CVE-2025-2784

What it actually does

Heap buffer over-read of one byte in skip_insight_whitespace() during HTTP content sniffing, triggered by a crafted server response processed by libsoup clients.

Why it matters to the business

Applications relying on libsoup for HTTP requests face risk of crashes or limited information disclosure when connecting to untrusted servers, potentially affecting stability in GNOME-based desktop and server software after more than 500 days of exposure.

How an attack unfolds

An attacker hosts a malicious HTTP server that returns a specially crafted response; when a vulnerable libsoup client fetches content from it, the skip_insight_whitespace function performs an out-of-bounds read during content-type sniffing.

How to fix it

Update gnome/libsoup to the commit 766e17528251c9b696a6076300ac61adc95536ac or later; rebuild and redeploy dependent applications after the upgrade.

How to confirm the fix worked

Verify the installed libsoup source or package contains commit 766e17528251c9b696a6076300ac61adc95536ac; recompile and test clients against crafted responses to confirm absence of the over-read.

Typical attack path

1. Attacker deploys HTTP server returning crafted response bytes designed to trigger whitespace-skipping logic
2. Victim application using libsoup initiates an HTTP request to the attacker-controlled server
3. Server delivers the malicious response
4. libsoup processes the response and calls skip_insight_whitespace leading to one-byte over-read

How to detect it

Search application and system logs for unexpected crashes or segmentation faults originating from libsoup HTTP response handling; correlate with outbound connections to untrusted domains around the time of the fault.

What your security team should do

• Prioritize upgrade of all libsoup instances to the fixed commit within standard change windows
• Review and inventory applications that link against libsoup for HTTP client functionality
• Monitor upstream GNOME release notes for any additional backports or related fixes