Fiber is a web framework for Go. Prior to 2.52.12 and 3.1.0, Cross-Site Scripting vulnerability in Go Fiber allows a remote attacker to inject arbitrary HTML/JavaScript by supplying Accept: text/html on any request whose handler passes attacker-influenced data to the AutoFormat() feature. The developer opts into content negotiation by calling AutoFormat(), but does not opt into raw HTML emission for a particular request; Fiber chooses that branch from attacker-controlled Accept. The html branch is the sole outlier in a method whose name (AutoFormat) and symmetrical structure actively telegraph "safe, format-agnostic reply." This vulnerability is fixed in 2.52.12 and 3.1.0.
CVSS Score
5.3
EPSS Score
0.0
Published
2026-05-11
Fiber is a web framework for Go. In github.com/gofiber/fiber/v3 versions through 3.1.0, the default key generator in the cache middleware uses only the request path and does not include the query string. As a result, requests for the same path with different query parameters can share a cache key and receive the wrong cached response. This can cause response mix-up for query-dependent endpoints and may expose data intended for a different request. This issue is fixed after version 3.1.0.
CVSS Score
6.5
EPSS Score
0.0
Published
2026-05-05
Fiber is an Express inspired web framework written in Go. A Path Traversal (CWE-22) vulnerability in Fiber allows a remote attacker to bypass the static middleware sanitizer and read arbitrary files on the server file system on Windows. This affects Fiber v3 through version 3.0.0. This has been patched in Fiber v3 version 3.1.0.
CVSS Score
7.7
EPSS Score
0.0
Published
2026-02-24
Fiber is an Express inspired web framework written in Go. In versions on the v3 branch prior to 3.1.0, the use of the `fiber_flash` cookie can force an unbounded allocation on any server. A crafted 10-character cookie value triggers an attempt to allocate up to 85GB of memory via unvalidated msgpack deserialization. No authentication is required. Every GoFiber v3 endpoint is affected regardless of whether the application uses flash messages. Version 3.1.0 fixes the issue.
CVSS Score
7.5
EPSS Score
0.001
Published
2026-02-24
Fiber is an Express inspired web framework written in Go. A denial of service vulnerability exists in Fiber v2 and v3 that allows remote attackers to crash the application by sending requests to routes with more than 30 parameters. The vulnerability results from missing validation during route registration combined with an unbounded array write during request matching. Version 2.52.12 patches the issue in the v2 branch and 3.1.0 patches the issue in the v3 branch.
CVSS Score
5.5
EPSS Score
0.001
Published
2026-02-24
Fiber is an Express inspired web framework written in Go. Before 2.52.11, on Go versions prior to 1.24, the underlying crypto/rand implementation can return an error if secure randomness cannot be obtained. Because no error is returned by the Fiber v2 UUID functions, application code may unknowingly rely on predictable, repeated, or low-entropy identifiers in security-critical pathways. This is especially impactful because many Fiber v2 middleware components (session middleware, CSRF, rate limiting, request-ID generation, etc.) default to using utils.UUIDv4(). This vulnerability is fixed in 2.52.11.
CVSS Score
9.2
EPSS Score
0.0
Published
2026-02-09
Fiber is an Express inspired web framework written in Go. In versions 2.52.8 and below, when using Fiber's Ctx.BodyParser to parse form data containing a large numeric key that represents a slice index (e.g., test.18446744073704), the application crashes due to an out-of-bounds slice allocation in the underlying schema decoder. The root cause is that the decoder attempts to allocate a slice of length idx + 1 without validating whether the index is within a safe or reasonable range. If the idx is excessively large, this leads to an integer overflow or memory exhaustion, causing a panic or crash. This is fixed in version 2.52.9.
CVSS Score
8.7
EPSS Score
0.004
Published
2025-08-06
Fiber is an Express-inspired web framework written in Go. Starting in version 2.52.6 and prior to version 2.52.7, `fiber.Ctx.BodyParser` can map flat data to nested slices using `key[idx]value` syntax, but when idx is negative, it causes a panic instead of returning an error stating it cannot process the data. Since this data is user-provided, this could lead to denial of service for anyone relying on this `fiber.Ctx.BodyParser` functionality. Version 2.52.7 fixes the issue.
CVSS Score
7.7
EPSS Score
0.005
Published
2025-05-22
Fiber is an Express-inspired web framework written in Go A vulnerability present in versions prior to 2.52.5 is a session middleware issue in GoFiber versions 2 and above. This vulnerability allows users to supply their own session_id value, resulting in the creation of a session with that key. If a website relies on the mere presence of a session for security purposes, this can lead to significant security risks, including unauthorized access and session fixation attacks. All users utilizing GoFiber's session middleware in the affected versions are impacted. The issue has been addressed in version 2.52.5. Users are strongly encouraged to upgrade to version 2.52.5 or higher to mitigate this vulnerability. Users who are unable to upgrade immediately can apply the following workarounds to reduce the risk: Either implement additional validation to ensure session IDs are not supplied by the user and are securely generated by the server, or regularly rotate session IDs and enforce strict session expiration policies.
CVSS Score
10.0
EPSS Score
0.003
Published
2024-07-01
Fiber is a web framework written in go. Prior to version 2.52.1, the CORS middleware allows for insecure configurations that could potentially expose the application to multiple CORS-related vulnerabilities. Specifically, it allows setting the Access-Control-Allow-Origin header to a wildcard (`*`) while also having the Access-Control-Allow-Credentials set to true, which goes against recommended security best practices. The impact of this misconfiguration is high as it can lead to unauthorized access to sensitive user data and expose the system to various types of attacks listed in the PortSwigger article linked in the references. Version 2.52.1 contains a patch for this issue. As a workaround, users may manually validate the CORS configurations in their implementation to ensure that they do not allow a wildcard origin when credentials are enabled. The browser fetch api, as well as browsers and utilities that enforce CORS policies, are not affected by this.
CVSS Score
9.4
EPSS Score
0.005
Published
2024-02-21
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