A flaw was found in tar. A remote attacker could exploit this vulnerability by crafting a malicious archive, leading to hidden file injection with fully attacker-controlled content. This bypasses pre-extraction inspection mechanisms, potentially allowing an attacker to introduce malicious files onto a system without detection.

A flaw was found in polkit. A local user can exploit this by providing a specially crafted, excessively long input to the polkit-agent-helper-1 setuid binary via standard input (stdin). This unbounded input can lead to an out-of-memory (OOM) condition, resulting in a Denial of Service (DoS) for the system.

A flaw was found in GNU tar. The --one-top-level option is intended to confine extraction under a designated directory, but hardlink targets from the archive are not confined the same way and are resolved relative to the extraction working directory (or the directory given with -C). A crafted archive can create hardlinks inside the --one-top-level directory that point to files outside it. If a suitable symbolic link already exists under the extraction working directory, hardlinking to that symlink can bypass tar's usual symlink-based path protections and allow writing outside the intended top-level directory during a single extraction. Users who rely on --one-top-level as a security boundary when extracting untrusted archives may be affected.

A TOCTOU (Time-of-Check Time-of-Use) vulnerability in GNU tar's incremental dumpdir 'X' rename handling allows a local attacker with write access to a directory being backed up to influence the restore process if the attacker has access to the system where the restore is being performed. During restoration, files or directories may be created, renamed or overwritten outside the intended extraction directory. This could lead to unauthorized file modification or, in some cases, privilege escalation. Exploitation does not require the attacker to modify or craft the archive, and standard backup and restore workflows—including extracting into a newly created directory without using the -P option do not mitigate the issue.

A flaw was found in libssh channel handling. In sshpacketchannelopen() in src/messages.c and sshpacketchannelopenconf() in src/channels.c, the implementation accepts a peer-controlled maximum packet size of 0 in channel open messages. That zero value is stored in channel state and later reaches channelwritecommon(), where forward progress depends on the remote maximum packet size being positive; with 0, the remaining length is never reduced and the write path loops indefinitely, consuming CPU and causing denial of service. A remote authenticated peer can trigger this by advertising a zero maximum packet size in SSHMSGCHANNELOPEN or SSHMSGCHANNELOPENCONFIRMATION.

A flaw was found in libssh client-side ProxyCommand handling. In sshsocketconnectproxycommand() in src/socket.c, the return value of fork() was not checked before being stored as the proxy child PID. If fork() fails, the value -1 can be retained in state and later used during cleanup, causing signals to be sent across the caller's accessible process tree. In deployments that use ProxyCommand, this can lead to local denial of service.

A flaw was found in libssh server-side SFTP request handling. In sftpmakeclientmessage() and the downstream processread() path in src/sftpserver.c, the implementation accepts a client-controlled SSHFXPREAD length without enforcing a reasonable upper bound. The parsed len field later drives memory allocation in the SFTP server read path, so a remote authenticated client can request an excessively large read length and force the server to allocate excessive memory. Repeated requests can exhaust available memory and lead to denial of service.

A flaw was found in libssh client-side SFTP message handling. In sftpgetmessage() in src/sftpcommon.c, SFTP responses carrying unknown request IDs were accepted and kept queued instead of being rejected. A malicious SFTP server can repeatedly send responses for request IDs that were never issued by the client, causing unbounded growth of queued messages and leading to client-side memory exhaustion and denial of service.

A flaw was found in the GStreamer gst-plugins-bad package. When processing a malformed H.266/VVC video stream with a crafted aspect ratio indicator value, the H.266 parser performs an out-of-bounds read of up to 8 bytes from adjacent memory. This flaw allows an attacker to craft a malicious H.266 video file or stream that, when processed by a GStreamer-based application, could leak limited memory contents through video metadata, potentially exposing sensitive information from the application's address space.

