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

Quick assessment

Affected
bunkerity bunkerweb
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

BunkerWeb 是一款开源的下一代 Web 应用防火墙。在 1.6.13 版本之前， 、 以及 中的黑名单、灰名单和反机器人模块，在处理环境变量 、 和 中的 PTR 后缀匹配时存在信任缺陷：它们未通过 函数确认主机名确实解析到客户端的实际 IP 地址。这使得未认证的远程攻击者，若能控制某个 PTR 记录，即可伪造受信任的后缀，从而绕过基于反向 DNS（rDNS）的黑名单机制、使请求进入灰名单处理流程，或逃避反机器人挑战。该问题已在 1.6.13 版本中修复。

CVSS 5.9 · Medium EPSS 0.46% · P38

Affected Version Matrix 1

VendorProduct Version RangeStatus
bunkerity bunkerweb < 1.6.13 affected
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I. Basic Information for CVE-2026-75514

Vulnerability Information
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Vulnerability Title
BunkerWeb: rDNS bypass via missing forward-confirmation (FCrDNS) in blacklist, greylist, and antibot
Source: CVE Program / CVE List V5
Vulnerability 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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
不恰当地信任反向DNS
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
bunkerity bunkerweb < 1.6.13 -

II. Public POCs for CVE-2026-75514

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III. Intelligence Information for CVE-2026-75514

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Patches & Fixes for CVE-2026-75514 (1)

Vendor Advisories for CVE-2026-75514 (1)

Vendor Pages for CVE-2026-75514 (1)

IV. Related Vulnerabilities

Same product: bunkerweb
Same vendor: bunkerity
Same weakness: CWE-350

V. Comments for CVE-2026-75514

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