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CVE PROGRAM SOURCE RECORD2.1 Low

CVE-2026-56813

Cookie attribute injection in Plug.Conn.Cookies.encode/2

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Status
Published
Published
Updated
Assigning organization
EEF

Description

Improper Neutralization of Parameter/Argument Delimiters vulnerability in elixir-plug plug allows an attacker to inject or override HTTP cookie attributes. The Plug.Conn.Cookies.encode/2 function in lib/plug/conn/cookies.ex builds the Set-Cookie response header by interpolating the cookie value and its path, domain, same_site, and extra attributes directly into the header without neutralizing the ; delimiter that separates cookie attributes. An application that places attacker-controlled data into a cookie value or attribute (for example via Plug.Conn.put_resp_cookie/4 when reflecting a username or preference) lets an attacker inject a ; to append or override cookie attributes (such as Domain and Path scope, or dropping the Secure and HttpOnly flags), enabling cookie tossing and session fixation. Carriage return, line feed, and null bytes are rejected by Plug.Conn header validation, so HTTP response splitting is not possible, but attribute injection through ; is not prevented. This issue affects plug: from 0.1.0 before 1.16.6, from 1.17.0 before 1.17.4, from 1.18.0 before 1.18.5, from 1.19.1 before 1.19.5, and from 1.20.0 before 1.20.3.

Affected products

Version statuses are supplied by the assigning organization. Consult the original record for detailed ranges and platform conditions.

elixir-plug plug

Default version status: unaffected

  • 0.1.0 to < 1.16.6affected
  • 1.17.0 to < 1.17.4affected
  • 1.18.0 to < 1.18.5affected
  • 1.19.1 to < 1.19.5affected
  • 1.20.0 to < 1.20.3affected
pkg:hex/plug

elixir-plug plug

Default version status: unaffected

  • f26876aa67aaeb38e616638aa3efbcc2fe2906a5 to < *affected
pkg:github/elixir-plug/plug

References