CVE-2025-48865
published 2025-05-30CVE-2025-48865: Fabio is an HTTP(S) and TCP router for deploying applications managed by consul. Prior to version 1.6.6, Fabio allows clients to remove X-Forwarded headers…
PriorityP352critical9.1CVSS 3.1
AVNACLPRNUINSUCHIHAN
EPSS
0.51%
39.6th percentile
Fabio is an HTTP(S) and TCP router for deploying applications managed by consul. Prior to version 1.6.6, Fabio allows clients to remove X-Forwarded headers (except X-Forwarded-For) due to a vulnerability in how it processes hop-by-hop headers. Fabio adds HTTP headers like X-Forwarded-Host and X-Forwarded-Port when routing requests to backend applications. Since the receiving application should trust these headers, allowing HTTP clients to remove or modify them creates potential security vulnerabilities. Some of these custom headers can be removed and, in certain cases, manipulated. The attack relies on the behavior that headers can be defined as hop-by-hop via the HTTP Connection header. This issue has been patched in version 1.6.6.
Affected
2 ranges
| Vendor | Product | Version range | Fixed in |
|---|---|---|---|
| fabiolb | fabio | < 1.6.6 | 1.6.6 |
| github.com | fabiolb_fabio | >= 0 < 1.6.6 | 1.6.6 |
CVSS provenance
nvdv3.19.1CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
ghsa9.8CRITICAL
osv9.8CRITICAL
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OSV
Fabio allows HTTP clients to manipulate custom headers it adds in github.com/fabiolb/fabio
osv·2025-06-03
CVE-2025-48865 Fabio allows HTTP clients to manipulate custom headers it adds in github.com/fabiolb/fabio
Fabio allows HTTP clients to manipulate custom headers it adds in github.com/fabiolb/fabio
Fabio allows HTTP clients to manipulate custom headers it adds in github.com/fabiolb/fabio
GHSA
Fabio allows HTTP clients to manipulate custom headers it adds
ghsa·2025-05-29·CVSS 9.8
CVE-2025-48865 [CRITICAL] CWE-345 Fabio allows HTTP clients to manipulate custom headers it adds
Fabio allows HTTP clients to manipulate custom headers it adds
### Summary
Fabio allows clients to remove X-Forwarded headers (except X-Forwarded-For) due to a vulnerability in how it processes hop-by-hop headers.
Fabio adds HTTP headers like X-Forwarded-Host and X-Forwarded-Port when routing requests to backend applications. Since the receiving application should trust these headers, allowing HTTP clients to remove or modify them creates potential security vulnerabilities.
However, it was found that some of these custom headers can indeed be removed and, in certain cases, manipulated. The attack relies on the behavior that headers can be defined as hop-by-hop via the HTTP Connection header. By setting the following connection header, the X-Forwarded-Host header can, for example, be rem
OSV
Fabio allows HTTP clients to manipulate custom headers it adds
osv·2025-05-29·CVSS 9.8
CVE-2025-48865 [CRITICAL] Fabio allows HTTP clients to manipulate custom headers it adds
Fabio allows HTTP clients to manipulate custom headers it adds
### Summary
Fabio allows clients to remove X-Forwarded headers (except X-Forwarded-For) due to a vulnerability in how it processes hop-by-hop headers.
Fabio adds HTTP headers like X-Forwarded-Host and X-Forwarded-Port when routing requests to backend applications. Since the receiving application should trust these headers, allowing HTTP clients to remove or modify them creates potential security vulnerabilities.
However, it was found that some of these custom headers can indeed be removed and, in certain cases, manipulated. The attack relies on the behavior that headers can be defined as hop-by-hop via the HTTP Connection header. By setting the following connection header, the X-Forwarded-Host header can, for example, be rem
No detection rules found.
No public exploits indexed.
No writeups or analysis indexed.
2025-05-30
Published