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VulnerabilityPublished Updated

CVE-2026-47734: Dvc · Dulwich has unbounded memory allocation in receive-pack from crafted thin packs

Affects dvcSource GCVE Database

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Authoritative record:CVE-2026-47734· Medium 5.7

Not known to be exploited · CVSS 5.7 Medium : upgrade to 3.67.1_6 when convenient.

Data as of 30 Oct 2026, 05:29 UTC

CVSS 3.1 base score
5.7Medium
How severe the flaw is on the 0–10 CVSS scale.
Patch
Available – fixed in 3.67.1_6
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:N/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 10 Jun 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 29 Oct 2026.

What to do

Upgrade dvc to 3.67.1_6.

Affected software

ProductAffectedFixed in
Homebrewdvcpkg:brew/dvcOther threatsAffected
  • >=1.10.1 <3.67.1_6
Fixed in
  • 3.67.1_6

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

Description

## Impact An uncontrolled-resource-consumption (memory exhaustion) denial-of-service vulnerability (CWE-400 / CWE-789). 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. Who is impacted: 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. ## Patches 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. ## Workarounds 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. - 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. ## Resources - git's receive.maxInputSize / git index-pack --max-input-size documentation - Reported by Liyi, Ziyue, Strick, Maurice and Chenchen @ University of Sydney

References

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