CVE-2026-66337 Libsoup: libsoup: heap buffer over-read via integer underflow in soup_filter_input_stream_read_until()
A malicious HTTP server can trigger a heap buffer over-read in libsoup via integer underflow, causing client crashes or memory disclosure.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-66337?
CVE-2026-66337 is a medium-severity vulnerability in Redhat Enterprise Linux, published on 24 Jul 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
A flaw was found in libsoup. An unsigned integer underflow in the soup_filter_input_stream_read_until() function causes a heap buffer over-read when parsing multipart HTTP responses. A malicious HTTP server can exploit this by sending a crafted multipart response, potentially causing the client application to crash or disclose sensitive heap memory.
Weakness: CWE-125
Which versions are affected by CVE-2026-66337?
It affects 2 products.
Products include Gnome Libsoup, Redhat Enterprise Linux.
How do I fix CVE-2026-66337?
Apply the vendor's patch.
Is CVE-2026-66337 being exploited?
There is no known exploitation of CVE-2026-66337 in the wild and no public exploit code.
Other vulnerabilities in Redhat Enterprise Linux
- CVE-2026-102556 Libsoup: libsoup: heap buffer overflow from websocket pong signal type confusion
- CVE-2026-102557 Libsoup: libsoup: heap buffer overflow during websocket message reassembly
- CVE-2026-102558 Libsoup: libsoup: heap buffer overflow during websocket receive-buffer growth
- CVE-2026-102559 Libsoup: libsoup: heap buffer overflow during websocket client-frame masking
- CVE-2026-102560 Libsoup: libsoup: heap buffer overflow during outgoing permessage-deflate buffer growth
Sources
Also known as AZL-94101, DEBIAN-CVE-2026-66337, ECHO-6567-18db-6979, GHSA-ww4c-c3rv-f96h, UBUNTU-CVE-2026-66337.