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Fencer Intel
high 7.5

CVE-2026-81665 json

Corosync: corosync: heap-based buffer overflow in totempg assembly buffer during fragmented message reassembly

published 2mo ago modified 9d ago also EUVD-2026-70978

cvss
7.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.4%
EPSS 0.4% chance of exploitation in 30 days, percentile 36%
public exploits
0
none known

Summary

A heap-based buffer overflow was found in Corosync's Totem Process Group (totempg) message reassembly. When processing fragmented multicast messages, the buffer used to reassemble fragments lacks a runtime bounds check in release builds. A network-adjacent attacker able to send crafted multicast protocol messages to the cluster could cause a heap buffer overflow with attacker-controlled data. This can crash the Corosync daemon, causing a denial of service to the entire cluster, and may potentially allow further exploitation given sufficient heap-corruption control.

Patch / fix

  • Red Hat Red Hat Enterprise Linux 10 0:3.1.10-1.el10_2.2
  • Red Hat Red Hat Enterprise Linux 10.0 Extended Update Support 0:3.1.9-1.el10_0.3
  • Red Hat Red Hat Enterprise Linux 7 Extended Lifecycle Support 0:2.4.5-7.el7_9.4
  • Red Hat Red Hat Enterprise Linux 8 0:3.1.8-1.el8_10.2
  • Red Hat Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support 0:3.1.0-3.el8_4.3
  • Red Hat Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On 0:3.1.0-3.el8_4.3
  • Red Hat Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support 0:3.1.5-2.el8_6.2
  • Red Hat Red Hat Enterprise Linux 8.6 Extended Update Support Long-Life Add-On 0:3.1.5-2.el8_6.2
  • Red Hat Red Hat Enterprise Linux 8.8 Telecommunications Update Service 0:3.1.7-1.el8_8.2
  • Red Hat Red Hat Enterprise Linux 8.8 Update Services for SAP Solutions 0:3.1.7-1.el8_8.2
  • Red Hat Red Hat Enterprise Linux 9 0:3.1.10-1.el9_8.2
  • Red Hat Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions 0:3.1.7-1.el9_2.2
  • Red Hat Red Hat Enterprise Linux 9.4 Update Services for SAP Solutions 0:3.1.8-1.el9_4.2
  • Red Hat Red Hat Enterprise Linux 9.6 Extended Update Support 0:3.1.9-2.el9_6.2
  • corosync RHEL 8 3.1.8-1.el8_10.2
  • spausedd RHEL 8 3.1.8-1.el8_10.2
  • corosynclib RHEL 8 3.1.8-1.el8_10.2
  • corosync-vqsim RHEL 8 3.1.8-1.el8_10.2
  • corosync RHEL 7 2.4.5-7.el7_9.4
  • spausedd RHEL 7 2.4.5-7.el7_9.4
  • corosynclib RHEL 7 2.4.5-7.el7_9.4
  • corosync-qnetd RHEL 7 2.4.5-7.el7_9.4

red hat advisories RHSA-2026:69280RHSA-2026:69278RHSA-2026:69279RHSA-2026:69277RHSA-2026:67880RHSA-2026:68574

  • corosync SLES LTSS Extended Security 12 SP5, SLES 12 SP5-LTSS, SLE High Availability Extension 12 SP5 2.3.6-9.25.1
  • corosync SLE High Availability Extension 16.0 3.1.9-160000.4.1
  • corosync SLE High Availability Extension 15 SP7, SLE High Availability Extension 15 SP6, SLE High Availability Extension 15 SP5 +1 more 2.4.6-150300.12.19.1

suse advisories SUSE-SU-2026:4387-1SUSE-SU-2026:23850-1SUSE-SU-2026:4202-1

  • corosync openSUSE Leap 16.0 3.1.9-160000.4.1
  • corosync openSUSE Tumbleweed 3.1.10-5.1

opensuse advisories openSUSE-SU-2026:21887-1openSUSE-SU-2026:11715-1

  • corosync AlmaLinux 8 3.1.8-1.el8_10.2
  • spausedd AlmaLinux 8 3.1.8-1.el8_10.2
  • corosynclib AlmaLinux 8 3.1.8-1.el8_10.2
  • corosync-vqsim AlmaLinux 8 3.1.8-1.el8_10.2
  • corosync AlmaLinux 10 3.1.10-1.el10_2.2
  • corosynclib AlmaLinux 10 3.1.10-1.el10_2.2
  • corosync-vqsim AlmaLinux 10 3.1.10-1.el10_2.2
  • corosync AlmaLinux 9 3.1.10-1.el9_8.2

almalinux advisories ALSA-2026:69277ALSA-2026:67872ALSA-2026:67873

  • corosync Rocky Linux 8 3.1.8-1.el8_10.2
  • corosync Rocky Linux 10 3.1.10-1.el10_2.2
  • corosync Rocky Linux 9 3.1.10-1.el9_8.2

rocky linux advisories RLSA-2026:69277RLSA-2026:67872RLSA-2026:67873

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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-2026-81665 updated cvss 7.5

corosync: corosync: heap-based buffer overflow in totempg assembly buffer during fragmented message reassembly

