{"id":"DEBIAN-CVE-2026-47734","details":"Dulwich is a pure-Python implementation of the Git file formats and protocols. Starting in version 0.1.0 and prior to version 1.2.5, a client with push access could push a tiny crafted thin pack (~174 bytes)  whose delta header declares a huge   dest_size. When dulwich ingested it via  add_thin_pack / apply_delta, it would  allocate hundreds of MB of memory based on that attacker-controlled size, with no relationship to the actual bytes received. Operators running a Dulwich-based Git server that exposes git-receive-pack (i.e. accepts pushes) - for example via dulwich.server functionality, the HTTP  smart server, or anything built on ReceivePackHandler - are impacted. The issue is patched in 1.2.5. add_thin_pack now accepts a max_input_size keyword (bytes; 0/None = unlimited, matching git's semantics), and ReceivePackHandler reads receive.maxInputSize from the repository config and passes it through. Wire reads are counted and a PackInputTooLarge exception is raised once the cap is exceeded - equivalent to git index-pack --max-input-size. Users should upgrade to Dulwich 1.2.5 or later and set receive.maxInputSize in their server's repository config to a sane bound for their environment. On unpatched versions, receive.maxInputSize has no effect, so it cannot be used as a workaround. Until upgrading, operators should restrict dulwich-receive-pack (push) access to trusted, authenticated clients only, or disable it entirely on servers that only need to serve fetches and/or run the server under an OS-level memory limit (e.g. ulimit, cgroups/MemoryMax, or a container memory limit) so a malicious push is killed rather than taking down the host.","modified":"2026-09-14T17:03:16.230079546Z","published":"2026-06-10T23:16:48.807Z","upstream":["CVE-2026-47734"],"references":[{"type":"ADVISORY","url":"https://security-tracker.debian.org/tracker/CVE-2026-47734"}],"affected":[{"package":{"name":"dulwich","ecosystem":"Debian:12","purl":"pkg:deb/debian/dulwich?arch=source&distro=bookworm"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["0.21.2-1","0.21.5-1","0.21.6-1","0.22.5-1","0.22.7-1","0.22.7-2","0.24.10-1","0.24.2-1","0.24.2-2","1.0.0-1","1.0.0-2","1.1.0-1","1.1.0-2","1.1.0-3","1.2.0-1","1.2.1-1","1.2.11-1","1.2.12-1","1.2.5-1","1.2.7-1","1.2.7-2"],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-47734.json"}},{"package":{"name":"dulwich","ecosystem":"Debian:13","purl":"pkg:deb/debian/dulwich?arch=source&distro=trixie"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["0.22.7-1","0.22.7-2","0.24.10-1","0.24.2-1","0.24.2-2","1.0.0-1","1.0.0-2","1.1.0-1","1.1.0-2","1.1.0-3","1.2.0-1","1.2.1-1","1.2.11-1","1.2.12-1","1.2.5-1","1.2.7-1","1.2.7-2"],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-47734.json"}},{"package":{"name":"dulwich","ecosystem":"Debian:14","purl":"pkg:deb/debian/dulwich?arch=source&distro=forky"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.2.5-1"}]}],"versions":["0.22.7-1","0.22.7-2","0.24.10-1","0.24.2-1","0.24.2-2","1.0.0-1","1.0.0-2","1.1.0-1","1.1.0-2","1.1.0-3","1.2.0-1","1.2.1-1"],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-47734.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:N/A:H"}]}