CVE-2026-2436
Libsoup: libsoup: denial of service via use-after-free in soupserver during tls handshake
CVE-2026-2436 is a medium vulnerability (CVSS 6.5) in Gnome Libsoup, published March 26, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.46%, the 39th percentile. Fixed in libsoup 3.4.4-15.
A flaw was found in libsoup's SoupServer. A remote attacker could exploit a use-after-free vulnerability where the soup_server_disconnect() function frees connection objects prematurely, even if a TLS handshake is still pending. If the handshake completes after the connection object has been freed, a dangling pointer is accessed, leading to a server crash and a Denial of Service.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- High
- Privileges needed
- None
- User interaction
- None
What an attacker can affect
- Confidentiality
- None
- Integrity
- Low
- Availability
- High
Exploit likelihood
What each source reports
CVE List Score used
6.5
Libsoup: libsoup: denial of service via use-after-free in soupserver during tls handshake
A flaw was found in libsoup's SoupServer. A remote attacker could exploit a use-after-free vulnerability where the soup_server_disconnect() function frees connection objects prematurely, even if a TLS handshake is still pending. If the handshake completes after the connection object has been freed, a dangling pointer is accessed, leading to a server crash and a Denial of Service.
- Record
CVE-2026-2436- CVSS 3.1
- 6.5 Medium
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:H - Weakness
- CWE-825
- Updated
- 2026-11-02
EUVDEUVD-2026-16342
6.5
A flaw was found in libsoup's SoupServer. A remote attacker could exploit a use-after-free vulnerability where the soup_server_disconnect() function frees connection objects prematurely, even if a TLS handshake is still pending. If the handshake completes after the connection object has been freed, a dangling pointer is accessed, leading to a server crash and a Denial of Service.
- Record
EUVD-2026-16342- CVSS 3.1
- 6.5 Medium
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:H - Updated
- 2026-11-02
GitHub AdvisoriesGHSA-wpfw-5xvc-wq9w
6.5
A flaw was found in libsoup's SoupServer. A remote attacker could exploit a use-after-free...
A flaw was found in libsoup's SoupServer. A remote attacker could exploit a use-after-free vulnerability where the soup_server_disconnect() function frees connection objects prematurely, even if a TLS handshake is still pending. If the handshake completes after the connection object has been freed, a dangling pointer is accessed, leading to a server crash and a Denial of Service.
- Record
GHSA-wpfw-5xvc-wq9w- CVSS 3.1
- 6.5 Medium
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:H - Weakness
- CWE-825
- Updated
- 2026-11-02
NVD
6.5
A flaw was found in libsoup's SoupServer. A remote attacker could exploit a use-after-free vulnerability where the soup_server_disconnect() function frees connection objects prematurely, even if a TLS handshake is still pending. If the handshake completes after the connection object has been freed, a dangling pointer is accessed, leading to a server crash and a Denial of Service.
- Record
CVE-2026-2436- CVSS 3.1
- 6.5 Medium
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:H - CVSS 3.1
- 8.2 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H - Weakness
- CWE-825
- Updated
- 2026-11-02
OSVDEBIAN-CVE-2026-2436
8.2
A flaw was found in libsoup's SoupServer. A remote attacker could exploit a use-after-free vulnerability where the soup_server_disconnect() function frees connection objects prematurely, even if a TLS handshake is still pending. If the handshake completes after the connection object has been freed, a dangling pointer is accessed, leading to a server crash and a Denial of Service.
- Record
DEBIAN-CVE-2026-2436- CVSS 3.1
- 8.2 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H - Updated
- 2026-11-02
OSVOESA-2026-2666
7.5
libsoup3 security update
Libsoup is an HTTP library implementation in C. It was originally part of a SOAP (Simple Object Access Protocol) implementation called Soup, but the SOAP and non-SOAP parts have now been split into separate packages.
