CVE-2026-66337
Libsoup: libsoup: heap buffer over-read via integer underflow in soup_filter_input_stream_read_until()
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.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- None
- User interaction
- None
What an attacker can affect
- Confidentiality
- Low
- Integrity
- None
- Availability
- Low
Exploit likelihood
What each source reports
CVE List Score used
6.5
Libsoup: libsoup: heap buffer over-read via integer underflow in soup_filter_input_stream_read_until()
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.
- Record
CVE-2026-66337- CVSS 3.1
- 6.5 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:L - Weakness
- CWE-125
- Updated
- 2026-11-05
EUVDEUVD-2026-48753
6.5
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.
- Record
EUVD-2026-48753- CVSS 3.1
- 6.5 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:L - Updated
- 2026-11-05
GitHub AdvisoriesGHSA-ww4c-c3rv-f96h
6.5
A flaw was found in libsoup. An unsigned integer underflow in the...
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.
- Record
GHSA-ww4c-c3rv-f96h- CVSS 3.1
- 6.5 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:L - Weakness
- CWE-125
- Updated
- 2026-11-02
NVD
6.5
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.
- Record
CVE-2026-66337- CVSS 3.1
- 6.5 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:L - Weakness
- CWE-125
- Updated
- 2026-11-06
OSVDEBIAN-CVE-2026-66337
6.5
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.
- Record
DEBIAN-CVE-2026-66337- CVSS 3.1
- 6.5 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:L - Updated
- 2026-11-02
OSVOESA-2026-4389
6.5
libsoup security update
libsoup is an HTTP client/server library for GNOME. It uses GObjects and the glib main loop, to integrate well with GNOME applications, and also has a synchronous API, for use in threaded applications.
Security Fix(es):
SoupAuthManager caches proxy authentication credentials without scoping them to the proxy authority (host:port). When the proxy configuration changes (e.g., via system settings or WPAD), cached Proxy-Authorization headers from the previous proxy are sent to the new proxy, leaking credentials.(CVE-2026-12547)
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.(CVE-2026-66337)
- Record
OESA-2026-4389- CVSS 3.1
- 6.5 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:L - Updated
- 2026-11-02
Show 6 moreShow less
OSVOESA-2026-4390
6.5
libsoup security update
libsoup is an HTTP client/server library for GNOME. It uses GObjects and the glib main loop, to integrate well with GNOME applications, and also has a synchronous API, for use in threaded applications.
Security Fix(es):
SoupAuthManager caches proxy authentication credentials without scoping them to the proxy authority (host:port). When the proxy configuration changes (e.g., via system settings or WPAD), cached Proxy-Authorization headers from the previous proxy are sent to the new proxy, leaking credentials.(CVE-2026-12547)
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.(CVE-2026-66337)
- Record
OESA-2026-4390- CVSS 3.1
- 6.5 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:L - Updated
- 2026-11-02
OSVOESA-2026-4391
6.5
libsoup security update
libsoup is an HTTP client/server library for GNOME. It uses GObjects and the glib main loop, to integrate well with GNOME applications, and also has a synchronous API, for use in threaded applications.
Security Fix(es):
SoupAuthManager caches proxy authentication credentials without scoping them to the proxy authority (host:port). When the proxy configuration changes (e.g., via system settings or WPAD), cached Proxy-Authorization headers from the previous proxy are sent to the new proxy, leaking credentials.(CVE-2026-12547)
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.(CVE-2026-66337)
A flaw was found in libsoup. The chunked transfer encoding parser uses a permissive parsing function for chunk sizes that silently accepts inputs violating RFC 9112, including leading whitespace, plus sign prefixes, and trailing invalid characters. When libsoup operates behind a strict frontend proxy, this parsing differential can be exploited to smuggle HTTP requests.(CVE-2026-66338)
- Record
OESA-2026-4391- CVSS 3.1
- 6.5 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:L - Updated
- 2026-11-02
OSVOESA-2026-4441
8.6
libsoup security update
libsoup is an HTTP client/server library for GNOME. It uses GObjects and the glib main loop, to integrate well with GNOME applications, and also has a synchronous API, for use in threaded applications.
