CVE-2026-15709 json
Soupwebsocketextensiondeflate: libsoup: libsoup: websocket permessage-deflate unbounded decompression remote denial of service
published 2026-07-14 3 mo ago modified 2026-11-05 3 d ago also EUVD-2026-44408
- cvss
- 7.5
- version 3.1, CNA
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 0.9%
- EPSS 0.9% chance of exploitation in 30 days, percentile 59%
- public exploits
- 0
- none known
Summary
A flaw was found in libsoup's WebSocket implementation when using the permessage-deflate extension. The extension's decompression loop (inflate()) processes data in chunks without enforcing an upper boundary limit on the output buffer size. While libsoup limits the incoming compressed frame size via max_incoming_payload_size, it fails to track or limit memory allocation during decompression. A separate check for decompressed size (max_total_message_size) exists but executes only after inflation is complete, and it is entirely disabled by default for client connections. A remote, unauthenticated attacker can exploit this by sending a small, highly compressed payload (a decompression bomb), causing unbounded memory allocation that triggers an Out-of-Memory (OOM) crash and a Denial of Service (DoS).
Patch / fix
- Red Hat Red Hat Enterprise Linux 10 0:3.6.5-3.el10_2.14
- Red Hat Red Hat Enterprise Linux 10.0 Extended Update Support 0:3.6.5-3.el10_0.17
- Red Hat Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support 0:2.62.3-2.el8_4.10
- Red Hat Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On 0:2.62.3-2.el8_4.10
- Red Hat Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support 0:2.62.3-2.el8_6.10
- Red Hat Red Hat Enterprise Linux 8.6 Extended Update Support Long-Life Add-On 0:2.62.3-2.el8_6.10
- Red Hat Red Hat Enterprise Linux 8.8 Telecommunications Update Service 0:2.62.3-3.el8_8.11
- Red Hat Red Hat Enterprise Linux 8.8 Update Services for SAP Solutions 0:2.62.3-3.el8_8.11
- Red Hat Red Hat Enterprise Linux 9 0:2.72.0-16.el9_8.3
- Red Hat Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions 0:2.72.0-8.el9_2.13
- Red Hat Red Hat Enterprise Linux 9.4 Update Services for SAP Solutions 0:2.72.0-8.el9_4.12
- Red Hat Red Hat Enterprise Linux 9.6 Extended Update Support 0:2.72.0-10.el9_6.9
- libsoup3 RHEL 10.2 3.6.5-3.el10_2.14
- libsoup RHEL 9 2.72.0-16.el9_8.3
- libsoup3 enterprise linux eus 10.0 3.6.5-3.el10_0.17
- libsoup RHEL 8.4 EUS_LONG_LIFE, RHEL 8.4 AUS 2.62.3-2.el8_4.10
- libsoup RHEL 8.6 EUS_LONG_LIFE, RHEL 8.6 AUS 2.62.3-2.el8_6.10
- libsoup RHEL 8.8 TUS, RHEL 8.8 E4S 2.62.3-3.el8_8.11
- libsoup RHEL 9.2 E4S 2.72.0-8.el9_2.13
- libsoup RHEL 9.4 E4S 2.72.0-8.el9_4.12
red hat advisories RHSA-2026:71389RHSA-2026:70599RHSA-2026:70598RHSA-2026:69863RHSA-2026:69297RHSA-2026:69108
- libsoup openSUSE Tumbleweed 3.8.1-1.1
opensuse advisories openSUSE-SU-2026:12365-1
- libsoup AlmaLinux 9 2.72.0-16.el9_8.3
- libsoup3 AlmaLinux 10 3.6.5-3.el10_2.14
almalinux advisories ALSA-2026:68234ALSA-2026:68235
- libsoup Rocky Linux 9 2.72.0-16.el9_8.3
rocky linux advisories RLSA-2026:68234
Vendor advisories
What the vendors themselves say about their products: affected, fixed or not affected, and what to do.
red hat product security vex CVE-2026-15709 updated cvss 7.5
SoupWebsocketExtensionDeflate: libsoup: libsoup: WebSocket permessage-deflate Unbounded Decompression Remote Denial of Service
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Red Hat Enterprise Linux 6 libsoup Red Hat Enterprise Linux 7 libsoupaffected: workaround, no fix planned “Out of support scope”
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Red Hat Enterprise Linux 8 libsoupaffected: workaround, no fix available
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Red Hat Enterprise Linux AppStream (v. 9) libsoup 2.72.0-16.el9_8.3fixed: vendor fix RHSA-2026:68234
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Red Hat Enterprise Linux AppStream (v. 10) libsoup3 3.6.5-3.el10_2.14fixed: vendor fix RHSA-2026:68235
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Red Hat Enterprise Linux AppStream AUS (v.8.4) libsoup-devel 2.62.3-2.el8_4.10, libsoup-debuginfo 2.62.3-2.el8_4.10, libsoup-debugsource 2.62.3-2.el8_4.10fixed: vendor fix RHSA-2026:70599
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Red Hat Enterprise Linux AppStream AUS (v.8.6) libsoup-devel 2.62.3-2.el8_6.10, libsoup-debuginfo 2.62.3-2.el8_6.10, libsoup-debugsource 2.62.3-2.el8_6.10fixed: vendor fix RHSA-2026:70598
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Red Hat Enterprise Linux AppStream E4S (v.8.8) libsoup-devel 2.62.3-3.el8_8.11, libsoup-debuginfo 2.62.3-3.el8_8.11, libsoup-debugsource 2.62.3-3.el8_8.11fixed: vendor fix RHSA-2026:69863
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Red Hat Enterprise Linux AppStream E4S (v.9.2) libsoup 2.72.0-8.el9_2.13fixed: vendor fix RHSA-2026:69297
show 14 moreshow fewer
