CVE-2026-55430
Coder's subdomain workspace app routing trusts unauthenticated X-Forwarded-Host header, enabling cross-app data access
Coder allows organizations to provision remote development environments via Terraform. Prior to versions 2.29.7, 2.32.7, 2.33.8, and 2.34.2, the workspace app proxy resolves the target app from httpapi.RequestHost() which prefers the X-Forwarded-Host header over the real Host header. No middleware strips X-Forwarded-Host before routing and the header is not browser-forbidden so client-side JavaScript can set it on fetch() calls. Practical exploitation requires subdomain app routing (wildcard hostname) enabled, a victim who visits the attacker's shared app and a deployment whose upstream proxy does not strip X-Forwarded-Host. The fix in versions 2.29.7, 2.32.7, 2.33.8, and 2.34.2 trusts X-Forwarded-Host only from configured trusted proxies and otherwise resolves the routing host from the verified request host. As a workaround, place an upstream reverse proxy that strips or overwrites X-Forwarded-Host on untrusted requests.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- High
- Privileges needed
- Low
- User interaction
- Required
What an attacker can affect
- Confidentiality
- High
- Integrity
- None
- Availability
- None
Exploit likelihood
What each source reports
CVE List Score used
Coder's subdomain workspace app routing trusts unauthenticated X-Forwarded-Host header, enabling cross-app data access
Coder allows organizations to provision remote development environments via Terraform. Prior to versions 2.29.7, 2.32.7, 2.33.8, and 2.34.2, the workspace app proxy resolves the target app from httpapi.RequestHost() which prefers the X-Forwarded-Host header over the real Host header. No middleware strips X-Forwarded-Host before routing and the header is not browser-forbidden so client-side JavaScript can set it on fetch() calls. Practical exploitation requires subdomain app routing (wildcard hostname) enabled, a victim who visits the attacker's shared app and a deployment whose upstream proxy does not strip X-Forwarded-Host. The fix in versions 2.29.7, 2.32.7, 2.33.8, and 2.34.2 trusts X-Forwarded-Host only from configured trusted proxies and otherwise resolves the routing host from the verified request host. As a workaround, place an upstream reverse proxy that strips or overwrites X-Forwarded-Host on untrusted requests.
- Record
CVE-2026-55430- CVSS 3.1
- 5.8 Medium
CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:H/I:N/A:N - Weakness
- CWE-345, CWE-441
- Updated
- 2026-11-02
EUVDEUVD-2026-42136
Coder allows organizations to provision remote development environments via Terraform. Prior to versions 2.29.7, 2.32.7, 2.33.8, and 2.34.2, the workspace app proxy resolves the target app from httpapi.RequestHost() which prefers the X-Forwarded-Host header over the real Host header. No middleware strips X-Forwarded-Host before routing and the header is not browser-forbidden so client-side JavaScript can set it on fetch() calls. Practical exploitation requires subdomain app routing (wildcard hostname) enabled, a victim who visits the attacker's shared app and a deployment whose upstream proxy does not strip X-Forwarded-Host. The fix in versions 2.29.7, 2.32.7, 2.33.8, and 2.34.2 trusts X-Forwarded-Host only from configured trusted proxies and otherwise resolves the routing host from the verified request host. As a workaround, place an upstream reverse proxy that strips or overwrites X-Forwarded-Host on untrusted requests.
- Record
EUVD-2026-42136- CVSS 3.1
- 5.8 Medium
CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:H/I:N/A:N - Updated
- 2026-11-02
GitHub AdvisoriesGHSA-5g4w-3vw9-478w
Coder's subdomain workspace app routing trusts unauthenticated X-Forwarded-Host header, enabling cross-app data access
Summary
The workspace app proxy resolves the target app from httpapi.RequestHost() which prefers the X-Forwarded-Host header over the real Host header. No middleware strips X-Forwarded-Host before routing and the header is not browser-forbidden so client-side JavaScript can set it on fetch() calls.
Note: Practical exploitation requires subdomain app routing (wildcard hostname) enabled, a victim who visits the attacker's shared app and a deployment whose upstream proxy does not strip
X-Forwarded-Host.
Impact
App session cookies are scoped to the wildcard parent domain so the browser attaches them to any app subdomain. An attacker who controls a shared workspace app can serve JavaScript that sends same-site requests with a forged X-Forwarded-Host pointing at a victim's private app. The server routes by the attacker-controlled header but authorizes with the victim's cookie which lets the attacker read the victim's private app responses. Subdomain app routing must be enabled and no upstream proxy may strip X-Forwarded-Host.
Patches
The fix trusts X-Forwarded-Host only from configured trusted proxies and otherwise resolves the routing host from the verified request host.
