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CVE-2026-55951— httpc memory exhaustion via unbounded response header accumulation

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是Erlang/OTP团队开源的一个JavaScript编写的处理处理异常的库。该库可以捕捉node.js内置API引发的异常。 Erlang/OTP 17.0至27.3.4.17之前版本、28.0至28.5.0.6之前版本和29.0至29.0.6之前版本存在资源管理错误漏洞，该漏洞源于httpc HTTP客户端未限制响应头总大小（max_header_size选项默认为无限制），导致客户端进程分配无界内存，可能造成系统内存耗尽或BEAM VM崩溃。

CVSS 8.2 · High EPSS 0.69% · P52

Possible ATT&CK Techniques 1 AI

T1298

Affected Version Matrix 9

VendorProduct Version RangeStatus
Erlang OTP < 17.0 unknown
17.0< 27.3.4.17 affected
28.0< 28.5.0.6 affected
29.0< 29.0.6 affected
< 5.10 unknown
5.10< 9.3.2.7 affected
9.4< 9.6.2.3 affected
9.7< 9.7.2 affected
… +1 more rows
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I. Basic Information for CVE-2026-55951

Vulnerability Information
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Vulnerability Title
httpc memory exhaustion via unbounded response header accumulation
Source: CVE Program / CVE List V5
Vulnerability Description
The Erlang/OTP httpc HTTP client does not enforce a limit on the total size of response headers received from a server. The max_header_size option defaults to nolimit, and httpc_response:parse_headers/6 accumulates every header into a list before the length check runs (which only fires after the terminating CRLF CRLF is received). A malicious or compromised HTTP server can send an arbitrarily large number of headers, or headers with very large values, causing the client process to allocate unbounded memory until the system runs out of memory or the BEAM VM crashes. A proof-of-concept server sending 100,000 headers of roughly 4000 bytes each caused the client VM to allocate over 13 GB of memory in under 30 seconds. Any application using httpc:request/4,5 to connect to untrusted servers is affected. No authentication is required: any server the client connects to (including via a redirect or man-in-the-middle) can trigger the exhaustion. 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:H/SC:N/SI:N/SA:N
Source: CVE Program / CVE List V5
Vulnerability Type
不加限制或调节的资源分配
Source: CVE Program / CVE List V5
Vulnerability Title
Erlang/OTP 资源管理错误漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Erlang/OTP是Erlang/OTP团队开源的一个JavaScript编写的处理处理异常的库。该库可以捕捉node.js内置API引发的异常。 Erlang/OTP 17.0至27.3.4.17之前版本、28.0至28.5.0.6之前版本和29.0至29.0.6之前版本存在资源管理错误漏洞，该漏洞源于httpc HTTP客户端未限制响应头总大小（max_header_size选项默认为无限制），导致客户端进程分配无界内存，可能造成系统内存耗尽或BEAM VM崩溃。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

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-2026-55951

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III. Intelligence Information for CVE-2026-55951

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Vendor Advisories for CVE-2026-55951 (2)

Other References for CVE-2026-55951 (1)

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-2026-75538 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-2026-73270 8.2 HIGH httpd mod_auth directory protection bypassed by request path casing on case-insensitive fi
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
Same vendor: Erlang
Same weakness: CWE-770