Every CVE Search/ Get API key

CVE-2026-66337

Libsoup: libsoup: heap buffer over-read via integer underflow in soup_filter_input_stream_read_until()

6.5 Medium

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

0.25%Unchanged since Jul 25, 2026
90%50%10%1%

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 MediumCVSS: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 MediumCVSS: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 MediumCVSS: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 MediumCVSS: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 MediumCVSS: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 MediumCVSS: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 MediumCVSS: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 MediumCVSS: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 HighCVSS: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 MediumCVSS: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

Affected packages
PackageAffectedFixed
libsoup
Azure Linux:3
through 3.4.4-18 None known
libsoup2.4
Debian: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 less
2.74.3-22.74.3-32.74.3-3.1~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
libsoup2.4
Debian:13
All versions, plus listed versions
2.74.3-10.12.74.3-11
None known
libsoup3
Debian: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 less
3.4.1-13.4.2-13.4.2-23.4.2-33.4.2-43.4.3-13.4.4-13.4.4-23.4.4-33.4.4-43.4.4-53.5.2-13.6.0-13.6.0-23.6.0-33.6.0-43.6.1-13.6.4-13.6.4-23.6.4-33.6.5-13.6.5-23.6.5-33.6.5-43.6.5-53.6.5-63.6.5-73.6.5-83.6.5-93.6.6-13.8.0-13.8.0-23.8.0-3
None known
libsoup3
Debian: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 less
3.6.5-83.6.5-93.6.6-13.8.0-13.8.0-23.8.0-3
None known
libsoup
openEuler:24.03-LTS-SP1
From an advisory covering 2 CVEs
before 2.74.3-29.oe2403sp1
2.74.3-29.oe2403sp1
libsoup
openEuler:24.03-LTS-SP3
From an advisory covering 2 CVEs
before 2.74.3-29.oe2403sp3
2.74.3-29.oe2403sp3
libsoup
openEuler:24.03-LTS-SP4
From an advisory covering 3 CVEs
before 2.74.3-29.oe2403sp4
2.74.3-29.oe2403sp4
libsoup
openEuler:22.03-LTS-SP4
From an advisory covering 3 CVEs
before 2.74.2-27.oe2203sp4
2.74.2-27.oe2203sp4
libsoup2.4
Ubuntu: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 less
2.52.2-1ubuntu0.32.52.2-1ubuntu0.3+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
Affected packages
PackageAffectedFixed
libsoup2.4
Ubuntu: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 less
2.62.0-12.62.1-12.62.1-1ubuntu0.12.62.1-1ubuntu0.32.62.1-1ubuntu0.42.62.1-1ubuntu0.4+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
libsoup2.4
Ubuntu: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 less
2.70.0-12.70.0-1ubuntu0.12.70.0-1ubuntu0.22.70.0-1ubuntu0.32.70.0-1ubuntu0.42.70.0-1ubuntu0.52.70.0-1ubuntu0.5+esm12.70.0-1ubuntu0.5+esm22.70.0-1ubuntu0.5+esm32.70.0-1ubuntu0.5+esm42.70.0-1ubuntu0.5+esm5
None known
libsoup2.4
Ubuntu: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 less
2.74.2-3ubuntu0.22.74.2-3ubuntu0.32.74.2-3ubuntu0.42.74.2-3ubuntu0.52.74.2-3ubuntu0.62.74.2-3ubuntu0.72.74.2-3ubuntu0.82.74.2-3ubuntu0.92.74.2-3ubuntu0.10
None known
libsoup3
Ubuntu: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 less
3.0.7-0ubuntu1+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
libsoup2.4
Ubuntu: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 less
2.74.3-6ubuntu12.74.3-6ubuntu1.12.74.3-6ubuntu1.22.74.3-6ubuntu1.32.74.3-6ubuntu1.42.74.3-6ubuntu1.52.74.3-6ubuntu1.62.74.3-6ubuntu1.72.74.3-6ubuntu1.82.74.3-6ubuntu1.92.74.3-6ubuntu1.10
None known
libsoup3
Ubuntu: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 less
3.4.4-5build13.4.4-5build23.4.4-5ubuntu0.13.4.4-5ubuntu0.23.4.4-5ubuntu0.33.4.4-5ubuntu0.43.4.4-5ubuntu0.53.4.4-5ubuntu0.63.4.4-5ubuntu0.73.4.4-5ubuntu0.83.4.4-5ubuntu0.93.4.4-5ubuntu0.10
None known
libsoup2.4
Ubuntu:26.10
All versions, plus listed versions
2.74.3-10.1ubuntu5
None known
libsoup3
Ubuntu:26.10
All versions, plus listed versions
3.6.6-13.6.6-1ubuntu33.6.6-1ubuntu3.1
None known
libsoup3
Ubuntu: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
libsoup2.4
Ubuntu: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
libsoup
openSUSE:Tumbleweed
From an advisory covering 10 CVEs
before 3.8.1-1.1
3.8.1-1.1

History

History
RecordedChangedSources
affected, factsCVE List, EUVD, NVD, OSV
affected, factsOSV
first indexedCVE 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

Show 21 moreShow less
MoveEnter Open