CVE-2026-118656

Echo: Open Redirect via Control-Character Prefix Defeating sanitizeURI

Echo is a Go web framework. Prior to 4.16.0 and 5.4.0, sanitizeURI checks only the first two bytes of a redirect target before deciding whether it begins with an absolute-path separator pair. When AddTrailingSlash or RemoveTrailingSlash is configured with a redirect status, a slash, TAB, separator path form can evade the guard, be emitted in the Location header, and be normalized by a browser into an attacker-controlled host. This issue is fixed in 4.16.0 and 5.4.0.

Affected

labstack · echo

CVSS v3.1 GITHUB

6.1 MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

EPSS

0.20% chance of exploitation in the next 30 days, 9th percentile

Published

2026-10-28

Updated

2026-10-29

Proof-of-concept exploits (1)

• advisories/GHSA-v753-g4cw-jm48find archive

CVE references

• labstack/echo/commit/b838391e2eade87ae7e5a09d7bb5087bec271ec1REFERENCE
• labstack/echo/commit/fc410094b2f3415cf2bf5204082137b205bfd5afREFERENCE
• labstack/echo/releases/tag/v4.16.0REFERENCE
• labstack/echo/releases/tag/v5.4.0REFERENCE
• labstack/echo/security/advisories/GHSA-v753-g4cw-jm48REFERENCE

References

• CVE Record
• NVD entry