CVE-2026-74994

Erlang is a general-purpose programming language and runtime environment. Erlang has built-in support for concurrency, distribution and fault tolerance. Erlang is used in several large telecommunication systems from Ericsson.

Security Fix(es):

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.(CVE-2026-55951)

Improper Validation of Specified Quantity in Input vulnerability in Erlang/OTP stdlib allows a remote attacker to degrade availability by supplying a URI whose port component is a very long run of digits.

uri_string:get_port/1 passes the port substring to binary_to_integer/1 with no length bound, catching only error:badarg, so a syntactically valid port of up to roughly 1.26 million digits converts successfully and costs the calling process hundreds of milliseconds of arbitrary-precision arithmetic. The conversion is reached from every authority-parsing path in uri_string:parse/1, including the host, registered-name, and IPv4 and IPv6 forms. parse/1 is the documented interface for parsing URIs, so any application that parses an attacker-supplied URI is exposed without further configuration. 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 21.0 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 stdlib from 3.5 before 6.2.2.5, from 7.0 before 7.3.0.2, and from 8.0 before 8.0.4.(CVE-2026-59696)

httpd has never implemented obs-fold (RFC 2616 §2.2 / RFC 7230 §3.2.4 header continuation lines). Every CRLF followed by a non-CRLF octet unconditionally starts a new header. This missing feature became a security concern as the understanding of HTTP request smuggling attacks evolved.

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.(CVE-2026-66357)

Path Equivalence vulnerability in Erlang/OTP inets httpd allows a remote unauthenticated attacker to read files inside a mod_auth protected directory by prefixing the request path with an extra slash.

httpd_request:validate_uri/1 normalises the request URI with uri_string:normalize/1, which performs RFC 3986 dot-segment removal but does not collapse empty path segments, so a doubled slash survives. mod_alias:real_name/3 concatenates the document root with that URI, and mod_auth:secret_path/3 then decides whether the result lies inside a protected directory block by running the configured directory path as an unanchored…

Erlang is a general-purpose programming language and runtime environment. Erlang has built-in support for concurrency, distribution and fault tolerance. Erlang is used in several large telecommunication systems from Ericsson.

Security Fix(es):

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.(CVE-2026-55951)

Improper Validation of Specified Quantity in Input vulnerability in Erlang/OTP stdlib allows a remote attacker to degrade availability by supplying a URI whose port component is a very long run of digits.

uri_string:get_port/1 passes the port substring to binary_to_integer/1 with no length bound, catching only error:badarg, so a syntactically valid port of up to roughly 1.26 million digits converts successfully and costs the calling process hundreds of milliseconds of arbitrary-precision arithmetic. The conversion is reached from every authority-parsing path in uri_string:parse/1, including the host, registered-name, and IPv4 and IPv6 forms. parse/1 is the documented interface for parsing URIs, so any application that parses an attacker-supplied URI is exposed without further configuration. 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 21.0 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 stdlib from 3.5 before 6.2.2.5, from 7.0 before 7.3.0.2, and from 8.0 before 8.0.4.(CVE-2026-59696)

httpd has never implemented obs-fold (RFC 2616 §2.2 / RFC 7230 §3.2.4 header continuation lines). Every CRLF followed by a non-CRLF octet unconditionally starts a new header. This missing feature became a security concern as the understanding of HTTP request smuggling attacks evolved.

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.(CVE-2026-66357)

Path Equivalence vulnerability in Erlang/OTP inets httpd allows a remote unauthenticated attacker to read files inside a mod_auth protected directory by prefixing the request path with an extra slash.

httpd_request:validate_uri/1 normalises the request URI with uri_string:normalize/1, which performs RFC 3986 dot-segment removal but does not collapse empty path segments, so a doubled slash survives. mod_alias:real_name/3 concatenates the document root with that URI, and mod_auth:secret_path/3 then decides whether the result lies inside a protected directory block by running the configured directory path as an unanchored…

Erlang is a general-purpose programming language and runtime environment. Erlang has built-in support for concurrency, distribution and fault tolerance. Erlang is used in several large telecommunication systems from Ericsson.

Security Fix(es):

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.(CVE-2026-55951)

Improper Validation of Specified Quantity in Input vulnerability in Erlang/OTP stdlib allows a remote attacker to degrade availability by supplying a URI whose port component is a very long run of digits.

uri_string:get_port/1 passes the port substring to binary_to_integer/1 with no length bound, catching only error:badarg, so a syntactically valid port of up to roughly 1.26 million digits converts successfully and costs the calling process hundreds of milliseconds of arbitrary-precision arithmetic. The conversion is reached from every authority-parsing path in uri_string:parse/1, including the host, registered-name, and IPv4 and IPv6 forms. parse/1 is the documented interface for parsing URIs, so any application that parses an attacker-supplied URI is exposed without further configuration. 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 21.0 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 stdlib from 3.5 before 6.2.2.5, from 7.0 before 7.3.0.2, and from 8.0 before 8.0.4.(CVE-2026-59696)

httpd has never implemented obs-fold (RFC 2616 §2.2 / RFC 7230 §3.2.4 header continuation lines). Every CRLF followed by a non-CRLF octet unconditionally starts a new header. This missing feature became a security concern as the understanding of HTTP request smuggling attacks evolved.

