VulnerabilityPublished 13 Aug 2026Updated 4 Nov 2026

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

Affects conda-lockSource 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 4.0.5 when convenient.

Data as of 4 Nov 2026, 20:36 UTC

CVSS 3.1 base score

5.7Medium

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.1% chance of exploitation in 30 days – higher than 8% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 4.0.5

CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:N/A:H

Attack Vector: Network
Attack Complexity: Low
Privileges Required: Low
User Interaction: Required
Scope: Unchanged
Confidentiality: None
Integrity: None
Availability: High

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: Low: The attacker is authorized with (i.e., requires) privileges that provide basic user capabilities that could normally affect only settings and files owned by a user. Alternatively, an attacker with Low privileges may have the ability to cause an impact only to non-sensitive resources.
User Interaction: Required: Successful exploitation of this vulnerability requires a user to take some action before the vulnerability can be exploited.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: None: There is no loss of confidentiality within the impacted component.
Integrity: None: There is no loss of integrity within the impacted component.
Availability: High: There is total loss of availability, resulting in the attacker being able to fully deny access to resources in the impacted component; this loss is either sustained (while the attacker continues to deliver the attack) or persistent (the condition persists even after the attack has completed). Alternatively, the attacker has the ability to deny some availability, but the loss of availability presents a direct, serious consequence to the impacted component (e.g., the attacker cannot disrupt existing connections, but can prevent new connections; the attacker can repeatedly exploit a vulnerability that, in each instance of a successful attack, leaks a only small amount of memory, but after repeated exploitation causes a service to become completely unavailable).

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 10 Jun 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by 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 4 Nov 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade conda-lock to 4.0.5.

Affected software

Product	Affected	Fixed in
Homebrewconda-lock`pkg:brew/conda-lock`Other threats	Affected >=3.0.0 <4.0.5	Fixed in 4.0.5

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

AI-suggested

Upgrade Dulwich to version 1.2.5 or later, which includes a fix that enforces a maximum input size to prevent excessive memory allocation. Configure receive.maxInputSize in the repository configuration to a reasonable limit for your environment. Until patched, restrict push access to trusted, authenticated clients only or disable push functionality if not needed. Additionally, run the server with OS-level memory limits (e.g., ulimit, cgroups, container memory limits) to contain potential memory exhaustion attacks.

Description

CVE-2026-47734 is a denial-of-service vulnerability in Dulwich, a Python Git library, caused by unbounded memory allocation when processing crafted thin packs during git push operations. An attacker with push access can send a tiny crafted thin pack that declares a large destination size, causing Dulwich to allocate excessive memory and potentially exhaust system resources. This affects Dulwich-based Git servers exposing git-receive-pack functionality. The issue is patched in Dulwich version 1.2.5 and later.

Impact

An attacker with push access can cause a denial-of-service by exhausting server memory through a crafted thin pack with a large declared destination size. This impacts availability of Dulwich-based Git servers that accept pushes. There is no impact on confidentiality or integrity reported. The CVSS 3.1 score is 5.7 (medium severity) with vector AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:N/A:H.

Summary

The vulnerability involves Dulwich's add_thin_pack and apply_delta functions, which allocate memory based on an attacker-controlled dest_size field in a crafted thin pack during git push operations. This leads to uncontrolled resource consumption (memory exhaustion), resulting in a denial-of-service condition. Dulwich-based Git servers that accept pushes via dulwich.server, HTTP smart server, or ReceivePackHandler are impacted. The patch in version 1.2.5 introduces a max_input_size parameter to limit input size and prevent excessive memory allocation. The ReceivePackHandler reads receive.maxInputSize from repository config to enforce this limit and raises a PackInputTooLarge exception if exceeded. Prior to patching, receive.maxInputSize has no effect.

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Affected software

Description

AI analysisMachine-generated, updated 4 Nov 2026, 18:02 UTC

Technical details

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