Cookie attribute injection via unescaped semicolons
Published Jul 10, 2026 · Updated Jul 10, 2026
Cookie attribute injection in elixir-plug Plug allows remote attackers to override Set-Cookie attributes through reflected input. Plug.Conn.Cookies.encode/2 interpolates cookie values and path, domain, same_site, and extra fields into the header without rejecting semicolons, which delimit attributes. Exploitation requires an application to place attacker-controlled data in a cookie field; it changes cookie scope or protections and enables cookie tossing or session fixation, but not response splitting.
Summary
What happened
Cookie attribute injection in elixir-plug Plug allows remote attackers to override Set-Cookie attributes through reflected input. Plug.Conn.Cookies.encode/2 interpolates cookie values and path, domain, same_site, and extra fields into the header without rejecting semicolons, which delimit attributes. Exploitation requires an application to place attacker-controlled data in a cookie field; it changes cookie scope or protections and enables cookie tossing or session fixation, but not response splitting.
The record
- CVE
- CVE-2026-56813
- Published
- Jul 10, 2026
- Updated
- Jul 10, 2026
- Vendor
- elixir-plug
- Product
- Plug
- Classifications
- CWE-141
- Attack vector
- local
- Privileges
- unauthenticated
Timeline
How it unfolded
- Jul 10, 2026CVE publishedPublication date reported by the CVE source.
- Jul 10, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
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- Affected versionversion=0.1.0 <1.16.6
- Affected versionversion=1.17.0 <1.17.4
- Affected versionversion=1.18.0 <1.18.5
- Affected versionversion=1.19.0 <1.19.5
- Affected versionversion=1.20.0 <1.20.3
- Affected versionversion=f26876aa67aaeb38e616638aa3efbcc2fe2906a5 <* changes=[{"at":"3f00dfad4e20ba88472e315c90a25742bf178f8e","status":"unaffected"},{"at":"a6d1248659022749869963fd302687165ecf8c8b","status":"unaffected"},{"at":"4167981747fe9ce75f374b94a28861ae950ea992","status":"unaffected"},{"at":"149d9ed68fee0b4f77efd1e835ce5d785856697b","status":"unaffected"},{"at":"eceb8315ce9a31ef784943a95a8624ebd1bc7e06","status":"unaffected"}]
What conditions does exploitation require?
What is affected?
Published CVSS scores
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Attacks
What attackers are doing with it
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Weakness, pattern, technique
Public exploit references
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Technologies
Your stack
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Your stack
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