Security Fix(es):
A flaw was found in libsoup. When max-incoming-payload-size is unlimited (0), SoupWebsocketConnection could grow its incoming GByteArray based on an attacker-controlled frame length until the length wrapped, causing a heap buffer overflow while reading frame data.(CVE-2026-102558)
A flaw was found in libsoup. When the permessage-deflate WebSocket extension compresses a very large outgoing message, truncated size calculations used for GByteArray growth could wrap, causing zlib to write past the allocated buffer and resulting in a heap buffer overflow.(CVE-2026-102560)
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.(CVE-2026-66337)
- Record
OESA-2026-4441- CVSS 3.1
- 8.6 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:H - Updated
- 2026-11-02
OSVUBUNTU-CVE-2026-66337
6.5
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.
- Record
UBUNTU-CVE-2026-66337- CVSS 3.1
- 6.5 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:L - Updated
- 2026-11-03
OSVAZL-94101 No score
CVE-2026-66337 affecting package libsoup 3.4.4-18
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.
- Record
AZL-94101- Updated
- 2026-11-05
OSVopenSUSE-SU-2026:12365-1 No score
libsoup-3_0-0-3.8.1-1.1 on GA media
These are all security issues fixed in the libsoup-3_0-0-3.8.1-1.1 package on the GA media of openSUSE Tumbleweed.
- Record
openSUSE-SU-2026:12365-1- Updated
- 2026-11-02
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
libsoupAzure Linux:3 |
through 3.4.4-18 | None known |
libsoup2.4Debian:12 |
All versions, plus listed versions 2.74.3-12.74.3-1+deb12u12.74.3-102.74.3-10.12.74.3-11 Show 11 moreShow less2.74.3-22.74.3-32.74.3-3.1~exp12.74.3-3.1~exp22.74.3-3.1~exp32.74.3-52.74.3-62.74.3-72.74.3-82.74.3-8.12.74.3-9 |
None known |
libsoup2.4Debian:13 |
All versions, plus listed versions 2.74.3-10.12.74.3-11 |
None known |
libsoup3Debian:12 |
All versions, plus listed versions 3.2.2-23.2.3-0+deb12u13.2.3-0+deb12u23.3.1-13.4.0-1 Show 33 moreShow less3.4.1-13.4.2-13.4.2-23.4.2-33.4.2-43.4.3-13.4.4-13.4.4-23.4.4-33.4.4-43.4.4-53.5.2-13.6.0-13.6.0-23.6.0-33.6.0-43.6.1-13.6.4-13.6.4-23.6.4-33.6.5-13.6.5-23.6.5-33.6.5-43.6.5-53.6.5-63.6.5-73.6.5-83.6.5-93.6.6-13.8.0-13.8.0-23.8.0-3 |
None known |
libsoup3Debian:13 |
All versions, plus listed versions 3.6.5-33.6.5-43.6.5-53.6.5-63.6.5-7 Show 6 moreShow less3.6.5-83.6.5-93.6.6-13.8.0-13.8.0-23.8.0-3 |
None known |
libsoupopenEuler:24.03-LTS-SP1 From an advisory covering 2 CVEs |
before 2.74.3-29.oe2403sp1 | 2.74.3-29.oe2403sp1 |
libsoupopenEuler:24.03-LTS-SP3 From an advisory covering 2 CVEs |
