Qubes OS Community • Secure Computing

includes malicious HVM qubes with memory balancing enabled, as well as templates and standalones that use in-qube kernels and that have memory balancing enabled. The default Qubes OS configuration is not affected, nor are commonly-used HVM qubes like Windows, since they don't have memory balancing enabled. Patching --------- The following packages contain security updates that address the vulnerabilities described in this bulletin: For Qubes 4.3, in dom0: - Xen packages, version 4.19.5-2 These packages will migrate from the security-testing repository to the current (stable) repository over the next two weeks after being tested by the community. [2] Once available, the packages should be installed via the Qubes Update tool or its command-line equivalents. [1] Dom0 must be restarted afterward in order for the updates to take effect. If you use Anti Evil Maid, you will need to reseal your secret passphrase to new PCR values, as PCR18+19 will change due to the new Xen binaries. Credits -------- See the original Xen Security Advisories. [3][4][5][6] References ----------- [1] https://doc.qubes-os.org/en/latest/user/how-to-guides/how-to-update.html [2] https://doc.qubes-os.org/en/latest/user/downloading-installing-upgrading/testing.html [3] https://xenbits.xen.org/xsa/advisory-500.html [4] https://xenbits.xen.org/xsa/advisory-505.html [5] https://xenbits.xen.org/xsa/advisory-506.html [6] https://xenbits.xen.org/xsa/advisory-507.html [7] A PV qube is a qube that is running with virt_mode set to "pv." [8] For each qube that is running with virt_mode set to "hvm," there's a small Xen-internal helper VM running alongside it, in which QEMU is executed to provide device emulation for that qube. This helper VM runs in PV mode and is called a "stubdomain." -- The Qubes Security Team https://www.qubes-os.org/security/ Source: qsb-116-2026.txt (https://github.com/QubesOS/qubes-secpack/blob/f9001423ffb11de26bdcf0b4478838739cc3f6b3/QSBs/qsb-116-2026.txt) Marek Marczykowski-Górecki (https://www.qubes-os.org/team/#marek-marczykowski-g%C3%B3recki)’s PGP signature -----BEGIN PGP SIGNATURE----- iQIzBAABCAAdFiEELRdx/k12ftx2sIn61lWk8hgw4GoFAmpoeyMACgkQ1lWk8hgw 4GqUjw//brO4x3oOygOpewPqcjgYqohh4qPu5Dpm6JBvtxiIZQWEv9UZg0RqfMVc omoalUCQhoTPu8QYnXu3HKo87LGcrUKKf2KeRx4CyT8LsZCQufA25uWD3Sr6eVsA 38Q/Znq3VyUpa5tMQm28JIIA9m2PMAMaXu5ElZVAw5kvcRncwRh8WDOrkVOO97ll gSfBo3SJ0OfSUDcQvGa8f5+4Jx/SPoJn5zLo3Ott4tT7Tz2NAfE2Xlxl7karasY/ vCY+Lo8ACN+0ShELslGKYZnNdwLuwkz3lVN+FqDbLrHauBUjDLH7+yTXJvO9ZoXq 3LTpHopzv8oSJJyhq0YeO4XlKt+USn2HbIMqhJ9ON8aHHVE3/YhVJume4RuxSlHx WAStN0bYH/NqSywYB3wWmGEho9wRw8bxLrOBIuZO3V63HpMJnCL412F7RFA2/9iS muq3Iix9YpqfI/Q1Q18JSnYYLlWaphMtc/OJki5FAzp1B5DtQtPcQtg/vcy9tsrX P9zrK4j3Dj/vPzZd6DwDmTBPxuiLQX79TQojl7NClVatkULfdHQGDKogfPmsJng9 IpKMBkMZ85QVv+DG/XFtXpynBdeg/6eTeWiexC7WF3HgILkhy2RadQz0eHsEwCmp fIeVYQ2Es3eVH7aNaPHwaAcklNP+7yppgw5O81PGOlbD3Z9a15Y= =vPOZ -----END PGP SIGNATURE----- Source: qsb-116-2026.txt.sig.marmarek (https://github.com/QubesOS/qubes-secpack/blob/f9001423ffb11de26bdcf0b4478838739cc3f6b3/QSBs/qsb-116-2026.txt.sig.marmarek) Simon Gaiser (aka HW42) (https://www.qubes-os.org/team/#simon-gaiser-aka-hw42)’s PGP signature -----BEGIN PGP SIGNATURE----- iQIzBAABCgAdFiEE6hjn8EDEHdrv6aoPSsGN4REuFJAFAmpoh00ACgkQSsGN4REu FJCSVhAApAdVntLjACF7SJ9h7SF4M1IiDKKUQRnUhwEa06d/qDjFg/aVlsL6LghW +cKpPdjSDWwGPhAsJhbxTeiSSAkX300qJuqX3/K0h6iw7jaQkqb6kmwaAhK7J8Ym 9F5LvcP8Vvx3G0Gi4YogNzrwA+AMlfCgKLgp7MsHKumE1TY0pp5dI6DMqz2/EasV ODrppsfXkMMmES5aR8C6Pxe51pfBbXVqVmffjYxaz/C9VvcfGbHja8OdnOuNeqmo yzR2pP6BGdIl2KGfq1GzuuYWtitIcrG8aEnYfcmhiHbHkTIObNwHo7MOwBT2Q9H4 ALJfuBfC1ChBvmmzRIPgOzPbiz0MLIWcjFvKRmXW8azTTQOyRQQbG5lDGeu+aJm0 ZRdyXPQh2294MmmL3r+xtyFJTFw5WABdxjZa10nlB5B5JQ8FrV7koNc4quXhCS4U ceAwpvCuRKTX1Lg+NDaPFtxAmYX98QkLT09V34vyqksOcMR+DY7stHol8T+hYIMM 8DXZDBdndUMkU/DU5xfj4Z/wtgkB66eLKBypxqibiPx33vkBZOIAYtNYK7zFnrTk HnrHAGpm0sLlNdLzNA4XQ7yMTdDwzxW6GeYacYWxDT3t9Qc9vroGVju3CExQtljs

