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CVE-2026-71562— httpc does not bound server-supplied numeric header values before integer conversion

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 中的 inets 组件的 httpc 模块存在一个“输入中指定数量验证不当”的漏洞。该漏洞允许恶意或已被攻陷的 HTTP 服务器通过返回一个包含极长数字串的数值型响应头，从而导致服务可用性降级。 具体技术细节如下： 1. 在 中， 使用 将服务器提供的 转换为整数，然后再与 进行比较。因此，大小检查无法保护转换过程，且 选项默认值为 。 2. 同样的无界转换也出现在 函数中对 的处理，以及 函数中对 的处理。后者仅通过检查首字符是否为数字来守卫。 3. 一个包含多达约 126 万位数字的值可以

CVSS 6.3 · Medium

Possible ATT&CK Techniques 1 AI

T1499 · Endpoint Denial of Service
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I. Basic Information for CVE-2026-71562

Vulnerability Information
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Vulnerability Title
httpc does not bound server-supplied numeric header values before integer conversion
Source: CVE Program / CVE List V5
Vulnerability Description
Improper Validation of Specified Quantity in Input vulnerability in Erlang/OTP inets httpc allows a malicious or compromised HTTP server to degrade availability by returning a numeric header whose value is a very long run of digits. httpc_handler.erl converts the server-supplied Content-Length with list_to_integer/1 before comparing it against max_body_size, so the size check cannot protect the conversion, and the option defaults to nolimit in any case. The same unbounded conversion appears in httpc_response:format_response/1 for Content-Length and in httpc_response:get_ms_from_retry_after/1 for Retry-After, which is guarded only by a check that the first character is a digit. A value of up to roughly 1.26 million digits converts successfully and costs the requesting process hundreds of milliseconds of arbitrary-precision arithmetic per response. The conversion function is documented to accept integers of any size, so bounding the input is the caller's responsibility. 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:N/VI:N/VA:L/SC:N/SI:N/SA:N
Source: CVE Program / CVE List V5
Vulnerability Type
CWE-1284
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
Erlang OTP 17.0 ~ 27.3.4.17 cpe:2.3:a:erlang:erlang\/otp:*:*:*:*:*:*:*:*
Erlang OTP 5.10 ~ 9.3.2.7 cpe:2.3:a:erlang:erlang\/otp:*:*:*:*:*:*:*:*
Erlang OTP 84adefa331c4159d432d22840663c38f155cd4c1 ~ * cpe:2.3:a:erlang:erlang\/otp:*:*:*:*:*:*:*:*

II. Public POCs for CVE-2026-71562

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III. Intelligence Information for CVE-2026-71562

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Other References for CVE-2026-71562 (3)

Same Patch Batch · Erlang · 2026-09-01 · 8 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-2026-66357 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-2026-59696 6.9 MEDIUM uri_string does not bound the port component of a URI before integer conversion

IV. Related Vulnerabilities

Same product: OTP
Same vendor: Erlang
Same weakness: CWE-1284

V. Comments for CVE-2026-71562

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