The fix was backported to all supported release lines:
| Release line | Patched version | |---|---| | 2.34 | v2.34.2 | | 2.33 | v2.33.8 | | 2.32 | v2.32.7 | | 2.29 (ESR) | v2.29.17 |
Workarounds
Place an upstream reverse proxy that strips or overwrites X-Forwarded-Host on untrusted requests.
Resources
- Fix: #26204
Credits
Coder would like to thank Anthropic's Security Team (ANT-2026-22435) for independently disclosing this issue!
- Record
GHSA-5g4w-3vw9-478w- CVSS 3.1
- 5.8 Medium
CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:H/I:N/A:N - Weakness
- CWE-345, CWE-441
- Updated
- 2026-11-02
NVD
Coder allows organizations to provision remote development environments via Terraform. Prior to versions 2.29.7, 2.32.7, 2.33.8, and 2.34.2, the workspace app proxy resolves the target app from httpapi.RequestHost() which prefers the X-Forwarded-Host header over the real Host header. No middleware strips X-Forwarded-Host before routing and the header is not browser-forbidden so client-side JavaScript can set it on fetch() calls. Practical exploitation requires subdomain app routing (wildcard hostname) enabled, a victim who visits the attacker's shared app and a deployment whose upstream proxy does not strip X-Forwarded-Host. The fix in versions 2.29.7, 2.32.7, 2.33.8, and 2.34.2 trusts X-Forwarded-Host only from configured trusted proxies and otherwise resolves the routing host from the verified request host. As a workaround, place an upstream reverse proxy that strips or overwrites X-Forwarded-Host on untrusted requests.
- Record
CVE-2026-55430- CVSS 3.1
- 5.8 Medium
CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:H/I:N/A:N - CVSS 3.1
- 6.8 Medium
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:N/A:N - Weakness
- CWE-345, CWE-441
- Updated
- 2026-11-02
OSV
Coder's subdomain workspace app routing trusts unauthenticated X-Forwarded-Host header, enabling cross-app data access
Coder allows organizations to provision remote development environments via Terraform. Prior to versions 2.29.7, 2.32.7, 2.33.8, and 2.34.2, the workspace app proxy resolves the target app from httpapi.RequestHost() which prefers the X-Forwarded-Host header over the real Host header. No middleware strips X-Forwarded-Host before routing and the header is not browser-forbidden so client-side JavaScript can set it on fetch() calls. Practical exploitation requires subdomain app routing (wildcard hostname) enabled, a victim who visits the attacker's shared app and a deployment whose upstream proxy does not strip X-Forwarded-Host. The fix in versions 2.29.7, 2.32.7, 2.33.8, and 2.34.2 trusts X-Forwarded-Host only from configured trusted proxies and otherwise resolves the routing host from the verified request host. As a workaround, place an upstream reverse proxy that strips or overwrites X-Forwarded-Host on untrusted requests.
- Record
CVE-2026-55430- CVSS 3.1
- 5.8 Medium
CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:H/I:N/A:N - Weakness
- CWE-345, CWE-441
- Updated
- 2026-11-02
OSVGHSA-5g4w-3vw9-478w
Coder's subdomain workspace app routing trusts unauthenticated X-Forwarded-Host header, enabling cross-app data access
Summary
The workspace app proxy resolves the target app from httpapi.RequestHost() which prefers the X-Forwarded-Host header over the real Host header. No middleware strips X-Forwarded-Host before routing and the header is not browser-forbidden so client-side JavaScript can set it on fetch() calls.
Note: Practical exploitation requires subdomain app routing (wildcard hostname) enabled, a victim who visits the attacker's shared app and a deployment whose upstream proxy does not strip
X-Forwarded-Host.
Impact
App session cookies are scoped to the wildcard parent domain so the browser attaches them to any app subdomain. An attacker who controls a shared workspace app can serve JavaScript that sends same-site requests with a forged X-Forwarded-Host pointing at a victim's private app. The server routes by the attacker-controlled header but authorizes with the victim's cookie which lets the attacker read the victim's private app responses. Subdomain app routing must be enabled and no upstream proxy may strip X-Forwarded-Host.
Patches
The fix trusts X-Forwarded-Host only from configured trusted proxies and otherwise resolves the routing host from the verified request host.
The fix was backported to all supported release lines:
| Release line | Patched version | |---|---| | 2.34 | v2.34.2 | | 2.33 | v2.33.8 | | 2.32 | v2.32.7 | | 2.29 (ESR) | v2.29.17 |
Workarounds
Place an upstream reverse proxy that strips or overwrites X-Forwarded-Host on untrusted requests.
Resources
- Fix: #26204
Credits
Coder would like to thank Anthropic's Security Team (ANT-2026-22435) for independently disclosing this issue!