  • Red Hat OpenShift Container Platform 4 openshift/ose-rhel-coreos-9 Red Hat OpenShift Container Platform 5 openshift/ose-rhel-coreos-9
    affected: workaround, no fix available
  • Red Hat CodeReady Linux Builder EUS (v.9.6) corosync-vqsim 3.1.9-2.el9_6.2
    fixed: vendor fix RHSA-2026:67879
  • Red Hat Enterprise Linux AppStream (v. 8) corosync 3.1.8-1.el8_10.2, corosynclib 3.1.8-1.el8_10.2
    fixed: vendor fix RHSA-2026:69277
  • Red Hat Enterprise Linux AppStream (v. 9) corosync 3.1.10-1.el9_8.2, corosynclib 3.1.10-1.el9_8.2
    fixed: vendor fix RHSA-2026:67873
  • Red Hat Enterprise Linux AppStream (v. 10) corosync 3.1.10-1.el10_2.2, corosynclib 3.1.10-1.el10_2.2
    fixed: vendor fix RHSA-2026:67872
  • Red Hat Enterprise Linux AppStream AUS (v.8.4) corosync 3.1.0-3.el8_4.3, corosynclib 3.1.0-3.el8_4.3
    fixed: vendor fix RHSA-2026:69280
  • Red Hat Enterprise Linux AppStream AUS (v.8.6) corosync 3.1.5-2.el8_6.2, corosynclib 3.1.5-2.el8_6.2
    fixed: vendor fix RHSA-2026:69279
  • Red Hat Enterprise Linux AppStream E4S (v.8.8) corosync 3.1.7-1.el8_8.2, corosynclib 3.1.7-1.el8_8.2
    fixed: vendor fix RHSA-2026:69278
show 31 more
  • Red Hat Enterprise Linux AppStream E4S (v.9.2) corosync 3.1.7-1.el9_2.2, corosynclib 3.1.7-1.el9_2.2
    fixed: vendor fix RHSA-2026:67880
  • Red Hat Enterprise Linux AppStream E4S (v.9.4) corosync 3.1.8-1.el9_4.2, corosynclib 3.1.8-1.el9_4.2
    fixed: vendor fix RHSA-2026:67878
  • Red Hat Enterprise Linux AppStream EUS (v. 10.0) corosync 3.1.9-1.el10_0.3, corosynclib 3.1.9-1.el10_0.3
    fixed: vendor fix RHSA-2026:67881
  • Red Hat Enterprise Linux AppStream EUS (v.9.6) corosync 3.1.9-2.el9_6.2, corosynclib 3.1.9-2.el9_6.2
    fixed: vendor fix RHSA-2026:67879
  • Red Hat Enterprise Linux AppStream EUS EXTENSION (v.8.4) corosync 3.1.0-3.el8_4.3, corosynclib 3.1.0-3.el8_4.3
    fixed: vendor fix RHSA-2026:69280
  • Red Hat Enterprise Linux AppStream EUS EXTENSION (v.8.6) corosync 3.1.5-2.el8_6.2, corosynclib 3.1.5-2.el8_6.2
    fixed: vendor fix RHSA-2026:69279
  • Red Hat Enterprise Linux AppStream TUS (v.8.8) corosync 3.1.7-1.el8_8.2, corosynclib 3.1.7-1.el8_8.2
    fixed: vendor fix RHSA-2026:69278
  • Red Hat Enterprise Linux CodeReady Linux Builder (v. 9) corosync-vqsim 3.1.10-1.el9_8.2
    fixed: vendor fix RHSA-2026:67873
  • Red Hat Enterprise Linux CodeReady Linux Builder (v. 10) corosync-vqsim 3.1.10-1.el10_2.2
    fixed: vendor fix RHSA-2026:67872
  • Red Hat Enterprise Linux CodeReady Linux Builder EUS (v. 10.0) corosync-vqsim 3.1.9-1.el10_0.3
    fixed: vendor fix RHSA-2026:67881
  • Red Hat Enterprise Linux CRB (v. 8) corosync-vqsim 3.1.8-1.el8_10.2
    fixed: vendor fix RHSA-2026:69277
  • Red Hat Enterprise Linux High Availability (v. 9) corosync 3.1.10-1.el9_8.2
    fixed: vendor fix RHSA-2026:67873
  • Red Hat Enterprise Linux High Availability (v. 10) corosync 3.1.10-1.el10_2.2
    fixed: vendor fix RHSA-2026:67872
  • Red Hat Enterprise Linux High Availability AUS (v.8.4) corosync 3.1.0-3.el8_4.3, spausedd 3.1.0-3.el8_4.3
    fixed: vendor fix RHSA-2026:69280
  • Red Hat Enterprise Linux High Availability E4S (v.8.8) corosync 3.1.7-1.el8_8.2, spausedd 3.1.7-1.el8_8.2
    fixed: vendor fix RHSA-2026:69278
