Qubes OS

[7] https://www.intel.com/content/www/us/en/security-center/advisory/intel-sa-01441.html [8] https://www.intel.com/content/www/us/en/security-center/advisory/intel-sa-01442.html [9] https://github.com/intel/Intel-Linux-Processor-Microcode-Data-Files/blob/main/releasenote.md#microcode-20260812 -- The Qubes Security Team https://www.qubes-os.org/security/ Source: qsb-117-2026.txt (https://github.com/QubesOS/qubes-secpack/blob/2fae4b5eb43fae0b3bd58cc50444aac283d702fb/QSBs/qsb-117-2026.txt) Marek Marczykowski-Górecki (https://www.qubes-os.org/team/#marek-marczykowski-g%C3%B3recki)’s PGP signature -----BEGIN PGP SIGNATURE----- iQIzBAABCAAdFiEELRdx/k12ftx2sIn61lWk8hgw4GoFAmqSEC8ACgkQ1lWk8hgw 4Go3Xw/+LdLu3Dx+S1iH8YDpk2Ef2WJwXNl+Msmt+cTntk/wdEvsAeRWc0/t85fZ ySfiYIAq+PvED2G7rSbVmgqWp3sPNCaSS89Penr3praoLfxRxLc23HbLQrabnKgK 2TNRiFlk+OSqvjqvItn/y+kyxB4TZAnNtDHu9Eins/B0gVAz+P//aSFVOb42UTo9 7gLNWpW1CxflQqKfNnEqxah5m2iH72pMzir6F8fXC9JFMp1PWcvn1cRfKHrAs3lw qw7kUz2mByT1qHIMs/iQ6PA4bOhlo0km1M+z+sFhyXNvsdz2JlAnlViX7ZOCCxrb YoJd/VPnaH9xtUUh++iDmtIyylxTlx7vmOb/WEefucD+EH7zM5x3BdKb7M0vpKgy vJU3a5+pY90opla7hT8GWVuIpzhBSLQlhR4RNLWSdu+pQeWqUPG2rapww0B3/Hia t98H76iMMCDvy74Bj+hChrO95wgY35JJveSXF51WiJmOjofxFeyxgTBrlcjlmpkb kUybNm8fm9LZAOG6zFJIYJN0q0+tKu0qc4Z1cU+EIIL6G5msMUIMKXV3Tg/KpUW/ Yo3dGYUUTVCsmKtaXw9ASRvnaHS3ADC6wRZK5XSkqsXNVoQI0sWkik5vn0VvS+LW VdOSWdoQGJRAAEpRmM/grsxgqq3Sn+Tck2g3IcgK+aRysClb6z8= =Xehb -----END PGP SIGNATURE----- Source: qsb-117-2026.txt.sig.marmarek (https://github.com/QubesOS/qubes-secpack/blob/2fae4b5eb43fae0b3bd58cc50444aac283d702fb/QSBs/qsb-117-2026.txt.sig.marmarek) Simon Gaiser (aka HW42) (https://www.qubes-os.org/team/#simon-gaiser-aka-hw42)’s PGP signature -----BEGIN PGP SIGNATURE----- iQIzBAABCgAdFiEE6hjn8EDEHdrv6aoPSsGN4REuFJAFAmqSEywACgkQSsGN4REu FJDCww//aucPqi/Fujn0/aVD2zSwNw9+b+8KulNRODaP86MaNu9kUs6+TNIOvGOx egeJim/vCIbdehCzd2x1+GKonmtlQzHTFE3VKCJXQ7u74/fa2cSIZwmjjwdjhbgs 78m4grmdsW4UtQGBEku6M4Nl4vYDjbw3orCwONf4rqOG8dsHK0REJnBnXTeq6aAo Q/3NfuE5b

