{"id":"AZL-90077","summary":"CVE-2026-47734 affecting package python-dulwich 0.21.7-6","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":"2026-08-30T05:24:52Z","published":"2026-06-10T23:16:48Z","upstream":["CVE-2026-47734"],"references":[{"type":"WEB","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-47734"}],"affected":[{"package":{"name":"python-dulwich","ecosystem":"Azure Linux:3","purl":"pkg:rpm/azure-linux/python-dulwich"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"last_affected":"0.21.7-6"}]}],"database_specific":{"source":"https://github.com/microsoft/AzureLinuxVulnerabilityData/blob/main/osv/AZL-90077.json"}}],"schema_version":"1.9.0"}