Hello oss-security!

Red Hat and OpenWrt [1] and Gentoo [2] are already aware, but maybe this matter is of interest to more of you:

It has come to my attention through [0] that xmlrpc-c bundles a (very old and) vulnerable copy of libexpat. I reached out to upstream and they made a few minor related changes:

- The configure script started to default to libxml2 rather than libexpat at [3].

- Also there is a new readme now [4] that warns that the bundled Expat is "unfit for use in a setting where the communication partner is not friendly" and a similar new note [5] in the main readme saying…

"When the Expat developer pointed out in 2025 the likelihood that the Xmlrpc-c fork of Expat contained dozens of security exposure bugs, the Xmlrpc-c maintainer decided to make external Libxml2 the default." I did offer a patch to use system libexpat [6] to the point where folder lib/expat/ could be fully deleted in packaging (to be accident proof), but there was no interest from upstream. That patch hence went into Gentoo packaging downstream [6] instead.

If you need help with porting that patch to different versions of xmlrpc-c, I may be able to help.

Best

Sebastian

[0] https://github.com/signalwire/freeswitch/pull/2768 [1] https://github.com/openwrt/packages/issues/26263 [2] https://bugs.gentoo.org/952113

A flaw was found in rsync. When using the --safe-links option, rsync fails to properly verify if a symbolic link destination contains another symbolic link within it. This results in a path traversal vulnerability, which may lead to arbitrary file write outside the desired directory.

A path traversal vulnerability exists in rsync. It stems from behavior enabled by the --inc-recursive option, a default-enabled option for many client options and can be enabled by the server even if not explicitly enabled by the client. When using the --inc-recursive option, a lack of proper symlink verification coupled with deduplication checks occurring on a per-file-list basis could allow a server to write files outside of the client's intended destination directory. A malicious server could write malicious files to arbitrary locations named after valid directories/paths on the client.

A flaw was found in rsync. It could allow a server to enumerate the contents of an arbitrary file from the client's machine. This issue occurs when files are being copied from a client to a server. During this process, the rsync server will send checksums of local data to the client to compare with in order to determine what data needs to be sent to the server. By sending specially constructed checksum values for arbitrary files, an attacker may be able to reconstruct the data of those files byte-by-byte based on the responses from the client.

A flaw was found in rsync which could be triggered when rsync compares file checksums. This flaw allows an attacker to manipulate the checksum length (s2length) to cause a comparison between a checksum and uninitialized memory and leak one byte of uninitialized stack data at a time.

A heap-based buffer overflow flaw was found in the rsync daemon. This issue is due to improper handling of attacker-controlled checksum lengths (s2length) in the code. When MAXDIGESTLEN exceeds the fixed SUMLENGTH (16 bytes), an attacker can write out of bounds in the sum2 buffer.

pkgpostinst in the Gentoo ebuild for Slurm through 22.05.3 unnecessarily calls chown to assign root's ownership on files in the live root filesystem. This could be exploited by the slurm user to become the owner of root-owned files.

In Gentoo Portage before 3.0.47, there is missing PGP validation of executed code: the standalone emerge-webrsync downloads a .gpgsig file but does not perform signature verification. Unless emerge-webrsync is used, Portage is not vulnerable.

Summary

Terrapin is a prefix truncation attack targeting the SSH protocol. More precisely, Terrapin breaks the integrity of SSH's secure channel. By carefully adjusting the sequence numbers during the handshake, an attacker can remove an arbitrary amount of messages sent by the client or server at the beginning of the secure channel without the client or server noticing it.

Mitigations

To mitigate this protocol vulnerability, OpenSSH suggested a so-called "strict kex" which alters the SSH handshake to ensure a Man-in-the-Middle attacker cannot introduce unauthenticated messages as well as convey sequence number manipulation across handshakes.

Warning: To take effect, both the client and server must support this countermeasure.

As a stop-gap measure, peers may also (temporarily) disable the affected algorithms and use unaffected alternatives like AES-GCM instead until patches are available.

