BunkerWeb: rDNS bypass via missing forward-confirmation (FCrDNS) in blacklist, greylist, and antibot

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-75514
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-08-20 19:17:03 UTC
Updated2026-08-20 19:17:03 UTC
DescriptionBunkerWeb is an open-source, next-generation Web Application Firewall. Prior to 1.6.13, the blacklist, greylist, and antibot modules in src/common/core/blacklist/blacklist.lua, src/common/core/greylist/greylist.lua, and src/common/core/antibot/antibot.lua trust PTR suffix matches in IGNORE_RDNS, GREYLIST_RDNS, and ANTIBOT_IGNORE_RDNS without using get_ips to confirm that the hostname resolves to the client address. An unauthenticated remote attacker who controls a PTR record can spoof a trusted suffix to bypass rDNS-based blacklisting, gain greylist treatment, or skip an antibot challenge. This issue is fixed in version 1.6.13.

Risk And Classification

Primary CVSS: v3.1 5.9 MEDIUM from [email protected]

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

Problem Types: CWE-350 | CWE-350 CWE-350: Reliance on Reverse DNS Resolution for a Security-Critical Action

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary5.9MEDIUMCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N
3.1CNADECLARED5.9MEDIUMCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
High
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
High
Availability
None

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

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Bunkerity Bunkerweb affected < 1.6.13 Not specified

References

ReferenceSourceLinkTags
github.com/bunkerity/bunkerweb/releases/tag/v1.6.13 [email protected] github.com
github.com/bunkerity/bunkerweb/security/advisories/GHSA-q54j-5484-pvjm 134c704f-9b21-4f2e-91b3-4a467353bcc0 github.com
github.com/bunkerity/bunkerweb/commit/1a97e5b3f977130a1b84507a9e1f703c8e... [email protected] github.com
github.com/bunkerity/bunkerweb/pull/3710 [email protected] github.com
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