4znS5FAHrlPSv4xi7aWiypVwB/MsMbrdNcd0/g9px6RbszpNGpA= =BjeB -----END PGP SIGNATURE----- Source: qsb-116-2026.txt.sig.simon (https://github.com/QubesOS/qubes-secpack/blob/f9001423ffb11de26bdcf0b4478838739cc3f6b3/QSBs/qsb-116-2026.txt.sig.simon) What is the purpose of this announcement? The purpose of this announcement is to inform the Qubes community that a new Qubes security bulletin (QSB) has been published. What is a Qubes security bulletin (QSB)? A Qubes security bulletin (QSB) (https://www.qubes-os.org/security/qsb/) is a security announcement issued by the Qubes security team (https://doc.qubes-os.org/en/latest/project-security/security.html#qubes-security-team). A QSB typically provides a summary and impact analysis of one or more recently-discovered software vulnerabilities, including details about patching to address them. Why should I care about QSBs? QSBs tell you what actions you must take in order to protect yourself from recently-discovered security vulnerabilities. In most cases, security vulnerabilities are addressed by updating normally (https://doc.qubes-os.org/en/latest/user/how-to-guides/how-to-update.html). However, in some cases, special user action is required. In all cases, the required actions are detailed in QSBs. What are the PGP signatures that accompany QSBs? A PGP (https://en.wikipedia.org/wiki/Pretty_Good_Privacy) signature is a cryptographic digital signature (https://en.wikipedia.org/wiki/Digital_signature) made in accordance with the OpenPGP (https://en.wikipedia.org/wiki/Pretty_Good_Privacy#OpenPGP) standard. PGP signatures can be cryptographically verified with programs like GNU Privacy Guard (GPG) (https://gnupg.org/). The Qubes security team cryptographically signs all QSBs so that Qubes users have a reliable way to check whether QSBs are genuine. The only way to be certain that a QSB is authentic is by verifying its PGP signatures. Why should I care whether a QSB is authentic? A forged QSB could deceive you into taking actions that adversely affect the security of your Qubes OS system, such as installing malware or making configuration changes that render your system vulnerable to attack. Falsified QSBs could sow fear, uncertainty, and doubt about the security of Qubes OS or the status of the Qubes OS Project. How do I verify the PGP signatures on a QSB? The following command-line instructions assume a Linux system with git and gpg installed. (For Windows and Mac options, see OpenPGP software (https://doc.qubes-os.org/en/latest/project-security/verifying-signatures.html#openpgp-software).) Obtain the Qubes Master Signing Key (QMSK), e.g.: $ gpg --fetch-keys https://keys.qubes-os.org/keys/qubes-master-signing-key.asc gpg: directory '/home/user/.gnupg' created gpg: keybox '/home/user/.gnupg/pubring.kbx' created gpg: requesting key from 'https://keys.qubes-os.org/keys/qubes-master-signing-key.asc' gpg: /home/user/.gnupg/trustdb.gpg: trustdb created gpg: key DDFA1A3E36879494: public key "Qubes Master Signing Key" imported gpg: Total number processed: 1 gpg: imported: 1 (For more ways to obtain the QMSK, see How to import and authenticate the Qubes Master Signing Key (https://doc.qubes-os.org/en/latest/project-security/verifying-signatures.html#how-to-import-and-authenticate-the-qubes-master-signing-key).) View the fingerprint of the PGP key you just imported. (Note: gpg> indicates a prompt inside of the GnuPG program. Type what appears after it when prompted.) $ gpg --edit-key 0x427F11FD0FAA4B080123F01CDDFA1A3E36879494 gpg (GnuPG) 2.2.27; Copyright (C) 2021 Free Software Foundation, Inc. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. pub rsa4096/DDFA1A3E36879494 created: 2010-04-01 expires: never usage: SC trust: unknown validity: unknown [ unknown] (1). Qubes Master Signing Key gpg> fpr

