Skip to content
Noroxi
NVD / CVE Program· CNA redhat

CVE-2026-81665: Corosync: corosync: heap-based buffer overflow in totempg assembly buffer during fragmented message reassembly

Noroxi assessment

Priority: Monitor (action score 30/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.41% (FIRST EPSS).
  • Someone on the same network segment can trigger it. No account or password is required. No user action is required. Special conditions such as timing or configuration are required.
  • Fixed version: corosync (AlmaLinux:10) 3.1.10-1.el10_2.2; corosync-vqsim (AlmaLinux:10) 3.1.10-1.el10_2.2; corosynclib (AlmaLinux:10) 3.1.10-1.el10_2.2.

Low priority for now. Upgrade to corosync (AlmaLinux:10) 3.1.10-1.el10_2.2; corosync-vqsim (AlmaLinux:10) 3.1.10-1.el10_2.2; corosynclib (AlmaLinux:10) 3.1.10-1.el10_2.2 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

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.

HighCVSS 7.5 · v3.1—No exploit Fix available
Published
Sep 4, 2026
Updated
Nov 2, 2026
EPSS
0.4% · 36th percentile

Report tools

JSON

Action score

30

Monitor

Low priority for now.

CVSS
30 / 40 · 7.5 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.4%

CISA SSVC decision

Exploitation
none
Automatable
no
Technical impact
total

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
—
CNA · redhat
7.5
NVD has not scored this yet; the score shown is the CNA’s.

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

If any of these changes, we'll tell you in the daily email digest.

Follow CVE-2026-81665

When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

One daily email digest (06:00 UTC); connect a webhook for KEV listings and weaponized exploits instantly.

Your free account also gets you

Running WordPress? Scan your site free with WP Lens

  • Stack alerts: add the products and versions you run, get the new CVEs that affect them
  • Uptime monitoring: 1 site, instant email when it goes down
  • Add your domain: subdomains and takeover risk scanned every week (1 domain)
  • 10 scans an hour on the security tools (3 a day without an account), an API key and MCP
  • All your scans in one panel: findings, what changed in the last scan, a report per domain or per client (PDF, share link)
All free tools

Sign up with email · Have an account? Sign in

Free account, no card. Unfollow any time.

Don't want an account? Get "Exploited this week" by email every MondayDon't want an account? RSS feed for red hat records

Running WordPress? Scan your site free with WP Lens

Is your version affected? Check it

Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

We use this product, ask for help

Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

—

Versions reported by the vendor

Affected version ranges reported by the assigning authority (redhat). Independent of NVD's CPE analysis and usually ahead of it.

