Bug 2528437 - CVE-2026-81665 corosync: corosync: heap-based buffer overflow in totempg assembly buffer during fragmented message reassembly [fedora-all]
Summary: CVE-2026-81665 corosync: corosync: heap-based buffer overflow in totempg asse...
Keywords:
Status: CLOSED ERRATA
Alias: None
Product: Fedora
Classification: Fedora
Component: corosync
Version: rawhide
Hardware: Unspecified
OS: Unspecified
high
high
Target Milestone: ---
Assignee: Jan Friesse
QA Contact: Fedora Extras Quality Assurance
URL:
Whiteboard: {"flaws": ["c322fffb-b7ef-400f-9ecd-5...
Depends On:
Blocks: CVE-2026-81665
TreeView+ depends on / blocked
 
Reported: 2026-09-04 08:48 UTC by lcelant
Modified: 2026-09-11 01:27 UTC (History)
3 users (show)

Fixed In Version: corosync-3.1.10-6.fc44 corosync-3.1.10-3.fc43
Clone Of:
Environment:
Last Closed: 2026-09-08 01:12:05 UTC
Type: ---
Embargoed:


Attachments (Terms of Use)

Description lcelant 2026-09-04 08:48:06 UTC
Disclaimer: Community trackers are created by Red Hat Product Security team on a best effort basis. Package maintainers are required to ascertain if the flaw indeed affects their package, before starting the update process.

Corosync is a group communication system providing reliable ordered messaging and membership services, and is the communication layer underlying Pacemaker HA clusters (RHEL High Availability Add-On). In exec/totempg.c, the totempg_deliver_fn function reassembles fragmented multicast messages into a fixed-size per-node assembly buffer (struct assembly, data[MESSAGE_SIZE_MAX + KNET_MAX_PACKET_SIZE], ~1.06 MB on normal builds, ~128 KB on small-memory-footprint builds). The only bounds check before the memcpy at line 663 is an assert() at line 662, which is compiled out in release builds (-DNDEBUG). assembly->index grows unboundedly at line 737 for each continuation fragment with no upper-bound check. After 17-18 fragments on normal builds (3 fragments on small-memory-footprint builds), the memcpy writes attacker-controlled data past the end of the heap buffer.

Verified via an ASan-instrumented standalone harness reproducing the exact buffer layout and memcpy/index logic: after 17 fragments of 65,481 bytes each, assembly->index reached 1,113,177 (buffer capacity 1,114,112); fragment 18 triggered a confirmed heap-buffer-overflow WRITE of 65,481 bytes, 64,546 bytes past the buffer end.

Present in corosync v3.1.10 (latest upstream release) and main HEAD (commit 65235a8); no upstream fix exists for this bug. Reported by Tristan Madani (Talence Security) via PSIRTSUPT-22352.

Comment 1 Fedora Update System 2026-09-04 09:48:39 UTC
FEDORA-2026-ef5ca6ecf7 (corosync-3.1.10-8.fc45) has been submitted as an update to Fedora 45.
https://bodhi.fedoraproject.org/updates/FEDORA-2026-ef5ca6ecf7

Comment 2 Fedora Update System 2026-09-04 09:51:03 UTC
FEDORA-2026-e97124c200 (corosync-3.1.10-6.fc44) has been submitted as an update to Fedora 44.
https://bodhi.fedoraproject.org/updates/FEDORA-2026-e97124c200

Comment 3 Fedora Update System 2026-09-04 09:54:42 UTC
FEDORA-2026-c0427570d6 (corosync-3.1.10-3.fc43) has been submitted as an update to Fedora 43.
https://bodhi.fedoraproject.org/updates/FEDORA-2026-c0427570d6

Comment 4 Fedora Update System 2026-09-05 01:34:51 UTC
FEDORA-2026-e97124c200 has been pushed to the Fedora 44 testing repository.
Soon you'll be able to install the update with the following command:
`sudo dnf upgrade --enablerepo=updates-testing --refresh --advisory=FEDORA-2026-e97124c200`
You can provide feedback for this update here: https://bodhi.fedoraproject.org/updates/FEDORA-2026-e97124c200

See also https://fedoraproject.org/wiki/QA:Updates_Testing for more information on how to test updates.

Comment 5 Fedora Update System 2026-09-05 01:57:53 UTC
FEDORA-2026-c0427570d6 has been pushed to the Fedora 43 testing repository.
Soon you'll be able to install the update with the following command:
`sudo dnf upgrade --enablerepo=updates-testing --refresh --advisory=FEDORA-2026-c0427570d6`
You can provide feedback for this update here: https://bodhi.fedoraproject.org/updates/FEDORA-2026-c0427570d6

See also https://fedoraproject.org/wiki/QA:Updates_Testing for more information on how to test updates.

Comment 6 Fedora Update System 2026-09-05 02:16:23 UTC
FEDORA-2026-ef5ca6ecf7 has been pushed to the Fedora 45 testing repository.
Soon you'll be able to install the update with the following command:
`sudo dnf upgrade --enablerepo=updates-testing --refresh --advisory=FEDORA-2026-ef5ca6ecf7`
You can provide feedback for this update here: https://bodhi.fedoraproject.org/updates/FEDORA-2026-ef5ca6ecf7

See also https://fedoraproject.org/wiki/QA:Updates_Testing for more information on how to test updates.

Comment 7 Fedora Update System 2026-09-08 01:12:05 UTC
FEDORA-2026-e97124c200 (corosync-3.1.10-6.fc44) has been pushed to the Fedora 44 stable repository.
If problem still persists, please make note of it in this bug report.

Comment 8 Fedora Update System 2026-09-11 01:27:04 UTC
FEDORA-2026-c0427570d6 (corosync-3.1.10-3.fc43) has been pushed to the Fedora 43 stable repository.
If problem still persists, please make note of it in this bug report.


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