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

QSB-118: Dom0 arbitrary code execution in qvm-copy-to-vm error reporting https://www.qubes-os.org/news/2026/08/29/qsb-118/ We have published Qubes Security Bulletin (QSB) 118: Dom0 arbitrary code execution in qvm-copy-to-vm error reporting (https://github.com/QubesOS/qubes-secpack/blob/f65082c8211a421ed15a59219d6e54e93289fafb/QSBs/qsb-118-2026.txt). The text of this QSB and its accompanying cryptographic signatures are reproduced below, followed by a general explanation of this announcement and authentication instructions. Qubes Security Bulletin 118 ---===[ Qubes Security Bulletin 118 ]===--- 2026-08-28 Dom0 arbitrary code execution in qvm-copy-to-vm error reporting User action ------------ Continue to update normally [1] in order to receive the security updates described in the "Patching" section below. No other user action is required in response to this QSB. Summary -------- If `qvm-copy-to-vm` is used to copy a file from dom0 to a malicious qube, that qube can inject an arbitrary command into dom0. Impact ------- If an attacker has compromised a qube, and if the user initiates a `qvm-copy-to-vm` call from dom0 to the compromised qube, then the attacker can exploit this vulnerability in order to inject an arbitrary command into dom0, which allows the attacker to take control of Qubes OS. Technical details ------------------ The `qvm-copy-to-vm` tool allows copying files from dom0 to a specified qube. It uses the "qfile" protocol, which is a simplified archive format, including simple file metadata (much simpler than `tar` or `cpio`). The protocol also includes transfer confirmation at the end, which is sent by the target back to the source. This confirmation includes a checksum of all the transferred files, an error code (if any), and the name of the last received file. In the case of an error, as reported by the error code field, dom0 displays a GUI message that includes the error information and the

27 program_invocation_short_name, buf, strerror(errno)) < 0) { 28 fprintf(stderr, "Failed to allocate memory for error message :(\n"); 29 return; 30 } 31 #undef KDIALOG_CMD 32 #undef ZENITY_CMD 33 fprintf(stderr, "%s\n", buf); 34 system(dialog_cmd); 35 } 36 37 _Noreturn void gui_fatal(const char *fmt, ...) { 38 va_list args; 39 va_start(args, fmt); 40 display_error(fmt, args); 41 va_end(args); 42 exit(1); 43 } The problem is that `sanitize_remote_filename()` removes only non-ASCII characters (and double quotation marks) but leaves shell meta-characters in place. Then, `system()` runs the constructed command, including the attacker-controlled name via the shell. Note that the VM variant of `qvm-copy-to-vm` is not affected, as its version of the error reporting function does not use `system()`: core-agent-linux/qubes-rpc/gui-fatal.c: 16 static void produce_message(const char *type, const char *fmt, va_list args) 17 { ... 31 if (progress_type && !strcmp(progress_type, "gui")) 32 { 33 switch (fork()) 34 { 35 case -1: 36 exit(1); // what else 37 case 0: 38 if (geteuid() == 0) { 39 if (setuid(getuid()) != 0) { 40 perror("setuid failed, not calling zenity/kdialog"); 41 exit(1); 42 } 43 } 44 fix_display(); 45 execlp("/usr/bin/zenity", "zenity", "--error", "--text", dialog_msg, NULL); 46 execlp("/usr/bin/kdialog", "kdialog", "--sorry", dialog_msg, NULL); 47 exit(1); 48 default:; 49 } 50 } 51 free(dialog_msg); 52 } 53 54 void gui_fatal(const char *fmt, ...) 55 { 56 va_l