Details

The SSH specifications of ChaCha20-Poly1305 (chacha20-poly1305@openssh.com) and Encrypt-then-MAC (-etm@openssh.com MACs) are vulnerable against an arbitrary prefix truncation attack (a.k.a. Terrapin attack). This allows for an extension negotiation downgrade by stripping the SSHMSGEXTINFO sent after the first message after SSHMSGNEWKEYS, downgrading security, and disabling attack countermeasures in some versions of OpenSSH. When targeting Encrypt-then-MAC, this attack requires the use of a CBC cipher to be practically exploitable due to the internal workings of the cipher mode. Additionally, this novel attack technique can be used to exploit previously unexploitable implementation flaws in a Man-in-the-Middle scenario.

The attack works by an attacker injecting an arbitrary number of SSHMSGIGNORE messages during the initial key exchange and consequently removing the same number of messages just after the initial key exchange has concluded. This is possible due to missing authentication of the excess SSHMSGIGNORE messages and the fact that the implicit sequence numbers used within the SSH protocol are only checked after the initial key exchange.

In the case of ChaCha20-Poly1305, the attack is guaranteed to work on every connection as this cipher does not maintain an internal state other than the message's sequence number. In the case of Encrypt-Then-MAC, practical exploitation requires the use of a CBC cipher; while theoretical integrity is broken for all ciphers when using this mode, message processing will fail at the application layer for CTR and stream ciphers.

For more details see https://terrapin-attack.com.

Impact

This attack targets the specification of ChaCha20-Poly1305 (chacha20-poly1305@openssh.com) and Encrypt-then-MAC (-etm@openssh.com), which are widely adopted by well-known SSH implementations and can be considered de-facto standard. These algorithms can be practically exploited; however, in the case of Encrypt-Then-MAC, we additionally require the use of a CBC cipher. As a consequence, this attack works against all well-behaving SSH implementations supporting either of those algorithms and can be used to downgrade (but not fully strip) connection security in case SSH extension negotiation (RFC8308) is supported. The attack may also enable attackers to exploit certain implementation flaws in a man-in-the-middle (MitM) scenario.

Soko if the code that powers packages.gentoo.org. Prior to version 1.0.2, the two package search handlers, Search and SearchFeed, implemented in pkg/app/handler/packages/search.go, are affected by a SQL injection via the q parameter. As a result, unauthenticated attackers can execute arbitrary SQL queries on https://packages.gentoo.org/. It was also demonstrated that primitive was enough to gain code execution in the context of the PostgreSQL container. The issue was addressed in commit 4fa6e4b619c0362728955b6ec56eab0e0cbf1e23y of version 1.0.2 using prepared statements to interpolate user-controlled data in SQL queries.

Gentoo soko is the code that powers packages.gentoo.org. Versions prior to 1.0.1 are vulnerable to SQL Injection, leading to a Denial of Service. If the user selects (in user preferences) the "Recently Visited Packages" view for the index page, the value of the searchhistory cookie is used as a base64 encoded comma separated list of atoms. These are string loaded directly into the SQL query with atom = '%s' format string. As a result, any user can modify the browser's cookie value and inject most SQL queries. A proof of concept malformed cookie was generated that wiped the database or changed it's content. On the database, only public data is stored, so there is no confidentiality issues to site users. If it is known that the database was modified, a full restoration of data is possible by performing a full database wipe and performing full update of all components. This issue is patched with commit id 5ae9ca83b73. Version 1.0.1 contains the patch. If users are unable to upgrade immediately, the following workarounds may be applied: (1.) Use a proxy to always drop the searchhistory cookie until upgraded. The impact on user experience is low. (2.) Sanitize to the value of searchhistory cookie after base64 decoding it.

USBView 2.1 before 2.2 allows some local users (e.g., ones logged in via SSH) to execute arbitrary code as root because certain Polkit settings (e.g., allowany=yes) for pkexec disable the authentication requirement. Code execution can, for example, use the --gtk-module option. This affects Ubuntu, Debian, and Gentoo.

