What’s Vulnerable › Vulnerabilities

CVE-2026-75514: BunkerWeb: rDNS bypass via missing forward-confirmation (FCrDNS) in blacklist, greylist, and antibot

• Severity: medium (CVSS 5.9 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.6% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-08-20 · updated 2026-10-18
• Weakness: CWE-350

Description

BunkerWeb 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.

Affected products

• bunkerity bunkerweb: before 1.6.13

References

• https://github.com/bunkerity/bunkerweb/commit/1a97e5b3f977130a1b84507a9e1f703c8eec12eb
• https://github.com/bunkerity/bunkerweb/pull/3710
• https://github.com/bunkerity/bunkerweb/releases/tag/v1.6.13
• https://github.com/bunkerity/bunkerweb/security/advisories/GHSA-q54j-5484-pvjm
• https://github.com/bunkerity/bunkerweb/security/advisories/GHSA-q54j-5484-pvjm

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