Fiber: CORS wildcard origins matched without a dot boundary, allowing credentialed cross-origin reads
cve-program · CVE-2026-119285
PublishedFiber is an Express inspired web framework written in Go. From 2.52.1 until 2.52.3, the CORS middleware's validateDomain wildcard matcher in middleware/cors/utils.go strips the scheme and checks only a host suffix without requiring a dot boundary. An application configured with a wildcard-subdomain AllowOrigins value and AllowCredentials enabled can reflect an unrelated attacker-controlled origin whose host merely ends with the configured base domain. A user who visits that origin can expose authenticated cross-origin responses to the attacker's page; empty-label origins and later comma-space parsing hardening are outside this advisory. This issue is fixed in version 2.52.3.
Read the publisher's advisoryeuvd · EUVD-2026-113402
PublishedFiber is an Express inspired web framework written in Go. From 2.52.1 until 2.52.3, the CORS middleware's validateDomain wildcard matcher in middleware/cors/utils.go strips the scheme and checks only a host suffix without requiring a dot boundary. An application configured with a wildcard-subdomain AllowOrigins value and AllowCredentials enabled can reflect an unrelated attacker-controlled origin whose host merely ends with the configured base domain. A user who visits that origin can expose authenticated cross-origin responses to the attacker's page; empty-label origins and later comma-space parsing hardening are outside this advisory. This issue is fixed in version 2.52.3.
Read the publisher's advisorynvd · CVE-2026-119285
PublishedFiber is an Express inspired web framework written in Go. From 2.52.1 until 2.52.3, the CORS middleware's validateDomain wildcard matcher in middleware/cors/utils.go strips the scheme and checks only a host suffix without requiring a dot boundary. An application configured with a wildcard-subdomain AllowOrigins value and AllowCredentials enabled can reflect an unrelated attacker-controlled origin whose host merely ends with the configured base domain. A user who visits that origin can expose authenticated cross-origin responses to the attacker's page; empty-label origins and later comma-space parsing hardening are outside this advisory. This issue is fixed in version 2.52.3.
Read the publisher's advisoryosv · GHSA-g5jq-qmqr-qrwf
Published### Summary In v2.52.1 and v2.52.2 the CORS middleware matched a wildcard origin such as `https://*.example.com` by suffix only, without a dot boundary and without comparing the scheme. Any origin whose host ends with the base domain, for example `https://evil-example.com` or `http://notexample.com`, was reflected in `Access-Control-Allow-Origin`, together with `Access-Control-Allow-Credentials: true` when `AllowCredentials` is enabled. v2.52.3 replaced the matcher (#2915) and is not affected. The report was filed against v2.52.15, where the dot boundary holds; see "Other versions" below. ### Details v2.52.1 introduced `validateDomain` in `middleware/cors/utils.go` (f0cd3b44, part of the fix for GHSA-fmg4-x8pw-hjhg). It strips scheme and port from both sides and then checks only the suffix, with `trimmedPattern = "example.com"`, so the character before the suffix is never checked: ```go if strings.HasPrefix(normalizedPattern, "*.") { trimmedPattern := normalizedPattern[2:] if strings.HasSuffix(normalizedDomain, trimmedPattern) { if normalizedDomain != trimmedPattern { if strings.TrimSuffix(normalizedDomain, trimmedPattern) != "" { return true } } } } ``` v2.52.3 (1aac6f61, #2915) replaced it with a scheme-aware prefix/suffix split that keeps the leading dot in the suffix (`.example.com`). ### Proof of concept ```go app := fiber.New() app.Use(cors.New(cors.Config{ AllowOrigins: "https://*.example.com", AllowCredentials: true, })) app.Get("/", func(c *fiber.Ctx) error { return c.SendString("secret") }) ``` Request with `Origin: https://evil-example.com`, as a GET and as a preflight (`OPTIONS` with `Access-Control-Request-Method: GET`): | Version | `https://evil-example.com` | `http://evil-example.com` | |---|---|---| | v2.52.0 | not allowed | not allowed | | v2.52.1, v2.52.2 | reflected, `Access-Control-Allow-Credentials: true` | reflected, `Access-Control-Allow-Credentials: true` | | v2.52.3 to v2.52.16 | not allowed | not allowed | ### Impact An app that configures a wildcard-subdomain `AllowOrigins` with `AllowCredentials: true` lets any page on a domain that ends with the base domain (for example `notexample.com` for `*.example.com`) read authenticated responses cross-origin. Fixed in v2.52.3; upgrade to the latest v2 release. ### Other versions All v2 releases before v2.52.16 also accepted origins with empty labels (`https://.example.com`, `https://a..example.com`), and v2.52.3 to v2.52.15 mis-parsed a wildcard entry after a comma and a space (`"https://a.com, https://*.example.com"`). No registrable domain produces such an origin, so these are hardening rather than part of this advisory. They are fixed in v2.52.16 (#4792).