Gentoo Portage through 2.3.84 allows local users to place a Trojan horse plugin in the /usr/lib64/nagios/plugins directory by leveraging access to the nagios user account, because this directory is writable in between a call to emake and a call to fowners.

The Gentoo app-backup/burp package before 2.1.32 has incorrect group ownership of the /etc/burp directory, which might allow local users to obtain read and write access to arbitrary files by leveraging access to a certain account for a burp-server.conf change.

The Gentoo app-backup/burp package before 2.1.32 sets the ownership of the PID file directory to the burp account, which might allow local users to kill arbitrary processes by leveraging access to this account for PID file modification before a root script sends a SIGKILL.

The Gentoo net-im/jabberd2 package through 2.6.1 sets the ownership of /var/run/jabber to the jabber account, which might allow local users to kill arbitrary processes by leveraging access to this account for PID file modification before a root script executes a "kill -TERM cat /var/run/jabber/filename.pid" command.

The Gentoo net-im/jabberd2 package through 2.6.1 installs jabberd, jabberd2-c2s, jabberd2-router, jabberd2-s2s, and jabberd2-sm in /usr/bin owned by the jabber account, which might allow local users to gain privileges by leveraging access to this account and then waiting for root to execute one of these programs.

The installation scripts in the Gentoo dev-db/mysql, dev-db/mariadb, dev-db/percona-server, dev-db/mysql-cluster, and dev-db/mariadb-galera packages before 2017-09-29 have chown calls for user-writable directory trees, which allows local users to gain privileges by leveraging access to the mysql account for creation of a link.

The init script in the Gentoo app-admin/logstash-bin package before 5.5.3 and 5.6.x before 5.6.1 has "chown -R" calls for user-writable directory trees, which allows local users to gain privileges by leveraging access to a $LSUSER account for creation of a hard link.

The Gentoo sci-mathematics/gimps package before 28.10-r1 for Great Internet Mersenne Prime Search (GIMPS) allows local users to gain privileges by creating a hard link under /var/lib/gimps, because an unsafe "chown -R" command is executed.

flower.initd in the Gentoo dev-python/flower package before 0.9.1-r1 for Celery Flower sets PID file ownership to a non-root account, which might allow local users to kill arbitrary processes by leveraging access to this non-root account for PID file modification before a root script executes a "kill cat /pathname" command.

Ebuild in Gentoo may change directory and file permissions depending on the order of installed packages, which allows local users to read or write to restricted directories or execute restricted commands via navigating to the affected directories, or executing the affected commands.

Eval injection vulnerability in xdg-utils 1.1.0 RC1, when no supported desktop environment is identified, allows context-dependent attackers to execute arbitrary code via the URL argument to xdg-open.

The urlopen function in pym/portage/util/urlopen.py in Gentoo Portage 2.1.12, when using HTTPS, does not verify X.509 certificates from SSL servers, which allows man-in-the-middle attackers to spoof servers and modify binary package lists via a crafted certificate.

Integer overflow in the trbitfieldEnsureNthBitAlloced function in bitfield.c in Transmission before 2.84 allows remote attackers to cause a denial of service and possibly execute arbitrary code via a crafted peer message, which triggers an out-of-bounds write.

The Gentoo Nullmailer package before 1.11-r2 uses world-readable permissions for /etc/nullmailer/remotes, which allows local users to obtain SMTP authentication credentials by reading the file.

MediaWiki before 1.19.6 and 1.20.x before 1.20.5 allows remote attackers to conduct cross-site scripting (XSS) attacks, as demonstrated by a CDATA section containing valid UTF-7 encoded sequences in a SVG file, which is then incorrectly interpreted as UTF-8 by Chrome and Firefox.

MediaWiki before 1.19.6 and 1.20.x before 1.20.5 does not allow extensions to prevent password changes without using both Special:PasswordReset and Special:ChangePassword, which allows remote attackers to bypass the intended restrictions of an extension that only implements one of these blocks.

Multiple heap-based buffer overflows in Aircrack-ng before 1.1 allow remote attackers to cause a denial of service (crash) and execute arbitrary code via a (1) large length value in an EAPOL packet or (2) long EAPOL packet.