Cyber Posture

CVE-2025-27088

HighPublic PoC

Published: 20 February 2025

Published
20 February 2025
Modified
20 May 2025
KEV Added
Patch
CVSS Score 8.2 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:L/A:N
EPSS Score 0.0049 65.8th percentile
Risk Priority 17 60% EPSS · 20% KEV · 20% CVSS

Description

Adversaries may take advantage of security vulnerabilities and inherent functionality in browser software to change content, modify user-behaviors, and intercept information as part of various browser session hijacking techniques.

Security Summary

CVE-2025-27088 is a Reflected Cross-site Scripting (XSS) vulnerability, classified under CWE-79, in oxyno-zeta/s3-proxy, an AWS S3 proxy implemented in Go. The flaw resides in the folder-list template, where the `Request.URL.Path` variable is directly rendered into HTML without sanitization or escaping, enabling injection of arbitrary HTML elements, including scripts, in affected versions prior to the fix.

Attackers without privileges (PR:N) can exploit this over the network (AV:N) by crafting malicious URLs embedding JavaScript or HTML payloads. Exploitation requires a user interaction (UI:R), such as visiting the URL, which triggers execution of the injected script in the victim's browser context on the trusted domain. This can facilitate session hijacking or phishing attacks, with a CVSS v3.1 base score of 8.2 (AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:L/A:N) indicating high confidentiality impact due to changed scope.

The GitHub security advisory (GHSA-pp9m-qf39-hxjc) confirms the issue was fixed in version 4.18.1 via commit c611c741ed4872ea3f46232be23bb830f96f9564, which addresses the vulnerable rendering in the folder-list.tpl template at lines 19:21-19:38. Users are advised to upgrade immediately, as no workarounds are available.

Details

CWE(s)
CWE-79

Affected Products

oxyno-zeta
s3-proxy
≤ 2.23.1 · ≤ 4.18.1 · ≤ 4.18.1

MITRE ATT&CK Enterprise Techniques

T1190 Exploit Public-Facing Application Initial Access
Adversaries may attempt to exploit a weakness in an Internet-facing host or system to initially access a network.
T1185 Browser Session Hijacking Collection
Adversaries may take advantage of security vulnerabilities and inherent functionality in browser software to change content, modify user-behaviors, and intercept information as part of various browser session hijacking techniques.
Why these techniques?

Reflected XSS in public-facing S3 proxy (T1190) allows unsanitized URL path rendering for script injection; directly facilitates browser session hijacking (T1185) via execution in trusted domain context leading to potential cookie/token theft.

Confidence: MEDIUM · MITRE ATT&CK Enterprise v19.0

References