Security Fix(es):
A flaw was found in libsoup. The SoupWebsocketConnection may accept a large WebSocket message, which may cause libsoup to allocate memory and lead to a denial of service (DoS).(CVE-2025-32049)
A flaw was found in libsoup. The libsoup append_param_quoted() function may contain an overflow bug resulting in a buffer under-read.(CVE-2025-32050)
A flaw was found in libsoup. The libsoup soup_uri_decode_data_uri() function may crash when processing malformed data URI. This flaw allows an attacker to cause a denial of service (DoS).(CVE-2025-32051)
A flaw was found in libsoup. The implementation of HTTP range requests is vulnerable to a resource consumption attack. This flaw allows a malicious client to request the same range many times in a single HTTP request, causing the server to use large amounts of memory. This does not allow for a full denial of service.(CVE-2025-32907)
A flaw was found in SoupServer. This HTTP request smuggling vulnerability occurs because SoupServer improperly handles requests that combine Transfer-Encoding: chunked and Connection: keep-alive headers. A remote, unauthenticated client can exploit this by sending specially crafted requests, causing SoupServer to fail to close the connection as required by RFC 9112. This allows the attacker to smuggle additional requests over the persistent connection, leading to unintended request processing and potential denial-of-service (DoS) conditions.(CVE-2026-1760)
A flaw was found in libsoup's SoupServer. A remote attacker could exploit a use-after-free vulnerability where the soup_server_disconnect() function frees connection objects prematurely, even if a TLS handshake is still pending. If the handshake completes after the connection object has been freed, a dangling pointer is accessed, leading to a server crash and a Denial of Service.(CVE-2026-2436)
A request smuggling vulnerability exists in libsoup's HTTP/1 header parsing logic. The soup_message_headers_append_common() function in libsoup/soup-message-headers.c unconditionally appends each header value without validating for duplicate or conflicting Content-Length fields. This allows an attacker to send HTTP requests containing multiple Content-Length headers with differing values.(CVE-2026-2708)
- Record
OESA-2026-2666- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - Updated
- 2026-11-02
Show 5 moreShow less
OSVOESA-2026-2667
7.5
libsoup3 security update
Libsoup is an HTTP library implementation in C. It was originally part of a SOAP (Simple Object Access Protocol) implementation called Soup, but the SOAP and non-SOAP parts have now been split into separate packages.
Security Fix(es):
A flaw was found in libsoup. The SoupWebsocketConnection may accept a large WebSocket message, which may cause libsoup to allocate memory and lead to a denial of service (DoS).(CVE-2025-32049)
A flaw was found in libsoup. The implementation of HTTP range requests is vulnerable to a resource consumption attack. This flaw allows a malicious client to request the same range many times in a single HTTP request, causing the server to use large amounts of memory. This does not allow for a full denial of service.(CVE-2025-32907)
A flaw was found in libsoup's SoupServer. A remote attacker could exploit a use-after-free vulnerability where the soup_server_disconnect() function frees connection objects prematurely, even if a TLS handshake is still pending. If the handshake completes after the connection object has been freed, a dangling pointer is accessed, leading to a server crash and a Denial of Service.(CVE-2026-2436)
A request smuggling vulnerability exists in libsoup's HTTP/1 header parsing logic. The soup_message_headers_append_common() function in libsoup/soup-message-headers.c unconditionally appends each header value without validating for duplicate or conflicting Content-Length fields. This allows an attacker to send HTTP requests containing multiple Content-Length headers with differing values.(CVE-2026-2708)
- Record
OESA-2026-2667- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - Updated
- 2026-11-02
OSVROOT-OS-DEBIAN-12-CVE-2026-2436
8.2
CVE-2026-2436 in libsoup2.4 - Patched by Root
Root has patched CVE-2026-2436 in the libsoup2.4 package for Root:Debian:12. Multiple fixed versions available.
- Record
ROOT-OS-DEBIAN-12-CVE-2026-2436- CVSS 3.1
- 8.2 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H - Updated
- 2026-11-02
OSVROOT-OS-DEBIAN-13-CVE-2026-2436
8.2
CVE-2026-2436 in libsoup3 - Patched by Root
Root has patched CVE-2026-2436 in the libsoup3 package for Root:Debian:13. Multiple fixed versions available.
- Record
ROOT-OS-DEBIAN-13-CVE-2026-2436- CVSS 3.1
- 8.2 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H - Updated
- 2026-11-02
OSVUBUNTU-CVE-2026-2436
6.5
A flaw was found in libsoup's SoupServer. A remote attacker could exploit a use-after-free vulnerability where the soup_server_disconnect() function frees connection objects prematurely, even if a TLS handshake is still pending. If the handshake completes after the connection object has been freed, a dangling pointer is accessed, leading to a server crash and a Denial of Service.
