high7.5
CVE-2026-33540
Distribution affected by pull-through cache credential exfiltration via www-authenticate bearer realm
Impact
Distribution is a toolkit to pack, ship, store, and deliver container content. Prior to 3.1.0, in pull-through cache mode, distribution discovers token auth endpoints by parsing WWW-Authenticate challenges returned by the configured upstream registry. The realm URL from a bearer challenge is used without validating that it matches the upstream registry host. As a result, an attacker-controlled upstream (or an attacker with MitM position to the upstream) can cause distribution to send the configured upstream credentials via basic auth to an attacker-controlled realm URL. This vulnerability is fixed in 3.1.0.
Affected packages
| Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|
| go | github.com/distribution/distribution/v3 | < 3.1.0 | 3.1.0 |
| go | github.com/distribution/distribution | <= 2.8.3 | none recorded |
Affected products
| Vendor | Product | Affected versions |
|---|---|---|
| Distribution Project | Distribution | before 3.1.0 |
Weakness classification
References
- NVD record
- CVE.org record
- GitHub advisory
- https://github.com/advisories/GHSA-3p65-76g6-3w7r
- https://github.com/distribution/distribution/security/advisories/GHSA-3p65-76g6-3w7r
- https://nvd.nist.gov/vuln/detail/CVE-2026-33540
- https://github.com/distribution/distribution/commit/cc5d5fa4ba02157501e6afa2cc6a903ad0338e7b