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VulnerabilityPublished Updated

CVE-2026-102559: Libsoup2.4 · A flaw was found in libsoup

Affects libsoup2.4Source GCVE Database

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Authoritative record:CVE-2026-102559· High 8.6

Not known to be exploited · CVSS 8.6 High.

Data as of 3 Nov 2026, 22:58 UTC

CVSS 3.1 base score
8.6High
How severe the flaw is on the 0–10 CVSS scale.

Thin evidence

One scorer or none
CVSS scores by source
CNA (redhat)CVSS 3.18.6
EPSS
0.6% chance of exploitation in 30 days – higher than 50% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 29 Sep 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 3 Nov 2026.

What to do

Affected software

ProductAffectedFixed in
Ubuntu 26.10libsoup2.4pkg:deb/ubuntu/libsoup2.4?arch=source&distro=stonkingOther threatsAffected
  • =2.74.3-10.1ubuntu5
Fixed in–
Ubuntu 26.10libsoup3pkg:deb/ubuntu/libsoup3?arch=source&distro=stonkingOther threatsAffected
  • =3.6.6-1
  • =3.6.6-1ubuntu3
  • =3.6.6-1ubuntu3.1
Fixed in–
Ubuntu 26.04 LTSlibsoup3pkg:deb/ubuntu/libsoup3?arch=source&distro=resoluteOther threatsAffected
  • 3.6.5-4 – 3.6.6-1ubuntu0.2
8 affected builds
Fixed in–
Ubuntu Pro 26.04 LTSlibsoup2.4pkg:deb/ubuntu/libsoup2.4?arch=source&distro=esm-apps/resoluteOther threatsAffected
  • 2.74.3-10.1ubuntu4 – 2.74.3-10.1ubuntu5+esm4
6 affected builds
Fixed in–
Ubuntu 24.04 LTSlibsoup2.4pkg:deb/ubuntu/libsoup2.4?arch=source&distro=nobleOther threatsAffected
  • 2.74.3-1 – 2.74.3-6ubuntu1.10
16 affected builds
Fixed in–
Ubuntu 24.04 LTSlibsoup3pkg:deb/ubuntu/libsoup3?arch=source&distro=nobleOther threatsAffected
  • 3.4.2-4 – 3.4.4-5ubuntu0.10
17 affected builds
Fixed in–

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

The recommended mitigation is to enforce application-level limits on outgoing WebSocket message sizes to prevent sending extremely large messages. Avoid sending untrusted bulk data as a single WebSocket message. Monitor vendor advisories for patch availability.

Description

A heap buffer overflow vulnerability exists in libsoup 2.4 when constructing a masked WebSocket client frame for very large outgoing payloads. The flaw arises because size values passed to GByteArray allocation APIs can be truncated, while the masking routine uses the full length, leading to heap corruption or denial of service in the sending process. Triggering this requires sending an extremely large WebSocket message, which may be attacker-influenced if application-level message size limits are not enforced.

References

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