before 2.74.3-29.oe2403sp3 | 2.74.3-29.oe2403sp3 |
libsoupopenEuler:24.03-LTS-SP4 From an advisory covering 3 CVEs |
before 2.74.3-29.oe2403sp4 | 2.74.3-29.oe2403sp4 |
libsoupopenEuler:22.03-LTS-SP4 From an advisory covering 3 CVEs |
before 2.74.2-27.oe2203sp4 | 2.74.2-27.oe2203sp4 |
libsoup2.4Ubuntu:Pro:16.04:LTS |
All versions, plus listed versions 2.50.0-2debian12.52.1-12.52.2-12.52.2-1ubuntu0.12.52.2-1ubuntu0.2 Show 10 moreShow less2.52.2-1ubuntu0.32.52.2-1ubuntu0.3+esm12.52.2-1ubuntu0.3+esm22.52.2-1ubuntu0.3+esm32.52.2-1ubuntu0.3+esm42.52.2-1ubuntu0.3+esm52.52.2-1ubuntu0.3+esm62.52.2-1ubuntu0.3+esm72.52.2-1ubuntu0.3+esm82.52.2-1ubuntu0.3+esm9 |
None known |
Show 11 moreShow less
| Package | Affected | Fixed |
|---|---|---|
libsoup2.4Ubuntu:Pro:18.04:LTS |
All versions, plus listed versions 2.60.1-12.60.2-12.60.2-22.60.3-12.61.90-1 Show 15 moreShow less2.62.0-12.62.1-12.62.1-1ubuntu0.12.62.1-1ubuntu0.32.62.1-1ubuntu0.42.62.1-1ubuntu0.4+esm12.62.1-1ubuntu0.4+esm22.62.1-1ubuntu0.4+esm32.62.1-1ubuntu0.4+esm42.62.1-1ubuntu0.4+esm52.62.1-1ubuntu0.4+esm62.62.1-1ubuntu0.4+esm72.62.1-1ubuntu0.4+esm82.62.1-1ubuntu0.4+esm92.62.1-1ubuntu0.4+esm10 |
None known |
libsoup2.4Ubuntu:Pro:20.04:LTS |
All versions, plus listed versions 2.68.2-0ubuntu12.68.2-12.68.2-22.68.2-2build22.69.90-1 Show 11 moreShow less2.70.0-12.70.0-1ubuntu0.12.70.0-1ubuntu0.22.70.0-1ubuntu0.32.70.0-1ubuntu0.42.70.0-1ubuntu0.52.70.0-1ubuntu0.5+esm12.70.0-1ubuntu0.5+esm22.70.0-1ubuntu0.5+esm32.70.0-1ubuntu0.5+esm42.70.0-1ubuntu0.5+esm5 |
None known |
libsoup2.4Ubuntu:22.04:LTS |
All versions, plus listed versions 2.72.0-3ubuntu32.74.1-12.74.2-22.74.2-32.74.2-3ubuntu0.1 Show 9 moreShow less2.74.2-3ubuntu0.22.74.2-3ubuntu0.32.74.2-3ubuntu0.42.74.2-3ubuntu0.52.74.2-3ubuntu0.62.74.2-3ubuntu0.72.74.2-3ubuntu0.82.74.2-3ubuntu0.92.74.2-3ubuntu0.10 |
None known |
libsoup3Ubuntu:Pro:22.04:LTS |
All versions, plus listed versions 3.0.4-23.0.4-33.0.5-13.0.7-0ubuntu13.0.7-0ubuntu1+esm1 Show 9 moreShow less3.0.7-0ubuntu1+esm23.0.7-0ubuntu1+esm33.0.7-0ubuntu1+esm43.0.7-0ubuntu1+esm53.0.7-0ubuntu1+esm63.0.7-0ubuntu1+esm73.0.7-0ubuntu1+esm83.0.7-0ubuntu1+esm93.0.7-0ubuntu1+esm10 |
None known |
libsoup2.4Ubuntu:24.04:LTS |
All versions, plus listed versions 2.74.3-12.74.3-22.74.3-32.74.3-62.74.3-6build1 Show 11 moreShow less2.74.3-6ubuntu12.74.3-6ubuntu1.12.74.3-6ubuntu1.22.74.3-6ubuntu1.32.74.3-6ubuntu1.42.74.3-6ubuntu1.52.74.3-6ubuntu1.62.74.3-6ubuntu1.72.74.3-6ubuntu1.82.74.3-6ubuntu1.92.74.3-6ubuntu1.10 |
None known |
libsoup3Ubuntu:24.04:LTS |