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.(CVE-2026-66357)

Path Equivalence vulnerability in Erlang/OTP inets httpd allows a remote unauthenticated attacker to read files inside a mod_auth protected directory by prefixing the request path with an extra slash.

httpd_request:validate_uri/1 normalises the request URI with uri_string:normalize/1, which performs RFC 3986 dot-segment removal but does not collapse empty path segments, so a doubled slash survives. mod_alias:real_name/3 concatenates the document root with that URI, and mod_auth:secret_path/3 then decides whether the result lies inside a protected directory block by running the configured directory path as an unanchored…

The mod_auth module in OTP's inets httpd server, when configured with dets or mnesia authentication backends and multiple directory configuration blocks, collapses all directory blocks into a single shared user/group namespace. A user added to one protected directory is accepted as valid for all other protected directories on the same server instance. 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.

The mod_auth module in OTP's inets httpd server, when configured with dets or mnesia authentication backends and multiple directory configuration blocks, collapses all directory blocks into a single shared user/group namespace. A user added to one protected directory is accepted as valid for all other protected directories on the same server instance.

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.

Wander Nauta discovered that Erlang incorrectly handled absolute paths when extracting zip archives. An attacker could possibly use this issue to write arbitrary files outside of the intended directory. This issue only affected Ubuntu 16.04 LTS, Ubuntu 18.04 LTS, and Ubuntu 20.04 LTS. (CVE-2025-4748)

It was discovered that the Erlang SFTP server did not properly limit the size of packets. A remote attacker could possibly use this issue to cause Erlang to use excessive resources, leading to a denial of service. This issue only affected Ubuntu 14.04 LTS, Ubuntu 16.04 LTS, and Ubuntu 18.04 LTS. (CVE-2025-26618)

It was discovered that the Erlang SSH server did not properly limit the length of algorithm names in key exchange messages. A remote attacker could possibly use this issue to cause Erlang to use excessive resources, leading to a denial of service. This issue only affected Ubuntu 14.04 LTS, Ubuntu 16.04 LTS, and Ubuntu 18.04 LTS. (CVE-2025-30211)

It was discovered that the Erlang TFTP server incorrectly handled certain file paths. A remote attacker could possibly use this issue to access files outside of the intended directory. (CVE-2026-21620)

It was discovered that the Erlang SFTP server incorrectly validated paths against the configured root directory. An authenticated user could possibly use this issue to access files outside of the root directory. (CVE-2026-23942)

It was discovered that the Erlang SSH server enabled zlib compression by default and did not limit the size of decompressed data. A remote attacker could possibly use this issue to cause Erlang to use excessive resources, leading to a denial of service. (CVE-2026-23943)

It was discovered that the Erlang HTTP server incorrectly applied directory access controls to CGI scripts served via script aliases. A remote attacker could possibly use this issue to bypass authentication and access protected CGI scripts. (CVE-2026-28808)

It was discovered that the Erlang DNS resolver used predictable transaction IDs and did not randomize source ports. A remote attacker could possibly use this issue to perform DNS cache poisoning attacks. This issue only affected Ubuntu 22.04 LTS, Ubuntu 24.04 LTS, and Ubuntu 26.04 LTS. (CVE-2026-28810)

It was discovered that Erlang did not verify the signatures of designated OCSP responder certificates. A remote attacker could possibly use this issue to forge OCSP responses and bypass certificate revocation checks. This issue only affected Ubuntu 26.04 LTS. (CVE-2026-32144)

It was discovered that the Erlang SFTP server incorrectly handled file attribute changes on open file handles. An authenticated user could possibly use this issue to modify the attributes of files outside of the root directory. (CVE-2026-32147)

It was discovered that Erlang incorrectly allowed non-CA certificates to act as intermediate certificate issuers. A remote attacker could possibly use this issue to forge certificate chains. (CVE-2026-42789)

It was discovered that Erlang incorrectly handled DNS name constraints during hostname verification. A remote attacker could possibly use this issue to bypass certificate validation. This issue only affected Ubuntu 18.04 LTS, Ubuntu 20.04 LTS, Ubuntu 22.04 LTS, Ubuntu 24.04 LTS, and Ubuntu 26.04 LTS. (CVE-2026-42790)

It was discovered that Erlang did not check the validity period of OCSP responder certificates. A remote attacker could possibly use this issue to forge OCSP responses using an expired responder certificate. This issue only affected Ubuntu 26.04 LTS. (CVE-2026-42791)

It was discovered that Erlang incorrectly handled relative paths when extracting zip archives. An attacker could possibly use this issue to write arbitrary files outside of the intended directory. This issue only affected Ubuntu 18.04 LTS, Ubuntu 20.04 LTS, Ubuntu 22.04 LTS, Ubuntu 24.04 LTS, and Ubuntu 26.04 LTS. (CVE-2026-47078)

It was discovered that the Erlang SFTP server exposed absolute paths when reading symbolic links. An…