CVE-2025-4945

What it actually does

Integer overflow during expiration date arithmetic in libsoup cookie parsing routines allows crafted large integer values to trigger undefined behavior and bypass intended expiration validation.

Why it matters to the business

Applications relying on libsoup may retain cookies beyond their intended lifetime, potentially enabling unintended persistent state or tracking in GNOME-based and other Linux environments; the issue affects common Ubuntu server and cloud images with moderate urgency given the low EPSS and absence from KEV.

How an attack unfolds

An attacker supplies an HTTP response containing a cookie header with an oversized expiration value; when libsoup parses the date field the integer overflow occurs during arithmetic, resulting in the cookie being treated as non-expiring or exhibiting other unintended persistence.

How to fix it

Upgrade affected packages to the listed fixed versions: linux (Ubuntu 24.04 LTS) to 6.8.0-50.51, linux-aws (Ubuntu 24.04 LTS) to 6.8.0-1020.22, linux-azure (Ubuntu 24.04 LTS) to 6.8.0-1020.23; apply the corresponding kernel updates that include the corrected libsoup dependency handling.

How to confirm the fix worked

Verify installed package versions match or exceed the fixed releases above; recompile or run regression tests against cookie expiration parsing with boundary and oversized integer inputs; confirm no undefined behavior occurs in date arithmetic.

Typical attack path

1. Craft HTTP response or Set-Cookie header containing specially chosen large integer for expiration date
2. Deliver response to target application using libsoup for HTTP handling
3. Trigger cookie parsing path during normal request processing
4. Exploit integer overflow to alter expiration logic outcome
5. Observe or leverage resulting persistent cookie behavior

How to detect it

Inspect application and web server logs for unusual cookie header lengths or malformed date fields; correlate with processes using libsoup libraries; look for post-parsing artifacts indicating cookies persisting past expected TTLs in application state.

What your security team should do

• Prioritize patching Ubuntu 24.04 LTS systems running GNOME or libsoup-dependent services within standard maintenance windows
• Monitor upstream libsoup releases for any additional backports
• Review cookie handling code paths in custom applications for similar integer validation gaps