All versions, plus listed versions 3.4.2-43.4.4-13.4.4-23.4.4-43.4.4-5 Show 12 moreShow less3.4.4-5build13.4.4-5build23.4.4-5ubuntu0.13.4.4-5ubuntu0.23.4.4-5ubuntu0.33.4.4-5ubuntu0.43.4.4-5ubuntu0.53.4.4-5ubuntu0.63.4.4-5ubuntu0.73.4.4-5ubuntu0.83.4.4-5ubuntu0.93.4.4-5ubuntu0.10 |
None known |
libsoup2.4Ubuntu:26.10 |
All versions, plus listed versions 2.74.3-10.1ubuntu5 |
None known |
libsoup3Ubuntu:26.10 |
All versions, plus listed versions 3.6.6-13.6.6-1ubuntu33.6.6-1ubuntu3.1 |
None known |
libsoup3Ubuntu:26.04:LTS |
All versions, plus listed versions 3.6.5-43.6.5-53.6.5-63.6.5-73.6.5-93.6.6-13.6.6-1ubuntu0.13.6.6-1ubuntu0.2 |
None known |
libsoup2.4Ubuntu:Pro:26.04:LTS |
All versions, plus listed versions 2.74.3-10.1ubuntu42.74.3-10.1ubuntu52.74.3-10.1ubuntu5+esm12.74.3-10.1ubuntu5+esm22.74.3-10.1ubuntu5+esm32.74.3-10.1ubuntu5+esm4 |
None known |
libsoupopenSUSE:Tumbleweed From an advisory covering 10 CVEs |
before 3.8.1-1.1 | 3.8.1-1.1 |
History
| Recorded | Changed | Sources |
|---|---|---|
| affected, facts | CVE List, EUVD, NVD, OSV | |
| affected, facts | OSV | |
| first indexed | CVE List, EUVD, GitHub Advisories, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2026-66337 is a medium vulnerability (CVSS 6.5) in Gnome Libsoup, published July 24, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.25%, the 15th percentile. No source names a fixed version.
References
access.redhat.com/security/cve/CVE-2026-66337
bugzilla.redhat.com/show_bug.cgi?id=2506949
nvd.nist.gov/vuln/detail/CVE-2026-66337
github.com/advisories/GHSA-ww4c-c3rv-f96h
security-tracker.debian.org/tracker/CVE-2026-66337
openeuler.org/zh/security/security-bulletins/detail?id=openEuler-SA-2026-4389
Show 21 moreShow less
nvd.nist.gov/vuln/detail/CVE-2026-12547
openeuler.org/zh/security/security-bulletins/detail?id=openEuler-SA-2026-4390
openeuler.org/zh/security/security-bulletins/detail?id=openEuler-SA-2026-4391
nvd.nist.gov/vuln/detail/CVE-2026-66338
openeuler.org/zh/security/security-bulletins/detail?id=openEuler-SA-2026-4441
nvd.nist.gov/vuln/detail/CVE-2026-102558
nvd.nist.gov/vuln/detail/CVE-2026-102560
ubuntu.com/security/CVE-2026-66337
cve.org/CVERecord?id=CVE-2026-66337
gitlab.gnome.org/GNOME/libsoup/-/work_items/532
gitlab.gnome.org/GNOME/libsoup/-/merge_requests/557
suse.com/security/cve/CVE-2026-12547
suse.com/security/cve/CVE-2026-15709
suse.com/security/cve/CVE-2026-15711
suse.com/security/cve/CVE-2026-15712
suse.com/security/cve/CVE-2026-15713
suse.com/security/cve/CVE-2026-15714
suse.com/security/cve/CVE-2026-3099
suse.com/security/cve/CVE-2026-3633
suse.com/security/cve/CVE-2026-66337
suse.com/security/cve/CVE-2026-66339