  • Red Hat Red Hat Enterprise Linux 10

    • 0:3.1.10-1.el10_2.2 and laternot affected · rpm

  • Red Hat Red Hat Enterprise Linux 10.0 Extended Update Support

    • 0:3.1.9-1.el10_0.3 and laternot affected · rpm

  • Red Hat Red Hat Enterprise Linux 7 Extended Lifecycle Support

    • 0:2.4.5-7.el7_9.4 and laternot affected · rpm

  • Red Hat Red Hat Enterprise Linux 8

    • 0:3.1.8-1.el8_10.2 and laternot affected · rpm

  • Red Hat Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support

    • 0:3.1.0-3.el8_4.3 and laternot affected · rpm

  • Red Hat Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On

    • 0:3.1.0-3.el8_4.3 and laternot affected · rpm

  • Red Hat Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support

    • 0:3.1.5-2.el8_6.2 and laternot affected · rpm

  • Red Hat Red Hat Enterprise Linux 8.6 Extended Update Support Long-Life Add-On

    • 0:3.1.5-2.el8_6.2 and laternot affected · rpm

  • Red Hat Red Hat Enterprise Linux 8.8 Telecommunications Update Service

    • 0:3.1.7-1.el8_8.2 and laternot affected · rpm

  • Red Hat Red Hat Enterprise Linux 8.8 Update Services for SAP Solutions

    • 0:3.1.7-1.el8_8.2 and laternot affected · rpm

  • Red Hat Red Hat Enterprise Linux 9

    • 0:3.1.10-1.el9_8.2 and laternot affected · rpm

  • Red Hat Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions

    • 0:3.1.7-1.el9_2.2 and laternot affected · rpm

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
AlmaLinux:10corosyncbefore 3.1.10-1.el10_2.23.1.10-1.el10_2.2
AlmaLinux:10corosync-vqsimbefore 3.1.10-1.el10_2.23.1.10-1.el10_2.2
AlmaLinux:10corosynclibbefore 3.1.10-1.el10_2.23.1.10-1.el10_2.2
AlmaLinux:10corosynclib-develbefore 3.1.10-1.el10_2.23.1.10-1.el10_2.2
AlmaLinux:8corosyncbefore 3.1.8-1.el8_10.23.1.8-1.el8_10.2
AlmaLinux:8corosync-vqsimbefore 3.1.8-1.el8_10.23.1.8-1.el8_10.2
AlmaLinux:8corosynclibbefore 3.1.8-1.el8_10.23.1.8-1.el8_10.2
AlmaLinux:8corosynclib-develbefore 3.1.8-1.el8_10.23.1.8-1.el8_10.2
AlmaLinux:8spauseddbefore 3.1.8-1.el8_10.23.1.8-1.el8_10.2
AlmaLinux:9corosyncbefore 3.1.10-1.el9_8.23.1.10-1.el9_8.2
AlmaLinux:9corosync-vqsimbefore 3.1.10-1.el9_8.23.1.10-1.el9_8.2
AlmaLinux:9corosynclibbefore 3.1.10-1.el9_8.23.1.10-1.el9_8.2
AlmaLinux:9corosynclib-develbefore 3.1.10-1.el9_8.23.1.10-1.el9_8.2
Debian:12corosyncfrom 0—
openSUSE:Leap 16.0corosyncbefore 3.1.9-160000.4.13.1.9-160000.4.1
openSUSE:Tumbleweedcorosyncbefore 3.1.10-5.13.1.10-5.1
Red Hat:enterprise_linux_eus:10.0corosyncbefore 0:3.1.9-1.el10_0.30:3.1.9-1.el10_0.3
Red Hat:enterprise_linux_eus:10.0corosync-debuginfobefore 0:3.1.9-1.el10_0.30:3.1.9-1.el10_0.3
Red Hat:enterprise_linux_eus:10.0corosync-debugsourcebefore 0:3.1.9-1.el10_0.30:3.1.9-1.el10_0.3
Red Hat:enterprise_linux_eus:10.0corosync-vqsimbefore 0:3.1.9-1.el10_0.30:3.1.9-1.el10_0.3
Red Hat:enterprise_linux_eus:10.0corosync-vqsim-debuginfobefore 0:3.1.9-1.el10_0.30:3.1.9-1.el10_0.3
Red Hat:enterprise_linux_eus:10.0corosynclibbefore 0:3.1.9-1.el10_0.30:3.1.9-1.el10_0.3
Red Hat:enterprise_linux_eus:10.0corosynclib-debuginfobefore 0:3.1.9-1.el10_0.30:3.1.9-1.el10_0.3
Red Hat:enterprise_linux_eus:10.0corosynclib-develbefore 0:3.1.9-1.el10_0.30:3.1.9-1.el10_0.3

+88

Same product

red hat: all records

Other highest-scoring records for the same primary product.

  • CVE-2025-10230Samba: command injection in wins server hook script
    52Plan
  • CVE-2026-4631Cockpit: cockpit: unauthenticated remote code execution due to ssh command-line argument injection
    44Plan
  • CVE-2026-76578Ipa: freeipa: freeipa: unauthenticated ldap client can obtain administrator credentials via the self-managed-token aci
    39Monitor

