BuildKit improperly handles special files in build snapshots

Package updates are available for Amazon Linux 2023 that fix the following vulnerabilities: CVE-2026-94440: Parsing a multipart form could bypass memory limits and read an arbitrarily long line into memory when the remaining limit at the start of a part was less than 400 bytes. Multipart form memory limits are now properly enforced in this situation. NOTE: https://www.openwall.com/lists/oss-security/2026/10/08/9 NOTE: https://github.com/golang/go/issues/81741 NOTE: Fixed by: https://github.com/golang/go/commit/7c79b50a74b6d1aa4269b1827dda7d81f3717f9d (go1.27.2) NOTE: Fixed by: https://github.com/golang/go/commit/d7a7aa8e6781ddf8dce12adf60a813d957d4763e (go1.26.9) CVE-2026-93320: BuildKit may be tricked into performing file actions with special file inodes where regular files are expected. Special files may block operations or, on rootful workers, allow unintended host device access. CVE-2026-92543: Docker Engine classifies a registry hostname as insecure using an any-match DNS check. loadInsecureRegistries() injects 127.0.0.0/8 and ::1/128 as insecure CIDRs by default. isCIDRMatch resolves all of the hostname's addresses and returns true if a single address is in the insecure CIDR list. Because the transport re-dials the hostname rather than the CIDR-matching address, a DNS answer set of one loopback IP plus a non-loopback attacker IP disables certificate verification and enables HTTP fallback for the registry connection. CVE-2026-92542: The firewall rules which mark VXLAN datagrams for encryption indiscriminately match both authentic VXLAN datagrams sent from the kernel and forged datagrams sent by user processes. Any packet sent from the host network namespace of a Linux Swarm node is encrypted with the overlay-network IPsec parameters which meets the following criteria: - UDP datagram - Destination port is the Swarm data-path port - Datagram starts with a VXLAN header for the VNI of an encrypted overlay network which any running container on the node is connected to CVE-2026-78667: When parsing a Range header containing a large number of small ranges, FileServer(FS), ServeContent, and ServeFile(FS) could consume an excessive amount of CPU. These functions now ignore Range headers containing more than 200 ranges. The limit is controlled by the new httpservecontentmaxranges=GODEBUG setting. Setting GODEBUG=httpservecontentmaxranges=0 disables the limit. NOTE: https://www.openwall.com/lists/oss-security/2026/10/08/9 NOTE: https://github.com/golang/go/issues/81858 NOTE: Fixed by: https://github.com/golang/go/commit/ababc3cd873d8acce1777268aa7a817e6b672028 (go1.27.2) NOTE: Fixed by: https://github.com/golang/go/commit/eb25b4e532c5a01f99ef860ec66743a8783f992b (go1.26.9) CVE-2026-78659: When "Trailer" headers are sent by a client, the HTTP server internally uses the header values to populate the Request.Trailer map passed to the server handler. Because Request.Trailer is a map, each entry incurs memory overhead. For HTTP/2 servers, a malicious client can exploit this by sending a "Trailer" header that declares a large number of fields causing the server to allocate a disproportionate amount of memory while bypassing Server.MaxHeaderValueCount and Server.MaxHeaderBytes limits. This exploit is not applicable for HTTP/1 servers, which do not support multiplexing a large number of requests over one TCP connection, and whose Server.MaxHeaderBytes are calculated differently. Server.MaxHeaderValueCount and Server.MaxHeaderBytes limits are now applied towards the trailer fields declared in "Trailer" headers. NOTE: https://www.openwall.com/lists/oss-security/2026/10/08/9 NOTE: https://github.com/golang/go/issues/81857 NOTE: Fixed by: https://github.com/golang/go/commit/cbb0fb8b51cba866018b8a0fb4b5458f16c5c80b (go1.27.2) NOTE: Fixed by: https://github.com/golang/go/commit/6e049521882c944afc1e519a83971ec421dc2974 (go1.26.9) CVE-2026-17106: The tar extraction routines in moby/go-archive (Unpack, UnpackLayer, Untar/UntarUncompressed, and the ApplyLayer helpers) do not confine filesystem operations to the destination directory. A crafted archive can create or overwrite files outside the intended destination.

Where it's fixed