Read the publisher's advisoryosv · GO-2026-6896
PublishedFiber: CORS wildcard origins matched without a dot boundary, allowing credentialed cross-origin reads in github.com/gofiber/fiber
Read the publisher's advisoryAffected versions, risk and source history
Exploitation and risk
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cve-program · CVE-2026-119285
PublishedFiber: CORS wildcard origins matched without a dot boundary, allowing credentialed cross-origin reads
Fiber is an Express inspired web framework written in Go. From 2.52.1 until 2.52.3, the CORS middleware's validateDomain wildcard matcher in middleware/cors/utils.go strips the scheme and checks only a host suffix without requiring a dot boundary. An application configured with a wildcard-subdomain AllowOrigins value and AllowCredentials enabled can reflect an unrelated attacker-controlled origin whose host merely ends with the configured base domain. A user who visits that origin can expose authenticated cross-origin responses to the attacker's page; empty-label origins and later comma-space parsing hardening are outside this advisory. This issue is fixed in version 2.52.3.
- Source published
- 29 Oct 2026 21:36:02 UTC
- Source modified
- 4 Nov 2026 01:55:09 UTC
- Saved here
- 4 Nov 2026 02:57:16 UTC
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- CVE Program Terms of Use
Original source record · Cite this exact observation · Complete original publisher JSON
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CVSS 3.1 · 5.9 CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:L/A:N
euvd · EUVD-2026-113402
PublishedFiber is an Express inspired web framework written in Go. From 2.52.1 until 2.52.3, the CORS middleware's validateDomain wildcard matcher in middleware/cors/utils.go strips the scheme and checks only a host suffix without requiring a dot bo…
Fiber is an Express inspired web framework written in Go. From 2.52.1 until 2.52.3, the CORS middleware's validateDomain wildcard matcher in middleware/cors/utils.go strips the scheme and checks only a host suffix without requiring a dot boundary. An application configured with a wildcard-subdomain AllowOrigins value and AllowCredentials enabled can reflect an unrelated attacker-controlled origin whose host merely ends with the configured base domain. A user who visits that origin can expose authenticated cross-origin responses to the attacker's page; empty-label origins and later comma-space parsing hardening are outside this advisory. This issue is fixed in version 2.52.3.
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datePublished: Oct 29, 2026, 9:36:02 PM
dateUpdated: Nov 4, 2026, 1:55:09 AM
- Source published
- Oct 29, 2026, 9:36:02 PM (timezone not stated)
- Source modified
- Nov 4, 2026, 1:55:09 AM (timezone not stated)
- Saved here
- 14 Nov 2026 07:10:53 UTC
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- ENISA EUVD · source terms and attribution apply
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EUVD CVSS 3.1 · 5.9 CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:L/A:N
nvd · CVE-2026-119285
PublishedFiber is an Express inspired web framework written in Go. From 2.52.1 until 2.52.3, the CORS middleware's validateDomain wildcard matcher in middleware/cors/utils.go strips the scheme and checks only a host suffix without requiring a dot bo…
Fiber is an Express inspired web framework written in Go. From 2.52.1 until 2.52.3, the CORS middleware's validateDomain wildcard matcher in middleware/cors/utils.go strips the scheme and checks only a host suffix without requiring a dot boundary. An application configured with a wildcard-subdomain AllowOrigins value and AllowCredentials enabled can reflect an unrelated attacker-controlled origin whose host merely ends with the configured base domain. A user who visits that origin can expose authenticated cross-origin responses to the attacker's page; empty-label origins and later comma-space parsing hardening are outside this advisory. This issue is fixed in version 2.52.3.
Additional publisher context
NVD analysis and CPE criteria are source context, not proof that a package or your environment is affected. Complete affected data, logical configurations and SSVC are retained in the original JSON.
