vulnerability / NVI-00005623 / Revision 5
Koel: Full-read SSRF via podcast enclosure URL: isPublicHost() filter_var guard does not reject NAT64 (64:ff9b::/96) or 6to4 (2002::/16) IPv6-transition wrappers of internal IPv4
GitHub lists this reviewed advisory for phanan/koel. Published version ranges and source prerequisites are shown below; this is not an inspection of a visitor’s application.
This report has not inspected your inventory, configuration, deployed build, reachability or evidence. A catalog listing and a severity score do not establish exposure or compromise.
01 / Meaning
Why it matters
Published affected context helps an owner decide what evidence to gather. This report has not examined your application.
5.3 MEDIUM (4.0)
security-advisories@github.com severity; no combined Null risk score.
0.427%
FIRST EPSS model v2026.06.15; exploitation probability over 30 days, percentile 0.37025. Missing scores are unknown.
As of · FIRST EPSS
02 / Applicability
The affected context
Affected versions, configuration prerequisites and known exclusions are public. Confirm each one against the deployed service.
phanan/koel
source listed<= 9.7.0
## Summary Koel's outbound-URL guard `App\Helpers\Network::isPublicHost()` classifies an IP as "public" using PHP's `filter_var($ip, FILTER_VALIDATE_IP, FILTER_FLAG_NO_PRIV_RANGE | FILTER_FLAG_NO_RES_RANGE)`. That flag set does **not** recognise IPv6 transition-address forms that embed a private/loopback/link-local IPv4: NAT64 well-known prefix `64:ff9b::/96` (RFC 6052) and 6to4 `2002::/16` (RFC 3056). An address such as `64:ff9b::7f00:1` (= `127.0.0.1`), `64:ff9b::a9fe:a9fe` (= `169.254.169.254`, the cloud metadata endpoint), or `2002:a00:1::` (= `10.0.0.1`) is reported as a public address, so the guard returns `true` and Koel proceeds to fetch the URL. The guard is the only SSRF defense in front of `App\Values\Podcast\EpisodePlayable::createForEpisode()`, which downloads a podcast episode with `Http::sink($file)->get($url)` and streams the response body back to the requesting user. Because an attacker fully controls the `` of any RSS feed they host (and any authenticated user can subscribe to a feed), they can publish an enclosure whose hostname has an `AAAA` record that is a NAT64/6to4 wrapper of an internal IP. On hosts with NAT64 or 6to4/dual-stack routing (th
phanan/koel
source listedECOSYSTEM: introduced 0; fixed 9.7.1
## Summary Koel's outbound-URL guard `App\Helpers\Network::isPublicHost()` classifies an IP as "public" using PHP's `filter_var($ip, FILTER_VALIDATE_IP, FILTER_FLAG_NO_PRIV_RANGE | FILTER_FLAG_NO_RES_RANGE)`. That flag set does **not** recognise IPv6 transition-address forms that embed a private/loopback/link-local IPv4: NAT64 well-known prefix `64:ff9b::/96` (RFC 6052) and 6to4 `2002::/16` (RFC 3056). An address such as `64:ff9b::7f00:1` (= `127.0.0.1`), `64:ff9b::a9fe:a9fe` (= `169.254.169.254`, the cloud metadata endpoint), or `2002:a00:1::` (= `10.0.0.1`) is reported as a public address, so the guard returns `true` and Koel proceeds to fetch the URL. The guard is the only SSRF defense in front of `App\Values\Podcast\EpisodePlayable::createForEpisode()`, which downloads a podcast episode with `Http::sink($file)->get($url)` and streams the response body back to the requesting user. Because an attacker fully controls the `` of any RSS feed they host (and any authenticated user can subscribe to a feed), they can publish an enclosure whose hostname has an `AAAA` record that is a NAT64/6to4 wrapper of an internal IP. On hosts with NAT64 or 6to4/dual-stack routing (th
03 / Response
What to do next
- investigate
Identify the exact component and deployed version, examine the linked publisher’s conditions, and retain evidence of any mitigation.
Confirm current vendor support, compatibility and deployment evidence. This report has not tested a fix in your system. FIRST EPSS
- vendor patch
The original advisory lists fixed boundaries 9.7.1 for phanan/koel. Confirm the publisher’s latest guidance.
Confirm current vendor support, compatibility and deployment evidence. This report has not tested a fix in your system. GitHub Advisory Database via OSV
A fixed release is not deployment evidence.
Check current vendor support and compatibility. After making a change, verify the deployed build and relevant runtime conditions. Keep the evidence, owner and time. An updated lockfile alone does not prove what is running.
04 / Limits
What this report cannot establish
- Customer inventory, deployment, reachability and exploitation have not been inspected.
- NVD lastModified does not establish freshness of every associated CPE record.
05 / Provenance
Sources you can inspect
Each assertion retains its source. Mirrored records may repeat one underlying publisher; additional links are not independent corroboration.
- GHSA-rjg7-r26h-cfp2 ↗
GitHub Advisory Database · vendor advisory
Observed . GitHub Advisory Database; CC-BY-4.0. Each advisory links its original attribution. Null normalizes fields.
- GHSA-rjg7-r26h-cfp2 ↗
GitHub Advisory Database via OSV · vendor advisory
Observed . GitHub-origin advisory, CC-BY-4.0; OSV is an aggregate copy, not independent corroboration.
- CVE-2026-54494 ↗
NIST National Vulnerability Database · official catalog
Observed . This product uses data from the NVD API but is not endorsed or certified by the NVD.
- CVE-2026-54494 ↗
FIRST EPSS · official catalog
Observed . FIRST EPSS; probability of exploitation in the next 30 days, not local compromise. Dataset date/model retained; FIRST services terms apply.
Public revision history
Only published revisions appear here. Routine fetches do not create a material-change event.
- Revision 5 ·
Source facts changed; compare the preserved prior revision.
- Revision 4 ·
Source facts changed; compare the preserved prior revision.
- Revision 2 ·
Dated EPSS estimate updated; this is not a new disclosure or proof of exploitation.
- Revision 1 ·
First indexed by Null; source disclosure date is shown separately.