- Record
GHSA-5g4w-3vw9-478w- CVSS 3.1
- 5.8 Medium
CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:H/I:N/A:N - Weakness
- CWE-345, CWE-441
- Updated
- 2026-11-02
OSVGO-2026-5917 No score
Coder's subdomain workspace app routing trusts unauthenticated X-Forwarded-Host header, enabling cross-app data access in github.com/coder/coder
Coder's subdomain workspace app routing trusts unauthenticated X-Forwarded-Host header, enabling cross-app data access in github.com/coder/coder
- Record
GO-2026-5917- Updated
- 2026-11-02
OSVopenSUSE-SU-2026:21483-1 No score
Security update for govulncheck-vulndb
This update for govulncheck-vulndb fixes the following issues:
- Update to version 0.0.20260723T184607 2026-07-23T18:46:07Z (jsc#PED-11136).
Go CVE Numbering Authority IDs added or updated with aliases:
- GO-2026-4730 CVE-2026-33022 GHSA-cv4x-93xx-wgfj
- GO-2026-4761 CVE-2026-33211 GHSA-j5q5-j9gm-2w5c
- GO-2026-5102 CVE-2026-45021 GHSA-3vcp-chfh-f6r2
- GO-2026-5272 CVE-2026-40938 GHSA-94jr-7pqp-xhcq
- GO-2026-5486 CVE-2026-40924 GHSA-m2cx-gpqf-qf74
- GO-2026-5542 CVE-2026-40090 GHSA-pj97-4p9w-gx3q
- GO-2026-5630 CVE-2026-25542 GHSA-rmx9-2pp3-xhcr
- GO-2026-5643 CVE-2026-40923 GHSA-rx35-6rhx-7858
- GO-2026-5675 CVE-2026-41492 GHSA-vvf7-6rmr-m29q
- GO-2026-5711 CVE-2026-40161 GHSA-wjxp-xrpv-xpff
- GO-2026-5746 CVE-2026-41567 GHSA-x86f-5xw2-fm2r
- GO-2026-5749 CVE-2026-41328 GHSA-x92x-px7w-4gx4
- GO-2026-5837 CVE-2026-44840 GHSA-q2m9-6jp9-c6mc
- GO-2026-5929 CVE-2026-44342 GHSA-26v7-h57m-gh9m
- GO-2026-5930 CVE-2026-33655 GHSA-6qcr-qxgr-m7fv
- GO-2026-5933 GHSA-3g4q-2f67-2gvh
- GO-2026-5934 GHSA-59qp-cfj3-rp64
- GO-2026-5935 GHSA-7856-g3gv-9wq8
- GO-2026-5936 CVE-2026-53552 GHSA-26rh-24rg-j3vv
- GO-2026-5937 CVE-2026-53508 GHSA-2jcc-mxv7-p3f9
- GO-2026-5938 CVE-2026-53553 GHSA-4g5x-hcwm-82jw
- GO-2026-5939 CVE-2026-10517 GHSA-698x-9w2p-7vvp
- GO-2026-5940 CVE-2026-53572 GHSA-6w3m-4hhp-775q
- GO-2026-5941 CVE-2026-53487 GHSA-gvhc-wv3v-7pf8
- GO-2026-5942 CVE-2026-46600
- GO-2026-5944 CVE-2026-50197 GHSA-659f-rgp5-w4wf
- GO-2026-5945 CVE-2026-6815 GHSA-rmxx-v9rj-vpvg
- GO-2026-5946 CVE-2026-52831 GHSA-v5px-423j-pf7p
- GO-2026-5947 CVE-2026-53649 GHSA-xqhv-chqm-fhcc
- GO-2026-5948 CVE-2026-50554 GHSA-588f-fvcv-xhvf
- GO-2026-5949 CVE-2026-50553 GHSA-rqrh-8wpv-x7hh
- GO-2026-5950 CVE-2026-53602 GHSA-339v-266x-79xr
- GO-2026-5951 CVE-2026-10219 GHSA-6jm8-4fhr-5w64
- GO-2026-5952 CVE-2026-49834 GHSA-9vcr-p3rj-q5q6
- GO-2026-5953 CVE-2026-9094 GHSA-c9w5-qp6m-m395
- GO-2026-5956 CVE-2026-55252 GHSA-h5g6-xmh4-hc37
- GO-2026-5957 CVE-2026-54158 GHSA-5xfx-xj4h-5p7r
- GO-2026-5958 CVE-2026-54068 GHSA-gcm7-57gf-953c
- GO-2026-5959 CVE-2026-54072 GHSA-h29v-hj44-q8cv
- GO-2026-5961 CVE-2026-54069 GHSA-hvr9-72v2-fff3
- GO-2026-5962 CVE-2026-54088 GHSA-m93h-4hw7-5qcm
- GO-2026-5963 CVE-2026-54067 GHSA-mvjr-vv3c-w4qv
- GO-2026-5964 CVE-2026-54066 GHSA-p4m3-mgmm-c664
- GO-2026-5965 CVE-2026-54070 GHSA-w7cg-whh7-xp28