  • Red Hat Enterprise Linux High Availability E4S (v.9.2) corosync 3.1.7-1.el9_2.2, corosynclib 3.1.7-1.el9_2.2
    fixed: vendor fix RHSA-2026:67880
  • Red Hat Enterprise Linux High Availability E4S (v.9.4) corosync 3.1.8-1.el9_4.2, corosynclib 3.1.8-1.el9_4.2
    fixed: vendor fix RHSA-2026:67878
  • Red Hat Enterprise Linux High Availability EUS (v. 10.0) corosync 3.1.9-1.el10_0.3
    fixed: vendor fix RHSA-2026:67881
  • Red Hat Enterprise Linux High Availability EUS (v.9.6) corosync 3.1.9-2.el9_6.2
    fixed: vendor fix RHSA-2026:67879
  • Red Hat Enterprise Linux High Availability EUS EXTENSION (v.8.6) corosync 3.1.5-2.el8_6.2, spausedd 3.1.5-2.el8_6.2
    fixed: vendor fix RHSA-2026:69279
  • Red Hat Enterprise Linux High Availability TUS (v.8.8) corosync 3.1.7-1.el8_8.2, spausedd 3.1.7-1.el8_8.2
    fixed: vendor fix RHSA-2026:69278
  • Red Hat Enterprise Linux HighAvailability (v. 8) corosync 3.1.8-1.el8_10.2, spausedd 3.1.8-1.el8_10.2
    fixed: vendor fix RHSA-2026:69277
  • Red Hat Enterprise Linux HighAvailability EUS EXTENSION (v.8.4) corosync 3.1.0-3.el8_4.3, spausedd 3.1.0-3.el8_4.3
    fixed: vendor fix RHSA-2026:69280
  • Red Hat Enterprise Linux Resilient Storage (v. 9) corosync 3.1.10-1.el9_8.2
    fixed: vendor fix RHSA-2026:67873
  • Red Hat Enterprise Linux Resilient Storage E4S (v.9.2) corosync 3.1.7-1.el9_2.2, corosynclib 3.1.7-1.el9_2.2
    fixed: vendor fix RHSA-2026:67880
  • Red Hat Enterprise Linux Resilient Storage E4S (v.9.4) corosync 3.1.8-1.el9_4.2, corosynclib 3.1.8-1.el9_4.2
    fixed: vendor fix RHSA-2026:67878
  • Red Hat Enterprise Linux Resilient Storage EUS (v.9.6) corosync 3.1.9-2.el9_6.2
    fixed: vendor fix RHSA-2026:67879
  • Red Hat Enterprise Linux Resilient Storage EUS EXTENSION (v.8.6) corosync 3.1.5-2.el8_6.2, spausedd 3.1.5-2.el8_6.2
    fixed: vendor fix RHSA-2026:69279
  • Red Hat Enterprise Linux ResilientStorage (v. 8) corosync 3.1.8-1.el8_10.2, spausedd 3.1.8-1.el8_10.2
    fixed: vendor fix RHSA-2026:69277
  • Red Hat Enterprise Linux ResilientStorage EUS EXTENSION (v.8.4) corosync 3.1.0-3.el8_4.3, spausedd 3.1.0-3.el8_4.3
    fixed: vendor fix RHSA-2026:69280
  • Red Hat Enterprise Linux Server HighAvailability (v. 7 ELS) corosync 2.4.5-7.el7_9.4, spausedd 2.4.5-7.el7_9.4, corosynclib 2.4.5-7.el7_9.4, corosync-qnetd 2.4.5-7.el7_9.4, corosync-qdevice 2.4.5-7.el7_9.4
    fixed: vendor fix RHSA-2026:68574

1 more fixed, 2 more not affected in the full advisory

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
none
Automatable
no
Technical impact
total
Assessed
2mo ago

Exploit prediction

0.42% chance of exploitation in the next 30 days, higher than 36% of all scored CVEs (FIRST EPSS, 2026-11-11).

CVSS scores

assigned by version score vector
CNA 3.1 7.5 CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:H/I:H/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 7 Extended Lifecycle Support
  • Red Hat Red Hat Enterprise Linux 8
  • 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 OpenShift Container Platform 4
  • Red Hat Red Hat OpenShift Container Platform 5

Classification

Weakness
  • CWE-122 Heap-based Buffer Overflow

References

Sources

Fencer Intel 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.