CVE-2026-73270— httpd mod_auth directory protection bypassed by request path casing on case-insensitive filesystems
Quick assessment
Affected
Erlang OTP
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.
Erlang/OTP 的 inets 模块中的 httpd 存在大小写处理不当漏洞。在文件系统为大小写不敏感的部署环境中，未经身份验证的远程攻击者可以通过使用不同的大小写形式请求文件，从而读取位于 受保护目录内的文件。 函数在判断解析后的文件系统路径是否位于受保护的目录块内部时，使用 对配置的目录路径进行正则匹配，但未启用“忽略大小写”选项。因此，当请求路径为 ，而配置的受保护目录为 时，两者因大小写不同而无法匹配，系统将该请求视为未受保护，不再发出身份验证挑战（authentication challenge）。
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I. Basic Information for CVE-2026-73270
Vulnerability Information
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Vulnerability Title
httpd mod_auth directory protection bypassed by request path casing on case-insensitive filesystems
Source: CVE Program / CVE List V5
Vulnerability Description
Improper Handling of Case Sensitivity vulnerability in Erlang/OTP inets httpd allows a remote unauthenticated attacker to read files inside a mod_auth protected directory by requesting them with different casing, on deployments whose filesystem is case-insensitive.
mod_auth:secret_path/3 decides whether a resolved filesystem path lies inside a protected directory block by running the configured directory path through re:run/3 without the caseless option. A request for /secret/file against a directory configured as /Secret therefore does not match, so the request is treated as unprotected and no authentication challenge is issued, while the filesystem resolves the differently cased path to the same file and mod_get serves it. Deployments on case-sensitive filesystems are unaffected, because there the filesystem itself rejects the mismatched casing.
This issue affects OTP from OTP 17.0 before OTP 27.3.4.17, from OTP 28.0 before OTP 28.5.0.6, and from OTP 29.0 before OTP 29.0.6, corresponding to inets from 5.10 before 9.3.2.7, from 9.4 before 9.6.2.3, and from 9.7 before 9.7.2. Whether OTP before OTP 17.0, corresponding to inets before 5.10, is affected is unknown.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N
Source: CVE Program / CVE List V5
Vulnerability Type
大小写敏感处理不恰当
Source: CVE Program / CVE List V5
Affected Products
II. Public POCs for CVE-2026-73270
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Other References for CVE-2026-73270 (6)
Same Patch Batch · Erlang · 2026-09-01 · 16 CVEs total
| CVE-2026-71380 | 8.7 HIGH | httpd applies no timeout while receiving a request body, parking a worker on a stalled cli |
| CVE-2026-70399 | 8.7 HIGH | httpd does not enforce the documented default max_clients connection limit |
| CVE-2026-74835 | 8.7 HIGH | inets,httpd: Memory Exhaustion via Unenforced max_body_size During Chunked Body Reception |
| CVE-2026-69664 | 8.7 HIGH | httpd parks a request worker indefinitely on a malformed chunk size sent after the headers |
| CVE-2026-66357 | 8.3 HIGH | inets,httpd:HTTP Request Smuggling via obs-fold Header Continuation |
| CVE-2026-73812 | 8.3 HIGH | inets, httpd: HTTP Request Smuggling via Transfer-Encoding and Content-Length |
| CVE-2026-73276 | 8.3 HIGH | inets, httpd: HTTP Request Smuggling via Whitespace-Before-Colon Header Dropping i |
| CVE-2026-55951 | 8.2 HIGH | httpc memory exhaustion via unbounded response header accumulation |
| CVE-2026-75538 | 8.2 HIGH | A Signed Length Overflow in Erlang/OTP's inet TCP Driver Overflows the Receive Buffer Into |
| CVE-2026-66835 | 8.2 HIGH | httpd mod_auth directory protection bypassed by a doubled slash in the request path |
| CVE-2026-59696 | 6.9 MEDIUM | uri_string does not bound the port component of a URI before integer conversion |
| CVE-2026-71562 | 6.3 MEDIUM | httpc does not bound server-supplied numeric header values before integer conversion |
| CVE-2026-70405 | 6.3 MEDIUM | snmp BER INTEGER decoder applies no size limit to attacker-supplied integer fields |
| CVE-2026-70409 | 6.3 MEDIUM | eldap does not bound the port component of a referral URL before integer conversion |
| CVE-2026-74994 | 6.0 MEDIUM | inets, httpd: Authentication Bypass via Directory Namespace Collapse in httpd mod_auth |
IV. Related Vulnerabilities
Same product: OTP
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CVE-2026-69664
httpd parks a request worker indefinitely on a malformed chu -
CVE-2026-70409
eldap does not bound the port component of a referral URL be -
CVE-2026-70405
snmp BER INTEGER decoder applies no size limit to attacker-s -
CVE-2026-66835
httpd mod_auth directory protection bypassed by a doubled sl -
CVE-2026-75538
A Signed Length Overflow in Erlang/OTP's inet TCP Driver Ove
Same vendor: Erlang
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httpd parks a request worker indefinitely on a malformed chu -
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eldap does not bound the port component of a referral URL be -
CVE-2026-70405
snmp BER INTEGER decoder applies no size limit to attacker-s -
CVE-2026-66835
httpd mod_auth directory protection bypassed by a doubled sl -
CVE-2026-75538
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Same weakness: CWE-178
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V. Comments for CVE-2026-73270
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