Source analysis status: Awaiting Analysis
Weakness classifications: CWE-346 · CWE-942
Original publisher date fields
published: 2026-10-29T22:17:01.367
lastModified: 2026-11-04T02:17:19.083
- Source published
- 29 Oct 2026 22:17:01 UTC
- Source modified
- 4 Nov 2026 02:17:19 UTC
- Saved here
- 6 Nov 2026 01:43:49 UTC
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- NIST NVD usage terms; underlying source attribution retained
Original source record · Cite this exact observation · Complete original publisher JSON
Source: nvd · NIST NVD usage terms; underlying source attribution retained. The publisher's wording is preserved. ChangeIntel groups the information and labels changes. The JSON record includes additional source fields.
CVSS 3.1 · [email protected] · Secondary · 5.9 CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:L/A:N
osv · GHSA-g5jq-qmqr-qrwf
PublishedFiber: CORS wildcard origins matched without a dot boundary, allowing credentialed cross-origin reads
### Summary In v2.52.1 and v2.52.2 the CORS middleware matched a wildcard origin such as `https://*.example.com` by suffix only, without a dot boundary and without comparing the scheme. Any origin whose host ends with the base domain, for example `https://evil-example.com` or `http://notexample.com`, was reflected in `Access-Control-Allow-Origin`, together with `Access-Control-Allow-Credentials: true` when `AllowCredentials` is enabled. v2.52.3 replaced the matcher (#2915) and is not affected. The report was filed against v2.52.15, where the dot boundary holds; see "Other versions" below. ### Details v2.52.1 introduced `validateDomain` in `middleware/cors/utils.go` (f0cd3b44, part of the fix for GHSA-fmg4-x8pw-hjhg). It strips scheme and port from both sides and then checks only the suffix, with `trimmedPattern = "example.com"`, so the character before the suffix is never checked: ```go if strings.HasPrefix(normalizedPattern, "*.") { trimmedPattern := normalizedPattern[2:] if strings.HasSuffix(normalizedDomain, trimmedPattern) { if normalizedDomain != trimmedPattern { if strings.TrimSuffix(normalizedDomain, trimmedPattern) != "" { return true } } } } ``` v2.52.3 (1aac6f61, #2915) replaced it with a scheme-aware prefix/suffix split that keeps the leading dot in the suffix (`.example.com`). ### Proof of concept ```go app := fiber.New() app.Use(cors.New(cors.Config{ AllowOrigins: "https://*.example.com", AllowCredentials: true, })) app.Get("/", func(c *fiber.Ctx) error { return c.SendString("secret") }) ``` Request with `Origin: https://evil-example.com`, as a GET and as a preflight (`OPTIONS` with `Access-Control-Request-Method: GET`): | Version | `https://evil-example.com` | `http://evil-example.com` | |---|---|---| | v2.52.0 | not allowed | not allowed | | v2.52.1, v2.52.2 | reflected, `Access-Control-Allow-Credentials: true` | reflected, `Access-Control-Allow-Credentials: true` | | v2.52.3 to v2.52.16 | not allowed | not allowed | ### Impact An app that configures a wildcard-subdomain `AllowOrigins` with `AllowCredentials: true` lets any page on a domain that ends with the base domain (for example `notexample.com` for `*.example.com`) read authenticated responses cross-origin. Fixed in v2.52.3; upgrade to the latest v2 release. ### Other versions All v2 releases before v2.52.16 also accepted origins with empty labels (`https://.example.com`, `https://a..example.com`), and v2.52.3 to v2.52.15 mis-parsed a wildcard entry after a comma and a space (`"https://a.com, https://*.example.com"`). No registrable domain produces such an origin, so these are hardening rather than part of this advisory. They are fixed in v2.52.16 (#4792).
- Source published
- 30 Oct 2026 22:58:05 UTC
- Source modified
- 5 Nov 2026 23:25:41 UTC
- Saved here
- 5 Nov 2026 23:38:32 UTC
- Source terms
- GitHub Advisory Database · CC-BY-4.0
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CVSS_V3 · CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:L/A:N
Publisher rating · MODERATE
osv · GO-2026-6896
PublishedFiber: CORS wildcard origins matched without a dot boundary, allowing credentialed cross-origin reads in github.com/gofiber/fiber
Fiber: CORS wildcard origins matched without a dot boundary, allowing credentialed cross-origin reads in github.com/gofiber/fiber
- Source published
- 5 Nov 2026 22:55:03 UTC
- Source modified
- 5 Nov 2026 23:15:16 UTC
- Saved here
- 5 Nov 2026 23:38:32 UTC
- Source terms
- OSV · upstream source license applies
Original source record · Cite this exact observation · Complete original publisher JSON
Source: osv · OSV · upstream source license applies. The publisher's wording is preserved. ChangeIntel groups the information and labels changes. The JSON record includes additional source fields.