Description
Issue summary: A malicious remote peer may flood the local QUIC
stack with NEW_CONNECTION_ID frames by avoiding a limit check on
how many connection IDs the remote QUIC stack can use.
Impact summary: The local QUIC stack sends a RETIRE_CONN_ID frame
for every NEW_CONNECTION_ID frame it receives. The RETIRE_CONN_ID
frame is dispatched via the Control Frame Queue (CFQ). If the remote
peer also withholds ACKs, then it can force the local stack
to allocate ~400MB (depending on ACK delay).
CWE: CWE-770: Allocation of Resources Without Limits or Throttling
Description: RFC 9000 sections 5.1.1 and 5.1.2 [1] describe the mechanism
by which a remote peer can notify the local QUIC stack to change the
destination connection ID (a.k.a. CID) the local stack uses to
identify the connection at the remote peer. Each CID is associated
with a sequence number. The sequence number is transmitted
in NEW_CONNECTION_ID and RETIRE_CONNECTION_ID frames to identify the CID
which is being either associated with a connection or retired.
The remote peer sends a NEW_CONNECTION_ID frame to let the local stack know
a new CID is being associated with an existing connection. The
NEW_CONNECTION_ID frame carries the new CID, its sequence number, and the
retire-prior-to number. The retire-prior-to identifies existing
CIDs that are to be retired. The local QUIC stack must send a
RETIRE_CONNECTION_ID for every destination CID whose sequence number
is less than retire-prior-to. The CID becomes retired after the
local stack receives an ACK for its RETIRE_CONNECTION_ID frame.
Although the OpenSSL QUIC stack supports at most one destination CID
for every connection, it can be tricked into processing more than
one RETIRE_CONNECTION_ID frame per connection. The OpenSSL QUIC
stack currently retires the destination CID as soon as it receives
the NEW_CONNECTION_ID, while in fact the destination CID must
be retired after an ACK for the RETIRE_CONNECTION_ID frame is received.
Correcting the flawed logic also fixes the backlog growth.
[1] https://datatracker.ietf.org/doc/html/rfc9000#name-issuing-connection-ids
FIPS impact: no
The FIPS module is not affected as the QUIC implementation is outside of
the OpenSSL FIPS module boundary.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| OpenSSL | OpenSSL | 4.0.0 – < 4.0.3, 3.6.0 – < 3.6.5, 3.5.0 – < 3.5.9, 3.4.0 – < 3.4.8 | 4.0.3 |
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | openssl | 3.6.5-1 | — |
| Debian 13 | openssl | 3.5.7-1~deb13u3 | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 26.10 | edk2 +1 | No fix yet | — |
| Ubuntu 26.04 LTS | edk2 +1 | No fix yet | — |
| Ubuntu 26.04 LTS | openssl | 3.5.5-1ubuntu3.6 | USN-8847-1 |
| Ubuntu 24.04 LTS | openssl | 3.0.13-0ubuntu3.16 | USN-8847-1 |
| Ubuntu 22.04 LTS | openssl | 3.0.2-0ubuntu1.30 | USN-8847-1 |
Show 1 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu Pro 22.04 LTS | nodejs | No fix yet | — |
Red Hat
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Red Hat Hardened Images 1 | openssl +10 | 3.5.9-0.1.hum1 | RHSA-2026:74166, RHSA-2026:74162 |
Rocky Linux
Errata ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Rocky Linux 10 | openssl +3 | 1:3.5.9-1.el10_3 | RLSA-2026:98588 |
| Rocky Linux 9 | openssl +3 | 1:3.5.9-1.el9_9 | RLSA-2026:98484 |
SUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES 15 SP7 | openssl-3 | 3.5.0-150700.5.53.2 | SUSE-SU-2026:4414-1 |
Show 3 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES for SAP 16.0 | openssl-3 | 3.5.0-160000.11.1 | SUSE-SU-2026:24245-1 |
| SLES 16.0 | openssl-3 | 3.5.0-160000.11.1 | SUSE-SU-2026:24245-1 |
| SLE Micro 6.2 | openssl-3 | 3.5.0-160000.11.1 | SUSE-SU-2026:24188-1 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Leap 16.0 | openssl-3 | 3.5.0-160000.11.1 | openSUSE-SU-2026:22102-1 |
Alpine
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine v3.21 | openssl | 3.3.7-r2 | — |
Amazon Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Amazon Linux 2023 | openssl +5 | 1:3.5.8-1.amzn2023.0.3 | ALAS2023-2026-3204 |
Azure Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Azure Linux 3 | openssl | 3.3.7-7 | — |
| Azure Linux 3 | rust +3 | No fix yet | — |
Wolfi
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Wolfi rolling | openssl-4.0 +2 | 4.0.3-r0 | — |
Advisories 11
- RLSA-2026:98588 Moderate: openssl security, bug fix, and enhancement update Rocky Linux Security Advisories · Nov 13, 2026
- RLSA-2026:98484 Moderate: openssl security, bug fix, and enhancement update Rocky Linux Security Advisories · Nov 13, 2026
- WID-SEC-2026-3638 OpenSSL: Mehrere Schwachstellen BSI CERT-Bund (WID) · Nov 12, 2026
- SUSE-SU-2026:24245-1 Security update for openssl-3 SUSE / openSUSE Security Updates · Oct 21, 2026
- SUSE-SU-2026:24188-1 Security update for openssl-3 SUSE / openSUSE Security Updates · Oct 20, 2026
- RHSA-2026:74162 Red Hat Security Advisory: Red Hat Hardened Images RPMs bug fix and enhancement update Red Hat Security Advisories (RHSA) · Oct 20, 2026
- RHSA-2026:74166 Red Hat Security Advisory: Red Hat Hardened Images RPMs bug fix and enhancement update Red Hat Security Advisories (RHSA) · Oct 20, 2026
- openSUSE-SU-2026:22102-1 Security update for openssl-3 SUSE / openSUSE Security Updates · Oct 19, 2026
- ALAS2023-2026-3204 Important: openssl security update (Amazon Linux 2023) Amazon Linux Security Center (ALAS) · Oct 12, 2026
- SUSE-SU-2026:4414-1 Security update for openssl-3 SUSE / openSUSE Security Updates · Oct 2, 2026
- USN-8847-1 openssl vulnerabilities Ubuntu Security Notices (USN) · Oct 2, 2026
References
- OpenSSL Advisory vendor-advisory
- 4.0.3 git commit patch
- 3.6.5 git commit patch
- 3.5.9 git commit patch
- 3.4.8 git commit patch