Published before and after this one in the same product

  • ← EarlierCVE-2026-85150Sep 3, 2026 · Gstreamer1-plugins-base: gstreamer: null/invalid-pointer dereference in gst_rtsp_message_parse_auth_credentials() when parsing a crafted digest authorization/ww
    30Monitor
  • ← EarlierCVE-2026-85197Sep 4, 2026 · Libsoup: libsoup: heap use-after-free in libsoup http/2 client on_data_read() via goaway during body upload
    30Monitor
  • Later →CVE-2026-81666Sep 4, 2026 · Corosync: corosync: integer overflow in check_memb_commit_token_sanity may bypass message length validation on 32-bit systems
    26Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
almalinux:corosync3.1.10-1.el10_2.2 · AlmaLinux:10Package registry (OSV)
almalinux:corosync3.1.10-1.el9_8.2 · AlmaLinux:9Package registry (OSV)
almalinux:corosync-vqsim3.1.10-1.el10_2.2 · AlmaLinux:10Package registry (OSV)
almalinux:corosync-vqsim3.1.10-1.el9_8.2 · AlmaLinux:9Package registry (OSV)
almalinux:corosynclib3.1.10-1.el10_2.2 · AlmaLinux:10Package registry (OSV)
almalinux:corosynclib3.1.10-1.el9_8.2 · AlmaLinux:9Package registry (OSV)
almalinux:corosynclib-devel3.1.10-1.el10_2.2 · AlmaLinux:10Package registry (OSV)
almalinux:corosynclib-devel3.1.10-1.el9_8.2 · AlmaLinux:9Package registry (OSV)
almalinux:spausedd3.1.8-1.el8_10.2 · AlmaLinux:8Package registry (OSV)
opensuse:corosync3.1.10-5.1 · openSUSE:TumbleweedPackage registry (OSV)
red hat:corosync0:3.1.10-1.el10_2.2 · Red Hat:enterprise_linux:10.2Package registry (OSV)
red hat:corosync-debuginfo0:3.1.10-1.el10_2.2 · Red Hat:enterprise_linux:10.2Package registry (OSV)
red hat:corosync-debugsource0:3.1.10-1.el10_2.2 · Red Hat:enterprise_linux:10.2Package registry (OSV)
red hat:corosync-qdevice0:2.4.5-7.el7_9.4 · Red Hat:enterprise_linux:7::serverPackage registry (OSV)
red hat:corosync-qnetd0:2.4.5-7.el7_9.4 · Red Hat:enterprise_linux:7::serverPackage registry (OSV)
red hat:corosync-vqsim0:3.1.10-1.el10_2.2 · Red Hat:enterprise_linux:10.2Package registry (OSV)
red hat:corosync-vqsim-debuginfo0:3.1.10-1.el10_2.2 · Red Hat:enterprise_linux:10.2Package registry (OSV)
red hat:corosynclib0:3.1.10-1.el10_2.2 · Red Hat:enterprise_linux:10.2Package registry (OSV)
red hat:corosynclib-debuginfo0:3.1.10-1.el10_2.2 · Red Hat:enterprise_linux:10.2Package registry (OSV)
red hat:corosynclib-devel0:3.1.10-1.el10_2.2 · Red Hat:enterprise_linux:10.2Package registry (OSV)
red hat:spausedd0:2.4.5-7.el7_9.4 · Red Hat:enterprise_linux:7::serverPackage registry (OSV)
red hat:spausedd-debuginfo0:3.1.8-1.el8_10.2 · Red Hat:enterprise_linux:8::appstreamPackage registry (OSV)
rocky linux:corosync0:3.1.10-1.el10_2.2 · Rocky Linux:10Package registry (OSV)
suse:corosync3.1.9-160000.4.1 · SUSE:Linux Enterprise High Availability Extension 16.0Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

  • CVE-2026-5272081 days apartGstreamer1-plugins-bad-free: gstreamer: heap buffer overflow via crafted vnc server rectangle in librfb
    35Monitor
  • CVE-2026-12199762 days apartGdb: gdbserver: heap buffer overflow in cmd_qtdpsrc via qtdpsrc declared/actual length mismatch
    32Monitor
  • CVE-2026-10716133 days apartCyrus-sasl: heap buffer overflow in cyrus-sasl add_to_challenge() allows malicious server to crash or compromise digest-md5 clients
    30Monitor
  • CVE-2026-1291267 days apartLibtiff: libtiff: heap-based buffer overflow via crafted pixarlog-compressed tiff image
    29Monitor
  • CVE-2026-319577 days apartQemu-kvm: virtio-snd: heap buffer overflow in virtio_snd_pcm_in_cb (incomplete fix for cve-2024-7730)
    29Monitor
  • CVE-2026-10324226 days apartRpm: heap-based buffer overflow write in hex2binv() via a mistyped rpmtag_filesignatures header tag
    28Monitor

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

  • Someone on the same network segment can trigger it.
  • No account or password is required.
  • No user action is required.
  • Special conditions such as timing or configuration are required.

If successful

Confidentiality
high · data can be read
Integrity
high · data or configuration can be modified
Availability
high · the service can be disrupted
Attack vector
Adjacent
Attack complexity
High
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality impact
High
Integrity impact
High
Availability impact
High

Weakness class (CWE)

CWE-122 · Heap-based Buffer Overflow

CVSS vector

CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

nvd-secondary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

ATT&CK techniques

—

Change log

  1. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Show all references (12 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records