pub rsa4096/DDFA1A3E36879494 2010-04-01 Qubes Master Signing Key Primary key fingerprint: 427F 11FD 0FAA 4B08 0123 F01C DDFA 1A3E 3687 9494 Important: At this point, you still don’t know whether the key you just imported is the genuine QMSK or a forgery. In order for this entire procedure to provide meaningful security benefits, you must authenticate the QMSK out-of-band. Do not skip this step! The standard method is to obtain the QMSK fingerprint from multiple independent sources in several different ways and check to see whether they match the key you just imported. For more information, see How to import and authenticate the Qubes Master Signing Key (https://doc.qubes-os.org/en/latest/project-security/verifying-signatures.html#how-to-import-and-authenticate-the-qubes-master-signing-key). Tip: After you have authenticated the QMSK out-of-band to your satisfaction, record the QMSK fingerprint in a safe place (or several) so that you don’t have to repeat this step in the future. Once you are satisfied that you have the genuine QMSK, set its trust level to 5 (“ultimate”), then quit GnuPG with q. gpg> trust pub rsa4096/DDFA1A3E36879494 created: 2010-04-01 expires: never usage: SC trust: unknown validity: unknown [ unknown] (1). Qubes Master Signing Key Please decide how far you trust this user to correctly verify other users' keys (by looking at passports, checking fingerprints from different sources, etc.) 1 = I don't know or won't say 2 = I do NOT trust 3 = I trust marginally 4 = I trust fully 5 = I trust ultimately m = back to the main menu Your decision? 5 Do you really want to set this key to ultimate trust? (y/N) y pub rsa4096/DDFA1A3E36879494 created: 2010-04-01 expires: never usage: SC trust: ultimate validity: unknown [ unknown] (1). Qubes Master Signing Key Please note that the shown key validity is not necessarily correct unless you restart the program. gpg> q Use Git to clone the qubes-secpack repo. $ git clone https://github.com/QubesOS/qubes-secpack.git Cloning into 'qubes-secpack'... remote: Enumerating objects: 4065, done. remote: Counting objects: 100% (1474/1474), done. remote: Compressing objects: 100% (742/742), done. remote: Total 4065 (delta 743), reused 1413 (delta 731), pack-reused 2591 Receiving objects: 100% (4065/4065), 1.64 MiB | 2.53 MiB/s, done. Resolving deltas: 100% (1910/1910), done. Import the included PGP keys. (See our PGP key policies (https://doc.qubes-os.org/en/latest/project-security/security-pack.html#pgp-key-policies) for important information about these keys.) $ gpg --import qubes-secpack/keys/*/* gpg: key 063938BA42CFA724: public key "Marek Marczykowski-Górecki (Qubes OS signing key)" imported gpg: qubes-secpack/keys/core-devs/retired: read error: Is a directory gpg: no valid OpenPGP data found. gpg: key 8C05216CE09C093C: 1 signature not checked due to a missing key gpg: key 8C05216CE09C093C: public key "HW42 (Qubes Signing Key)" imported gpg: key DA0434BC706E1FCF: public key "Simon Gaiser (Qubes OS signing key)" imported gpg: key 8CE137352A019A17: 2 signatures not checked due to missing keys gpg: key 8CE137352A019A17: public key "Andrew David Wong (Qubes Documentation Signing Key)" imported gpg: key AAA743B42FBC07A9: public key "Brennan Novak (Qubes Website & Documentation Signing)" imported gpg: key B6A0BB95CA74A5C3: public key "Joanna Rutkowska (Qubes Documentation Signing Key)" imported gpg: key F32894BE9684938A: public key "Marek Marczykowski-Górecki (Qubes Documentation Signing Key)" imported gpg: key 6E7A27B909DAFB92: public key "Hakisho Nukama (Qubes Documentation Signing Key)" imported gpg: key 485C7504F27D0A72: 1 signature not checked due to a missing key gpg: key 485C7504F27D0A72: public key "Sven Semmler (Qubes Documentation Signing Key)" imported