corresponding qubes-secpack.git repo tags. [2] [2] Don't just trust the contents of this file blindly! Verify the digital signatures! Instructions for doing so are documented here: https://doc.qubes-os.org/en/latest/project-security/security-pack.html -- The Qubes Security Team https://www.qubes-os.org/security/ Source: canary-048-2026.txt (https://github.com/QubesOS/qubes-secpack/blob/f1378920daaaad3e338fa18aa972da074bc45aef/canaries/canary-048-2026.txt) Marek Marczykowski-Górecki (https://www.qubes-os.org/team/#marek-marczykowski-g%C3%B3recki)’s PGP signature -----BEGIN PGP SIGNATURE----- iQIzBAABCAAdFiEELRdx/k12ftx2sIn61lWk8hgw4GoFAmqhJaEACgkQ1lWk8hgw 4GpAUA//dvesbc30xLrZ5hRrJgPBBOaMIXjLZk2il/EljKLAMLdPOk5Y01kNLLGS nvnLU0M5U8y1Oqlfj7WybABht8SrPSBg9gI1CrRvA69urz5V6VHDUsqAMhXozdLK FgT4+SuQfiAvlXOdjPljcZO4jWXWcQMWjecYTTiQdnMNC90VkrncYjNeioh6rhaL oCim2t5ynb9wpyo7zzG9KNDtDUzPSAphSZoJhb3PJXNOxHV6RLsyoz9b1wa1c3xp IJdS1EzMf/1/bmlZwg9FnLcGVOO/TdyOSKxP4d54SVt/JmYfpk2qAVfn/NWjlzVc LqcwebzGHQ56A4kyvc04PEuMzryneYDmxboKtwKUnOyMdnOxHtpbqh/jX6T/GodA wO8oJdoT5l1ugLfFK/sGluSx6FnFoczgukFxk+cIn3l38mEUAQLshWRNL3gk8LkW cKTFBBntwlV2XfmJBFhOM4s6N74RTrNhxWlsgT4LyOCcFRIT8CCLicmvmxSgjWJo v3p+pKqLNFe0GU64KUlt3Fvc0m4hyvxPZbmzA/UOevMzssX5BHkRXQDJaknLppy+ yZp/gfBX575wlgWn+khXPYQSIcHyEuZifZoMaGnfU0OgjPMcmC4SY9xQf2cH/dN+ gTyhd0+s9RfyWDdA2l1ZvG10t1Pz5SIJecPXHFMk+F6qHEpjezI= =wcFj -----END PGP SIGNATURE----- Source: canary-048-2026.txt.sig.marmarek (https://github.com/QubesOS/qubes-secpack/blob/f1378920daaaad3e338fa18aa972da074bc45aef/canaries/canary-048-2026.txt.sig.marmarek) Simon Gaiser (aka HW42) (https://www.qubes-os.org/team/#simon-gaiser-aka-hw42)’s PGP signature -----BEGIN PGP SIGNATURE----- iQIzBAABCgAdFiEE6hjn8EDEHdrv6aoPSsGN4REuFJAFAmqhK+QACgkQSsGN4REu FJCzHQ//ejKjw9KcCp8EKE/pMMSeCHmIOBDqZFsM0Ifo4rzyCVc2TqLZ6K0JviuQ 5otz/lor5rI4Z1wCR4fZO7YwWHewaX7w7yILp6tRV+9el22lhWPJMl7BavjBK92d 8WUiuab0DrlxROUDtm62mgzQ5dHcqQjj/bZZhSeq/69e/L3OJsWclOdAOt+LjSUa rXYD+bB23PZh3FGdvW0znTLbs/0XpH

part of the file name in most cases. And even when they do control the full path, many users would likely find such a path suspicious, which would likely make it more difficult for an attacker to successfully trick the user into opening such a path. Discussion ----------- Normally, we do not issue Qubes security bulletins for purely "in-VM" vulnerabilities (like this one) that do not involve crossing the VM security boundary. However, we have decided to make an exception in this case, since this is a bug in our code and since qvm-open-in-vm is specifically intended to operate on untrusted input. While qvm-open-in-vm is designed to be hardened, keep in mind that handling less trusted data in a more trusted VM still can be risky for other reasons, for example: - Unsafe handling of attacker-controlled paths is an easy mistake to make in the shell. - A file explorer could render the thumbnail of an untrusted file with a buggy parser. - You might accidentally open the file with an application other than qvm-open-in-vm, exposing the full attack surface of that application. Patching --------- The following package contains the security update that addresses the vulnerability described in this bulletin: For Qubes 4.3, in affected templates and standalones: - qubes-core-agent version 4.3.48 This package 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 package should be installed via the Qubes Update tool or its command-line equivalents. [1] In order for this security update to take effect, all affected templates must be updated with the package above, then shut down. Afterward, all qubes based on these templates (including disposables) must be restarted. All affected standalones must be updated with the package above. Credits -------- This vulnerability was first reported by Giulio Berra. Shortly after, it was independently repor

The FPF is a long-standing Qubes Partner (https://www.qubes-os.org/partners/). As a nonprofit organization, it is dedicated to supporting and defending public interest journalism. It leads the development of SecureDrop (https://securedrop.org/), an open-source whistleblower submission platform used by more than 50 media organizations around the world to securely accept documents from anonymous sources. FPF uses Qubes OS in the development of an integrated SecureDrop Workstation (https://github.com/freedomofpress/securedrop-workstation).