{"cve":"CVE-2026-47734","nvd":{"published":"2026-06-10T23:16:48.807","modified":"2026-07-23T09:10:00.113","status":"Deferred","description":"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.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:N/A:H","score":5.7},"cwes":["CWE-400","CWE-789"],"references":["https://github.com/jelmer/dulwich/releases/tag/dulwich-1.2.5","https://github.com/jelmer/dulwich/security/advisories/GHSA-xrvj-v92f-53gj"],"products":[],"source":"nvd","synced_at":"2026-10-19T22:38:48.522727527+00:00"},"epss":{"cve":"CVE-2026-47734","score":0.00188,"percentile":0.08464,"date":"2026-10-31"},"kev":null,"osv":[{"id":"GHSA-xrvj-v92f-53gj","url":"https://osv.dev/vulnerability/GHSA-xrvj-v92f-53gj","summary":"Dulwich has unbounded memory allocation in receive-pack from crafted thin packs","modified":"2026-07-13T16:43:32.716665118Z","packages":[{"ecosystem":"PyPI","name":"dulwich","purl":"pkg:pypi/dulwich","ranges":[">=0.1.0 <1.2.5"],"fixed":["1.2.5"]}]},{"id":"PYSEC-2026-2466","url":"https://osv.dev/vulnerability/PYSEC-2026-2466","summary":"Dulwich has unbounded memory allocation in receive-pack from crafted thin packs","modified":"2026-07-13T16:31:41.594863437Z","packages":[{"ecosystem":"PyPI","name":"dulwich","purl":"pkg:pypi/dulwich","ranges":[">=0.1.0 <1.2.5"],"fixed":["1.2.5"]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}