd93980ec457f10d
→
https://github.com/octobercms/library/commit/f86fcbcd066d6f8b939e8fe897409d152b11c3c6Patch · Third Party Advisory
→
https://github.com/octobercms/october/commit/555ab61f2313f45d7d5d138656420ead536c5d30
→
https://github.com/octobercms/october/commit/f638d3f78cfe91d7f6658820f9d5e424306a3db0Patch · Third Party Advisory
→
https://github.com/octobercms/october/security/advisories/GHSA-xhfx-hgmf-v6vpPatch · Third Party Advisory
→
https://packagist.org/packages/october/backend
→
https://github.com/octobercms/library/commit/f86fcbcd066d6f8b939e8fe897409d152b11c3c6Patch · Third Party Advisory
→
https://github.com/octobercms/october/commit/f638d3f78cfe91d7f6658820f9d5e424306a3db0Patch · Third Party Advisory
→
https://github.com/octobercms/october/security/advisories/GHSA-xhfx-hgmf-v6vpPatch · Third Party Advisory

Quick Facts

CVE IDCVE-2021-21265
CVSS Score7.5 / 10
SeverityHIGH
WeaknessCWE-644
CISA KEVNo
Affected1 vendor(s)
PublishedMar 10, 2021

Related CVEs (CWE-644)

CVE-2023-47143
9.8
CVE-2024-39736
9.8
CVE-2026-33805
9.0
CVE-2023-32465
8.8
CVE-2017-6031
8.8
CVE-2020-6982
8.8

Recommended Actions

  • →Apply vendor patches immediately
  • →Monitor CVE-2021-21265 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.COM. CVE data is provided under the NVD usage policy.
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