Description
The fixes for XSA-422 (Branch Type Confusion) and XSA-434 (Speculative
Return Stack Overflow) are not IRQ-safe. It was believed that the
mitigations always operated in contexts with IRQs disabled.
However, the original XSA-254 fix for Meltdown (XPTI) deliberately left
interrupts enabled on two entry paths; one unconditionally, and one
conditionally on whether XPTI was active.
As BTC/SRSO and Meltdown affect different CPU vendors, the mitigations
are not active together by default. Therefore, there is a race
condition whereby a malicious PV guest can bypass BTC/SRSO protections
and launch a BTC/SRSO attack against Xen.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| Xen | Xen | — | — |
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 | xen | 4.17.2+76-ge1f9cb16e2-1 | — |
| Debian 13 | xen | 4.17.2+76-ge1f9cb16e2-1 | — |
| Debian 12 | xen | 4.17.2+76-ge1f9cb16e2-1~deb12u1 | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 26.10 | xen | No fix yet | — |
| Ubuntu 26.04 LTS | xen | No fix yet | — |
| Ubuntu 25.10 | xen | No fix yet | — |
| Ubuntu 24.04 LTS | xen | No fix yet | — |
| Ubuntu 22.04 LTS | xen | No fix yet | — |
Show 3 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 20.04 LTS | xen | No fix yet | — |
| Ubuntu 18.04 LTS | xen | No fix yet | — |
| Ubuntu 16.04 LTS | xen | No fix yet | — |
SUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES 15 SP5 | xen | 4.17.2_08-150500.3.15.1 | SUSE-SU-2023:4945-1, SUSE-SU-2023:4475-1 |
| SLES 15 SP4 | xen | 4.16.5_08-150400.4.40.1 | SUSE-SU-2023:4476-1 |
| SLES 15 SP3 | xen | 4.14.6_08-150300.3.60.1 | SUSE-SU-2023:4466-1 |
| SLES 15 SP2 | xen | 4.13.5_08-150200.3.83.1 | SUSE-SU-2023:4484-1 |
| SLES 15 SP1 | xen | 4.12.4_42-150100.3.98.1 | SUSE-SU-2023:4485-1 |
Show 14 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES 12 SP5 | xen | 4.12.4_42-3.100.1 | SUSE-SU-2023:4486-1 |
| SLES for SAP 15 SP3 | xen | 4.14.6_08-150300.3.60.1 | SUSE-SU-2023:4466-1 |
| SLES for SAP 15 SP2 | xen | 4.13.5_08-150200.3.83.1 | SUSE-SU-2023:4484-1 |
| SLES for SAP 15 SP1 | xen | 4.12.4_42-150100.3.98.1 | SUSE-SU-2023:4485-1 |
| SLES for SAP 12 SP5 | xen | 4.12.4_42-3.100.1 | SUSE-SU-2023:4486-1 |
| SLE Micro 5.5 | xen | 4.17.2_08-150500.3.15.1 | SUSE-SU-2023:4945-1, SUSE-SU-2023:4475-1 |
| SLE Micro 5.4 | xen | 4.16.5_08-150400.4.40.1 | SUSE-SU-2023:4476-1 |
| SLE Micro 5.3 | xen | 4.16.5_08-150400.4.40.1 | SUSE-SU-2023:4476-1 |
| SLE Micro 5.2 | xen | 4.14.6_08-150300.3.60.1 | SUSE-SU-2023:4466-1 |
| SLE Micro 5.1 | xen | 4.14.6_08-150300.3.60.1 | SUSE-SU-2023:4466-1 |
| SLE HPC 15 SP3 | xen | 4.14.6_08-150300.3.60.1 | SUSE-SU-2023:4466-1 |
| SLE HPC 15 SP2 | xen | 4.13.5_08-150200.3.83.1 | SUSE-SU-2023:4484-1 |
| SLE HPC 15 SP1 | xen | 4.12.4_42-150100.3.98.1 | SUSE-SU-2023:4485-1 |
| SUSE Enterprise Storage 7.1 | xen | 4.14.6_08-150300.3.60.1 | SUSE-SU-2023:4466-1 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | xen | 4.18.0_02-1.1 | openSUSE-SU-2024:13442-1 |
| openSUSE Leap 15.5 | xen | 4.17.2_08-150500.3.15.1 | SUSE-SU-2023:4945-1, SUSE-SU-2023:4475-1 |
| openSUSE Leap 15.4 | xen | 4.16.5_08-150400.4.40.1 | SUSE-SU-2023:4476-1 |
Show 2 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Leap Micro 5.4 | xen | 4.16.5_08-150400.4.40.1 | SUSE-SU-2023:4476-1 |
| openSUSE Leap Micro 5.3 | xen | 4.16.5_08-150400.4.40.1 | SUSE-SU-2023:4476-1 |
Alpine
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine v3.24 | xen | 4.17.2-r4 | — |
| Alpine v3.23 | xen | 4.17.2-r4 | — |
| Alpine v3.22 | xen | 4.17.2-r4 | — |
| Alpine v3.21 | xen | 4.17.2-r4 | — |
| Alpine v3.20 | xen | 4.17.2-r4 | — |
Show 5 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine v3.19 | xen | 4.17.2-r4 | — |
| Alpine v3.18 | xen | 4.17.2-r4 | — |
| Alpine v3.17 | xen | 4.16.5-r4 | — |
| Alpine v3.16 | xen | 4.16.5-r4 | — |
| Alpine v3.15 | xen | 4.15.5-r3 | — |
Advisories 9
- SUSE-SU-2023:4484-1 Security update for xen SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2023:4485-1 Security update for xen SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2023:4486-1 Security update for xen SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2023:4466-1 Security update for xen SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2023:4945-1 Security update for xen SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2023:4476-1 Security update for xen SUSE / openSUSE Security Updates · Feb 4, 2026
- openSUSE-SU-2024:13442-1 xen-4.18.0_02-1.1 on GA media SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2023:4475-1 Security update for xen SUSE / openSUSE Security Updates · Feb 4, 2026
- WID-SEC-2023-2900 Xen: Mehrere Schwachstellen ermöglichen Offenlegung von Informationen BSI CERT-Bund (WID) · Sep 22, 2024