Summary
Gitea: Git LFS object reuse allows non-Code access to authorize private source objects
A user with Code write access to one repository may be able to associate an existing Git LFS object from a private source repository with their target repository, even when they do not have Code access to the source repository that currently owns the LFS object.
The issue appears to be caused by the source-object authorization check using broad repository accessibility instead of requiring Code-unit access to at least one repository that owns the requested LFS object.
Preconditions
The attacker needs:
- an authenticated Gitea account;
- Code write access to a target repository;
- non-Code access, such as Issues access, to a private source repository;
- knowledge of an existing Git LFS object OID and size from the private source repository.
Affected Area
The issue affects the Git LFS upload/object reuse path.
Relevant paths:
services/lfs/server.go
Relevant handlers:
BatchHandler
UploadHandler
Both paths can call:
git_model.LFSObjectAccessible(ctx, ctx.Doer, p.Oid)
The helper is located in:
models/git/lfs.go
The authorization check uses:
repo_model.AccessibleRepositoryCondition(user, unit.TypeInvalid)
When unit.TypeInvalid is used, the repository access condition can include broad repository access, such as organization team membership through team_repo and team_user, without requiring that the user has access to the Code unit of the source repository.
By contrast, Code-specific repository access checks use a concrete unit type and include team_unit validation.
Validation
I reproduced this locally using Gitea's Go test harness.
Validated against commit:
dac41a124fd34820a3c8caf3b3592ba62cd514ff
The PoC creates the following scenario:
- The attacker has Code write access to the target repository.
- The source repository is private.
- The attacker does not have Code access to the source repository.
- The attacker only has Issues access to the source repository through an organization team.
- An LFS object exists in the source repository.
LFSObjectAccessible(ctx, attacker, oid)returnstrue.NewLFSMetaObject(ctx, targetRepo.ID, pointer)successfully creates LFS metadata for the target repository.
Test result:
=== RUN TestLFSObjectAccessibleAllowsNonCodeSourceAccess
--- PASS: TestLFSObjectAccessibleAllowsNonCodeSourceAccess
PASS
ok gitea.dev/models/git
No live instance was tested. Validation was performed only against a local test database.
Security Expectation
A user should not be allowed to reuse or associate an LFS object from a private source repository unless they have Code access to that source repository, or another permission level explicitly intended to grant access to repository file contents.
Non-Code permissions such as Issues access should not authorize access to Git LFS object content or allow Git LFS object reuse.
Suggested Severity
Suggested severity: Medium to High.
The severity depends on whether the associated LFS object becomes downloadable through the target repository after reuse.
If the object becomes downloadable through the target repository, the issue should be considered High because it can lead to cross-repository Git LFS content disclosure.
Suggested CVSS v3.1 if content disclosure is confirmed:
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:L/A:N
Rationale:
- network reachable through Git LFS endpoints;
- requires authentication;
- requires knowledge of the LFS object OID and size;
- no user interaction required;
- breaks repository-level authorization expectations;
- primary impact is confidentiality of private Git LFS content;
- limited integrity impact through unauthorized LFS metadata association in the target repository.
Evidence
I can provide the local regression test and passing test log privately if needed.
Impact
This issue breaks the expected authorization boundary between repository units.
A user who does not have Code access to a private source repository should not be able to reuse or associate Git LFS objects owned by that repository. However, because the source-object accessibility check accepts broad repository access, non-Code access such as Issues access may be sufficient for the LFS object to be treated as accessible.
If the reused object becomes downloadable through the attacker-controlled target repository after metadata association, this can result in cross-repository Git LFS content disclosure.
The target repository write authorization is still enforced. The problem is specifically in the authorization decision for whether the source LFS object is accessible and may be reused.
The application does not correctly enforce access controls, allowing a principal to access resources or operations beyond their granted permissions. Typical impact: unauthorized data access or execution of privileged operations.
CVE-2026-28740 has a CVSS score of 7.1 (High). The vector is network-reachable, low privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (1.26.3); upgrading removes the vulnerable code path.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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See it in your environmentNew to Kodem? Get a demo →Remediation advice
LFSObjectAccessible should require Code-unit access to at least one repository that owns the requested LFS object.
The check should avoid using unit.TypeInvalid for this source-object authorization decision. A Code-specific repository access condition should be used instead.
A regression test should cover:
- private source repository;
- user has Issues-only access to the source repository;
- user does not have Code access to the source repository;
- user has Code write access to the target repository;
- known LFS object exists in the source repository;
- object reuse must be rejected unless the user has Code access to the source repository.
Frequently Asked Questions
- What is CVE-2026-28740? CVE-2026-28740 is a high-severity incorrect authorization vulnerability in gitea.dev (go), affecting versions < 1.26.3. It is fixed in 1.26.3. The application does not correctly enforce access controls, allowing a principal to access resources or operations beyond their granted permissions.
- How severe is CVE-2026-28740? CVE-2026-28740 has a CVSS score of 7.1 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
- Which versions of gitea.dev are affected by CVE-2026-28740? gitea.dev (go) versions < 1.26.3 is affected.
- Is there a fix for CVE-2026-28740? Yes. CVE-2026-28740 is fixed in 1.26.3. Upgrade to this version or later.
- Is CVE-2026-28740 exploitable, and should I be worried? Whether CVE-2026-28740 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2026-28740 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2026-28740? Upgrade
gitea.devto 1.26.3 or later.