CVE-2026-102560
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.
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (0.42%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
Description
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.
- CVSS 3.1
- 9.8 CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- EPSS
- 0.42% probability · 36th percentile
- Public exploits
- None in Exploit-DB
- CISA KEV
- Not listed
- Weakness
- CWE-125
- Affected
- gnome/libsoup · redhat/enterprise linux
- Source
- secalert@redhat.com
EPSS moved from 0.3% on 30 September 2026 to 0.4% on 26 October 2026.
References
- https://access.redhat.com/errata/RHSA-2026:83384Third Party Advisory
- https://access.redhat.com/errata/RHSA-2026:83618Third Party Advisory
- https://access.redhat.com/security/cve/CVE-2026-102560Mitigation, Third Party Advisory
- https://bugzilla.redhat.com/show_bug.cgi?id=2543296Issue Tracking, Patch, Third Party Advisory
Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.