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Red Hat Enterprise Linux AppStream E4S (v.9.4) libsoup 2.72.0-8.el9_4.12fixed: vendor fix RHSA-2026:69108
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Red Hat Enterprise Linux AppStream EUS (v. 10.0) libsoup3 3.6.5-3.el10_0.17fixed: vendor fix RHSA-2026:71389
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Red Hat Enterprise Linux AppStream EUS (v.9.6) libsoup 2.72.0-10.el9_6.9fixed: vendor fix RHSA-2026:68612
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Red Hat Enterprise Linux AppStream EUS EXTENSION (v.8.4) libsoup-devel 2.62.3-2.el8_4.10, libsoup-debuginfo 2.62.3-2.el8_4.10, libsoup-debugsource 2.62.3-2.el8_4.10fixed: vendor fix RHSA-2026:70599
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Red Hat Enterprise Linux AppStream EUS EXTENSION (v.8.6) libsoup-devel 2.62.3-2.el8_6.10, libsoup-debuginfo 2.62.3-2.el8_6.10, libsoup-debugsource 2.62.3-2.el8_6.10fixed: vendor fix RHSA-2026:70598
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Red Hat Enterprise Linux AppStream TUS (v.8.8) libsoup-devel 2.62.3-3.el8_8.11, libsoup-debuginfo 2.62.3-3.el8_8.11, libsoup-debugsource 2.62.3-3.el8_8.11fixed: vendor fix RHSA-2026:69863
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Red Hat Enterprise Linux BaseOS AUS (v.8.4) libsoup 2.62.3-2.el8_4.10fixed: vendor fix RHSA-2026:70599
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Red Hat Enterprise Linux BaseOS AUS (v.8.6) libsoup 2.62.3-2.el8_6.10fixed: vendor fix RHSA-2026:70598
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Red Hat Enterprise Linux BaseOS E4S (v.8.8) libsoup 2.62.3-3.el8_8.11fixed: vendor fix RHSA-2026:69863
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Red Hat Enterprise Linux BaseOS EUS EXTENSION (v.8.4) libsoup 2.62.3-2.el8_4.10fixed: vendor fix RHSA-2026:70599
-
Red Hat Enterprise Linux BaseOS EUS EXTENSION (v.8.6) libsoup 2.62.3-2.el8_6.10fixed: vendor fix RHSA-2026:70598
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Red Hat Enterprise Linux BaseOS TUS (v.8.8) libsoup 2.62.3-3.el8_8.11fixed: vendor fix RHSA-2026:69863
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Red Hat Enterprise Linux CodeReady Linux Builder (v. 10) libsoup3-doc 3.6.5-3.el10_2.14fixed: vendor fix RHSA-2026:68235
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Red Hat Enterprise Linux CodeReady Linux Builder EUS (v. 10.0) libsoup3-doc 3.6.5-3.el10_0.17fixed: vendor fix RHSA-2026:71389
Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf
CISA SSVC
- Exploitation
- Proof of concept is public
- Automatable
- yes
- Technical impact
- partial
- Assessed
- 3 mo ago
Exploit prediction
0.88% chance of exploitation in the next 30 days, higher than 59% of all scored CVEs (FIRST EPSS, 2026-11-08).
Exploits and checks
- gitlab.gnome.org https://gitlab.gnome.org/GNOME/libsoup/-/issues/511 referenced PoC, tagged "exploit" by a source, unverified
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CNA | 3.1 | 7.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H |
Affected products
- Red Hat Red Hat Enterprise Linux 10
- Red Hat Red Hat Enterprise Linux 10.0 Extended Update Support
- Red Hat Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support
- Red Hat Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On
- Red Hat Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support
- Red Hat Red Hat Enterprise Linux 8.6 Extended Update Support Long-Life Add-On
- Red Hat Red Hat Enterprise Linux 8.8 Telecommunications Update Service
- Red Hat Red Hat Enterprise Linux 8.8 Update Services for SAP Solutions
- Red Hat Red Hat Enterprise Linux 9
- Red Hat Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions
- Red Hat Red Hat Enterprise Linux 9.4 Update Services for SAP Solutions
- Red Hat Red Hat Enterprise Linux 9.6 Extended Update Support
- Red Hat Red Hat Enterprise Linux 6
- Red Hat Red Hat Enterprise Linux 7
- Red Hat Red Hat Enterprise Linux 8
Classification
- Weakness
-
- CWE-409 Improper Handling of Highly Compressed Data (Data Amplification)
References
-
gitlab.gnome.org
/GNOME/libsoup/-/issues/511
exploit
-
access.redhat.com
/errata/RHSA-2026:68234
vendor-advisory
-
access.redhat.com
/errata/RHSA-2026:68235
vendor-advisory
-
access.redhat.com
/errata/RHSA-2026:68612
vendor-advisory
-
access.redhat.com
/errata/RHSA-2026:69108
vendor-advisory
-
access.redhat.com
/errata/RHSA-2026:69297
vendor-advisory
-
access.redhat.com
/errata/RHSA-2026:69863
vendor-advisory
-
access.redhat.com
/errata/RHSA-2026:70598
vendor-advisory
-
access.redhat.com
/errata/RHSA-2026:70599
vendor-advisory
-
access.redhat.com
/errata/RHSA-2026:71389
vendor-advisory
-
access.redhat.com
/security/cve/CVE-2026-15709
vdb-entry
-
bugzilla.redhat.com
/show_bug.cgi?id=2499922
issue-tracking
Sources
- CVE List CVE-2026-15709
- NVD CVE-2026-15709
Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.