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    1 vulnerability by umputun

    CVE-2026-48788 (GCVE-0-2026-48788)

    Vulnerability from cvelistv5 – Published: 2026-06-16 22:29 – Updated: 2026-06-17 13:20
    VLAI
    Title
    Remark42: Cross-Site Scripting (XSS) on /api/v1/img via content-type spoofing
    Summary
    Remark42 is a self-hosted comment engine for blogs, articles, or any other place where readers can add comments. Versions 1.6.0 through 1.15.0 contain a Cross-Site Scripting (XSS) vulnerability exploitable through content-type spoofing. The Remark42 image proxy fetches an arbitrary remote URL and re-serves the response from Remark42's own origin. During the download phase, the proxy determines whether the resource is an image by inspecting only the Content-Type header advertised by the remote server, never examining the actual bytes; during the serving phase, it instead derives the response Content-Type by sniffing those bytes with http.DetectContentType. An attacker can exploit this inconsistency by hosting a URL that advertises Content-Type: image/png while returning an HTML/JavaScript body: the download check accepts it as an image, the serving path sniffs the body and emits Content-Type: text/html, and the browser renders the attacker-controlled HTML/JavaScript as a document within Remark42's origin. Exploitation requires no Remark42 account on the target instance; the attacker only needs to host the malicious upstream URL and deliver the proxy link to a victim by any means, such as email, direct message, or a link on another website. This issue has been fixed in version 1.16.0.
    Severity
    8.2 (High)
    CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:L/A:N
    SSVC
    Exploitation: poc Automatable: no Technical Impact: partial
    CISA Coordinator (v2.0.3)
    CWE
    • CWE-79 - Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
    • CWE-436 - Interpretation Conflict
    Assigner
    References
    Impacted products
    Vendor Product Version
    umputun remark42 Affected: >= 1.6.0, < 1.16.0
    		Create a notification for this product.
    Show details on NVD website
    To clipboard 

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