- Record
UBUNTU-CVE-2026-2436- CVSS 3.1
- 6.5 Medium
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:H - CVSS 3.1
- 8.2 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H - Updated
- 2026-11-03
OSVAZL-81519 No score
CVE-2026-2436 affecting package libsoup for versions less than 3.4.4-15
A flaw was found in libsoup's SoupServer. A remote attacker could exploit a use-after-free vulnerability where the soup_server_disconnect() function frees connection objects prematurely, even if a TLS handshake is still pending. If the handshake completes after the connection object has been freed, a dangling pointer is accessed, leading to a server crash and a Denial of Service.
- Record
AZL-81519- Updated
- 2026-11-02
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
libsoupAzure Linux:3 |
before 3.4.4-15 | 3.4.4-15 |
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 |
libsoup3openEuler:24.03-LTS-SP1 |
before 3.4.5-19.oe2403sp1 | 3.4.5-19.oe2403sp1 |
libsoup3openEuler:24.03-LTS-SP3 |
before 3.4.5-19.oe2403sp3 | 3.4.5-19.oe2403sp3 |
libsoup2.4Root:Debian:12 |
before 2.74.3-1+deb12u1.aikido.3 | 2.74.3-1+deb12u1.aikido.32.74.3-1+deb12u1.aikido.42.74.3-1+deb12u1.aikido.5 |
rootio-libsoup2.4Root:Debian:12 |
before 2.74.3-1+deb12u1.aikido.3 | 2.74.3-1+deb12u1.aikido.32.74.3-1+deb12u1.aikido.42.74.3-1+deb12u1.aikido.5 |
libsoup3Root:Debian:13 |
before 3.6.5-3.aikido.4 | 3.6.5-3.aikido.43.6.5-3.aikido.33.6.5-3.root.io.13.6.5-3.root.io.23.6.5-3.aikido.53.6.5-3.aikido.63.6.5-3.aikido.73.6.5-3.aikido.8 |
Show 6 moreShow less
| Package | Affected | Fixed |
|---|---|---|
rootio-libsoup3Root:Debian:13 |
before 3.6.5-3.aikido.4 | 3.6.5-3.aikido.43.6.5-3.aikido.33.6.5-3.root.io.13.6.5-3.root.io.23.6.5-3.aikido.53.6.5-3.aikido.63.6.5-3.aikido.73.6.5-3.aikido.8 |
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 |
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 |
libsoup3Ubuntu:25.10 |
All versions, plus listed versions 3.6.5-13.6.5-1ubuntu13.6.5-33.6.5-43.6.5-4ubuntu0.13.6.5-4ubuntu0.2 |
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 |
History
| When | Changed | Sources |
|---|---|---|
| 2026-11-03 | affected, facts | OSV |
| 2026-11-02 | created | CVE List, EUVD, GitHub Advisories, NVD, OSV |
References
access.redhat.com/security/cve/CVE-2026-2436
bugzilla.redhat.com/show_bug.cgi?id=2442909
gitlab.gnome.org/GNOME/libsoup/-/issues/501
nvd.nist.gov/vuln/detail/CVE-2026-2436
github.com/advisories/GHSA-wpfw-5xvc-wq9w
security-tracker.debian.org/tracker/CVE-2026-2436
Show 10 moreShow less
openeuler.org/zh/security/security-bulletins/detail?id=openEuler-SA-2026-2666
nvd.nist.gov/vuln/detail/CVE-2025-32049
nvd.nist.gov/vuln/detail/CVE-2025-32050
nvd.nist.gov/vuln/detail/CVE-2025-32051
nvd.nist.gov/vuln/detail/CVE-2025-32907
nvd.nist.gov/vuln/detail/CVE-2026-1760
nvd.nist.gov/vuln/detail/CVE-2026-2708
openeuler.org/zh/security/security-bulletins/detail?id=openEuler-SA-2026-2667
ubuntu.com/security/CVE-2026-2436
cve.org/CVERecord?id=CVE-2026-2436