A 1-byte heap out-of-bounds read vulnerability exists in the gsth264parseprocessnal() function in subprojects/gst-plugins-bad/gst/videoparsers/gsth264parse.c. The function processes H.264 NAL units including GSTH264NALSLICEEXT (NAL type 20) for MVC/SVC extension slices. At line 1132, the code dereferences (nalu->data + nalu->offset + nalu->headerbytes) to check the firstmbinslice flag without first verifying that nalu->size > nalu->headerbytes. For extension slice types, headerbytes is set to 4 (1 byte base + 3 bytes extension header per gsth264parser.c:243). A malformed NAL unit with exactly size==4 passes the minimum size check (size >= 2 at line 999) but triggers a 1-byte read at offset 4, which is beyond the allocated buffer. The same bounds check pattern is correctly implemented in gsth264parsecollectnal() at line 1259 with if (nalu->size > nalu->headerbytes). The vulnerability affects GStreamer 1.x versions (tested against git version 1.29.1.1). Upstream maintainer Sebastian Droege confirmed the vulnerability via GitLab work item 5108. Reported by Dr. Faruk Kazi, Ramesh Adhikari, and Ariba Afroz from CoE-CNDS Lab, VJTI, Mumbai, India. PSIRT Ticket: PSIRTSUPT-17585.

Last updated 30 June 2026

A flaw was found in OpenSSH. A local unprivileged attacker on a Linux client host can hijack client-side X11 forwarding connections. This is possible by pre-binding the preferred abstract X socket name when X11 forwarding is enabled and a local UNIX-domain X socket is used. A successful attack can compromise the confidentiality of forwarded X11 traffic, including sensitive window contents and input, and may allow some manipulation of the forwarded session.

A flaw was found in OpenSSH. A malicious SSH server can exploit a double free vulnerability in the Diffie-Hellman Group Exchange (DH-GEX) client path. This occurs during FIPS (Federal Information Processing Standards) mode known-group validation when the client processes attacker-controlled DH-GEX group parameters. Successful exploitation leads to client-side process termination, resulting in a Denial of Service (DoS).

A flaw was found in Samba’s vfsworm module. The module is intended to provide write-once, read-many (WORM) protections by preventing modification of files after a configurable grace period. Due to insufficient validation during rename operations, an authenticated user with write access to a share could overwrite a protected file by renaming a newly created file over the existing WORM-protected file.

A flaw was found in sblim-cmpi-base. Insecure temporary file creation in the provider registration scripts allows a local unprivileged user to perform a symlink attack. By creating a symlink in a world-writable directory, an attacker can redirect privileged writes to an arbitrary file during script execution in a privileged context. This can lead to the overwrite of root-owned files, potentially disrupting system services or operation. Exploitation is conditional on the script running with elevated privileges and may be mitigated by sticky-directory symlink protections.

A flaw was found in GStreamer gst-plugins-good (avidemux). In gstavidemuxriffparsevprp(), the number of available gstriffvprpvideofielddesc entries is calculated by dividing the remaining buffer size by the attacker-controlled vprp->fields value, rather than by sizeof(gstriffvprpvideofielddesc). This can cause the parser to treat more field descriptors as available than fit in the input buffer, resulting in out-of-bounds reads. Processing a crafted AVI via playbin/decodebin can crash the application (denial of service). Fixed upstream in gst-plugins-good 1.28.6 (GStreamer-SA-2026-0072).

A flaw was found in GStreamer gst-plugins-good (avidemux). When parsing FUJIFILM metadata in an AVI strd chunk, gstavidemuxparsestrd() decrements a remaining-length counter by fixed offsets (98 and 10 bytes) without verifying sufficient data remains. For crafted strd payloads of exactly 106 or 107 bytes, the counter underflows to a very large unsigned value, causing subsequent null-terminated string scanning to read far beyond the allocated heap buffer. Date-format normalization may also write beyond the buffer end. Confirmed impacts include heap out-of-bounds read, out-of-bounds write, heap information disclosure (adjacent data appearing in parsed metadata), and application crash/denial of service. The avidemux element is auto-plugged by playbin, decodebin, and gst-discoverer, so opening or previewing a crafted AVI is sufficient to trigger the issue. Fixed upstream in gst-plugins-good 1.28.6 (GStreamer-SA-2026-0072).