- GO-2026-5966 CVE-2026-54089 GHSA-xqp3-jq6g-x3qm
- GO-2026-5967 CVE-2026-50551 GHSA-56mp-4f3v-fgj2
- GO-2026-5968 CVE-2026-54174 GHSA-fpg8-7664-jc5q
- GO-2026-5969 GHSA-g936-7jqj-mwv8
- GO-2026-5970 CVE-2026-56852
- GO-2026-5973 CVE-2026-54250 GHSA-jxr7-mqhw-9p98
- GO-2026-5974 CVE-2026-44300 GHSA-wmj8-9953-vff5
- GO-2026-5975 CVE-2026-50018 GHSA-42j2-w334-qxw7
- GO-2026-5976 CVE-2026-50141 GHSA-g7mm-9vx7-jm7h
- GO-2026-5977 CVE-2026-50013 GHSA-qrh4-p6v4-mrfg
- GO-2026-5978 CVE-2026-50125 GHSA-qw5r-ppcg-f8rj
- GO-2026-5979 CVE-2026-50006 GHSA-xrcf-6jh3-ggvx
- GO-2026-5980 CVE-2026-50158 GHSA-2c7f-fxww-6w6c
- GO-2026-5981 GHSA-mqxv-9rm6-w8qc
- GO-2026-5982 GHSA-pqg7-v6wh-3pfp
- GO-2026-5984 CVE-2026-53604 GHSA-2p2f-px33-4vv5
- GO-2026-5985 GHSA-7rx3-5wx3-5v76
- GO-2026-5986 CVE-2026-61699 GHSA-cm26-5974-52h8
- GO-2026-5987 CVE-2026-55513 GHSA-g4x6-jcvr-9m3g
- GO-2026-5988 CVE-2026-54628 GHSA-hwrq-8wxh-q4xv
- GO-2026-5989 CVE-2026-55512 GHSA-m3cx-mwpg-32jg
- GO-2026-5990 CVE-2026-54629 GHSA-mf78-3rpf-r784
- GO-2026-5991 CVE-2026-53603 GHSA-q4vm-pq3q-8wgq
- GO-2026-5992 CVE-2026-61549 GHSA-qf34-295c-26v8
- GO-2026-5996 CVE-2026-54450 GHSA-pph6-vfjv-vpjw
- GO-2026-5997 CVE-2026-54452 GHSA-xgch-x3mx-cm3c
- GO-2026-5998 CVE-2026-54495 GHSA-398h-7f66-3h4p
- GO-2026-5999 CVE-2026-10814 GHSA-jh6h-v6mp-h22v
- GO-2026-6002 CVE-2026-58196 GHSA-pr64-jmmf-jp54
- GO-2026-6003 CVE-2026-53714 GHSA-22xc-xg2r-9j7v
- GO-2026-6004 CVE-2026-52833 GHSA-3v79-m2cg-89ww
- GO-2026-6005 CVE-2026-53715 GHSA-8fv2-88gg-hm7q
- GO-2026-6006 CVE-2026-53716 GHSA-cxpq-8v7q-cg56 *…
- Record
openSUSE-SU-2026:21483-1- Updated
- 2026-11-02
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
github.com/coder/coder/v2Go |
2.34.0 up to 2.34.2 | 2.34.2 |
github.com/coder/coder/v2Go |
2.33.0 up to 2.33.8 | 2.33.8 |
github.com/coder/coder/v2Go |
2.30.0 up to 2.32.7 | 2.32.7 |
github.com/coder/coder/v2Go |
before 2.29.17 | 2.29.17 |
github.com/coder/coderGo |
All versions | None known |
github.com/coder/coder/v2Go |
before 2.29.17, 2.30.0 up to 2.32.7, 2.33.0 up to 2.33.8, 2.34.0 up to 2.34.2 | 2.29.172.32.72.33.82.34.2 |
govulncheck-vulndbopenSUSE:Leap 16.0 From an advisory covering 1734 CVEs |
before 0.0.20260723T184607-160000.1.1 | 0.0.20260723T184607-160000.1.1 |
History
| Recorded | Changed | Sources |
|---|---|---|
| affected, facts | ||
| first indexed | CVE List, EUVD, GitHub Advisories, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2026-55430 is a medium vulnerability (CVSS 5.8) in Coder, published July 6, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.21%, the 11th percentile. Fixed in github.com/coder/coder/v2 2.34.2.
References
github.com/coder/coder/security/advisories/GHSA-5g4w-3vw9-478w
Show 194 moreShow less
nvd.nist.gov/vuln/detail/CVE-2026-55430
suse.com/security/cve/CVE-2016-11063
Left out here: 1,544 references and the rest of 1 source description. The JSON record has them.