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CVE-2026-102559VulnerabilityPublished Updated

libsoup · Out-of-bounds Read

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 12 Nov 2026, 23:24 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 13 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
Fixed in–
Ubuntu 26.04 LTSlibsoup3pkg:deb/ubuntu/libsoup3?arch=source&distro=resoluteOther threatsAffected
  • 3.6.5-4 – 3.6.6-1ubuntu0.1
7 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+esm3
5 affected builds
Fixed in–
Ubuntu 24.04 LTSlibsoup2.4pkg:deb/ubuntu/libsoup2.4?arch=source&distro=nobleOther threatsAffected
  • 2.74.3-1 – 2.74.3-6ubuntu1.9
15 affected builds
Fixed in–
Ubuntu 24.04 LTSlibsoup3pkg:deb/ubuntu/libsoup3?arch=source&distro=nobleOther threatsAffected
  • 3.4.2-4 – 3.4.4-5ubuntu0.9
16 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

Red Hat has released security updates for Red Hat Enterprise Linux 9 that address this vulnerability and related heap overflow issues in libsoup. Users should apply these official patches to remediate the vulnerability. No additional mitigation is specified or required beyond applying the vendor-provided updates.

Description

A heap buffer overflow vulnerability (CVE-2026-102559) exists in libsoup2.4 when constructing masked WebSocket client frames for very large outgoing payloads. The issue arises from truncation of size values passed to GByteArray allocation APIs while the masking routine uses the full length, leading to heap corruption or denial of service. Exploitation requires sending an extremely large WebSocket message, which depends on whether the application permits attacker-controlled message sizes. Red Hat has released security updates addressing this and related heap overflow issues in libsoup for Red Hat Enterprise Linux 9.

References

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