A flaw was found in sblim-sfcb. A local, low-privileged attacker can exploit a race condition during privileged instance migration by manipulating a temporary file in the /tmp directory. By repeatedly recreating a symbolic link, the attacker can redirect privileged output to an arbitrary file. This can lead to privileged file corruption or a denial of service (DoS) on the system.

A flaw was found in sblim-sfcb. A local attacker with access to the system can exploit an unsafe deserialization vulnerability in the provider-manager's inter-process communication (IPC) message parsing. By sending a specially crafted message, the attacker can cause out-of-bounds memory access, leading to the termination of the provider-manager process and a denial of service. This could also potentially result in limited unintended information disclosure.

A flaw was found in binutils, specifically within the readelf utility. This vulnerability allows a local attacker to cause a Denial of Service (DoS) by tricking a user into processing a specially crafted Executable and Linkable Format (ELF) file. The exploitation of this flaw can lead to the system becoming unresponsive due to excessive resource consumption or a program crash.

A flaw was found in firewalld. A local unprivileged user can exploit this vulnerability by mis-authorizing two runtime D-Bus (Desktop Bus) setters, setZoneSettings2 and setPolicySettings. This mis-authorization allows the user to modify the runtime firewall state without proper authentication, leading to unauthorized changes in network security configurations.

A flaw was found in the GNU Binutils BFD library, a widely used component for handling binary files such as object files and executables. The issue occurs when processing specially crafted XCOFF object files, where a relocation type value is not properly validated before being used. This can cause the program to read memory outside of intended bounds. As a result, affected tools may crash or expose unintended memory contents, leading to denial-of-service or limited information disclosure risks.

A flaw was found in libsoup. A remote attacker, by controlling the method parameter of the soupmessagenew() function, could inject arbitrary headers and additional request data. This vulnerability, known as CRLF (Carriage Return Line Feed) injection, occurs because the method value is not properly escaped during request line construction, potentially leading to HTTP request injection.

A flaw was found in libsoup, a library used by applications to send network requests. This vulnerability occurs because libsoup does not properly validate hostnames, allowing special characters to be injected into HTTP headers. A remote attacker could exploit this to perform HTTP smuggling, where they can send hidden, malicious requests alongside legitimate ones. In certain situations, this could lead to Server-Side Request Forgery (SSRF), enabling an attacker to force the server to make unauthorized requests to other internal or external systems. The impact is low, as SoupServer is not actually used in internet infrastructure.

A flaw was found in gnuplot. The xstrftime() function may lead to a segmentation fault, causing a system crash.

A flaw was found in gnuplot. The plot3dpoints() function may lead to a segmentation fault and cause a system crash.

A flaw was found in open-iscsi. This vulnerability allows a remote attacker on the same local network segment to cause a Denial of Service (DoS) in the iscsiuio daemon. By sending a specially crafted Internet Control Message Protocol version 6 (ICMPv6) Router Advertisement with a zero-length option, the attacker can trigger an infinite loop. This leads to sustained CPU usage, rendering the daemon unresponsive and impacting system availability. A secondary risk of out-of-bounds reads exists with a short IPv6 payload, though no memory corruption or data exposure has been confirmed.

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.

A flow has been identified into dnssec.c library, causing an infinite loop to dnsmasq service. An attacker who controls any DNSSEC-signed zone can hang the dnsmasq process with a single crafted response, killing all DNS resolution for its clients.

A flaw was found in GIMP's file-png plugin. A remote attacker can exploit this by crafting a malicious Animated Portable Network Graphics (APNG) image containing an oversized tRNS chunk. This can lead to a stack-based buffer overflow (CWE-121), causing the file-png plugin to crash and resulting in a Denial of Service (DoS) for the user.