CVE-2026-100355
Campfire vulnerable to SSRF via incomplete private-network denylist in the link-unfurl guard
Campfire is a web-based chat application. In version 1.4.4 and earlier, when a Campfire message contains a link, the server fetches it to build an OpenGraph unfurl preview. RestrictedHTTP::PrivateNetworkGuard relied on Ruby's IPAddr#private? `` IPAddr#loopback?, and IPAddr#link_local? predicates plus IPv4-mapped and IPv4-compatible checks, which do not cover several special-use ranges. An authenticated user can post a link to a hostname resolving to CGNAT 100.64.0.0/10, NAT64 64:ff9b::/96 or 64:ff9b:1::/48, or 6to4 2002::/16 to bypass the guard and cause server-side requests to internal network resources. The NAT64 and 6to4 ranges can embed an internal IPv4 target. Confidentiality impact is limited to returned OpenGraph metadata, and most internal endpoints return none. There is no integrity or availability impact. An initial fix was released in version 1.4.5.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- High
- Privileges needed
- Low
- User interaction
- None
What an attacker can affect
- Confidentiality
- Low
- Integrity
- None
- Availability
- None
Exploit likelihood
What each source reports
CVE List Score used
Campfire vulnerable to SSRF via incomplete private-network denylist in the link-unfurl guard
Campfire is a web-based chat application. In version 1.4.4 and earlier, when a Campfire message contains a link, the server fetches it to build an OpenGraph unfurl preview. RestrictedHTTP::PrivateNetworkGuard relied on Ruby's IPAddr#private? `` IPAddr#loopback?, and IPAddr#link_local? predicates plus IPv4-mapped and IPv4-compatible checks, which do not cover several special-use ranges. An authenticated user can post a link to a hostname resolving to CGNAT 100.64.0.0/10, NAT64 64:ff9b::/96 or 64:ff9b:1::/48, or 6to4 2002::/16 to bypass the guard and cause server-side requests to internal network resources. The NAT64 and 6to4 ranges can embed an internal IPv4 target. Confidentiality impact is limited to returned OpenGraph metadata, and most internal endpoints return none. There is no integrity or availability impact. An initial fix was released in version 1.4.5.
- Record
CVE-2026-100355- CVSS 3.1
- 3.1 Low
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:N/A:N - Weakness
- CWE-918
- Updated
- 2026-11-05
EUVDEUVD-2026-114058
Campfire is a web-based chat application. In version 1.4.4 and earlier, when a Campfire message contains a link, the server fetches it to build an OpenGraph unfurl preview. RestrictedHTTP::PrivateNetworkGuard relied on Ruby's IPAddr#private? `` IPAddr#loopback?, and IPAddr#link_local? predicates plus IPv4-mapped and IPv4-compatible checks, which do not cover several special-use ranges. An authenticated user can post a link to a hostname resolving to CGNAT 100.64.0.0/10, NAT64 64:ff9b::/96 or 64:ff9b:1::/48, or 6to4 2002::/16 to bypass the guard and cause server-side requests to internal network resources. The NAT64 and 6to4 ranges can embed an internal IPv4 target. Confidentiality impact is limited to returned OpenGraph metadata, and most internal endpoints return none. There is no integrity or availability impact. An initial fix was released in version 1.4.5.
- Record
EUVD-2026-114058- CVSS 3.1
- 3.1 Low
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:N/A:N - Updated
- 2026-11-05
NVD
Campfire is a web-based chat application. In version 1.4.4 and earlier, when a Campfire message contains a link, the server fetches it to build an OpenGraph unfurl preview. RestrictedHTTP::PrivateNetworkGuard relied on Ruby's IPAddr#private? `` IPAddr#loopback?, and IPAddr#link_local? predicates plus IPv4-mapped and IPv4-compatible checks, which do not cover several special-use ranges. An authenticated user can post a link to a hostname resolving to CGNAT 100.64.0.0/10, NAT64 64:ff9b::/96 or 64:ff9b:1::/48, or 6to4 2002::/16 to bypass the guard and cause server-side requests to internal network resources. The NAT64 and 6to4 ranges can embed an internal IPv4 target. Confidentiality impact is limited to returned OpenGraph metadata, and most internal endpoints return none. There is no integrity or availability impact. An initial fix was released in version 1.4.5.
- Record
CVE-2026-100355- CVSS 3.1
- 3.1 Low
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:N/A:N - Weakness
- CWE-918
- Updated
- 2026-11-05
OSV
Campfire vulnerable to SSRF via incomplete private-network denylist in the link-unfurl guard
Campfire is a web-based chat application. In version 1.4.4 and earlier, when a Campfire message contains a link, the server fetches it to build an OpenGraph unfurl preview. RestrictedHTTP::PrivateNetworkGuard relied on Ruby's IPAddr#private? `` IPAddr#loopback?, and IPAddr#link_local? predicates plus IPv4-mapped and IPv4-compatible checks, which do not cover several special-use ranges. An authenticated user can post a link to a hostname resolving to CGNAT 100.64.0.0/10, NAT64 64:ff9b::/96 or 64:ff9b:1::/48, or 6to4 2002::/16 to bypass the guard and cause server-side requests to internal network resources. The NAT64 and 6to4 ranges can embed an internal IPv4 target. Confidentiality impact is limited to returned OpenGraph metadata, and most internal endpoints return none. There is no integrity or availability impact. An initial fix was released in version 1.4.5.
- Record
CVE-2026-100355- CVSS 3.1
- 3.1 Low
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:N/A:N - Weakness
- CWE-918
- Updated
- 2026-11-07
Affected products
History
| Recorded | Changed | Sources |
|---|---|---|
| facts | EUVD | |
| first indexed | CVE List, EUVD, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2026-100355 is a low vulnerability (CVSS 3.1) in Basecamp Once-campfire, published October 30, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.28%, the 20th percentile. No source names a fixed version.
References
github.com/basecamp/once-campfire/security/advisories/GHSA-gjm7-g266-w3wj
nvd.nist.gov/vuln/detail/CVE-2026-100355