Critical

Predictable UUID generation in Fiber v2 utils.UUIDv4()/UUID() on crypto/rand failure (Go <1.24)

IdentifiersCVE-2025-66630CWE-338· Use of Cryptographically Weak…

In Fiber v2 (github.com/gofiber/fiber/v2) prior to 2.52.11, the framework’s UUID generation helpers (vendored gofiber/utils UUIDv4()/UUID()) do not propagate errors from the underlying crypto/rand source on Go versions prior to 1.24. If the system CSPRNG cannot provide secure randomness and crypto/rand returns an error, Fiber’s UUID functions can silently produce predictable output (notably the all-zero UUID 00000000-0000-0000-0000-000000000000) without alerting application code. Because multiple Fiber v2 middleware components default to using utils.UUIDv4() (e.g., session middleware, CSRF, rate limiting, request-ID generation), this can cause security-critical identifiers/tokens to become guessable or collide, undermining authentication/authorization and integrity controls.

For your environment

Are you exposed to this one?

Mallory correlates every CVE against your assets, your vendors, and active adversary campaigns. Know which vulnerabilities matter for you, not just which ones are loud.

Start free trial

ANALYST BRIEF

Impact, mitigation & remediation

What it means. What to do now. Patch path, mitigations, and the assume-compromise checklist.

Impact

What an attacker gets, and what they’ve been doing with it.

Predictable or repeated UUIDs can enable session fixation/hijacking (impersonation without credential theft) when used as session IDs, CSRF token forgery/bypass when used for CSRF secrets/tokens, and token/identifier prediction for any authentication or authorization mechanism derived from these UUIDs. Collisions (e.g., many users receiving the same all-zero UUID) can also collapse key-based state (session stores, rate limiters, request IDs) onto a single key, causing overwrites, audit/trace ambiguity, and potential denial-of-service or state corruption.

Mitigation

If you can’t patch tonight, do this now.

Ensure the deployment environment reliably provides system randomness (e.g., /dev/urandom or platform equivalent) and avoid/review restricted environments that can break entropy access (containers, sandboxes, chroots/jails, embedded/misconfigured systems). Configure Fiber middleware to avoid default UUID generation for security-critical identifiers (sessions/CSRF/request IDs/rate-limit keys) and use an alternative token/UUID generator that surfaces entropy failures. Monitor/review logs and telemetry for anomalous patterns such as repeated identical session IDs/request IDs (including the all-zero UUID), which may indicate entropy failure and/or exploitation attempts.

Remediation

Patch, then assume compromise.

Upgrade Fiber v2 to 2.52.11 (fixed). Where feasible, run the application on Go 1.24+ (where crypto/rand failure behavior is described as blocking or panicking rather than returning an error). If upgrading is not immediately possible, replace/override usage of Fiber’s utils.UUIDv4()/UUID() in security-sensitive paths with a generator that fails closed (returns an error) rather than silently emitting predictable identifiers.

PUBLIC EXPLOITS

Exploits

No public exploits tracked yet. Mallory keeps watching.

VALID 0 / 0 TOTALView more in app

No public exploit code observed for this vulnerability.

EXPOSURE SURFACE

Affected products & vendors

Products and vendors Mallory has correlated with this vulnerability. Open in Mallory to drill down to specific CPE configurations and version ranges.

VendorProductType

GofiberFiberapplication

Vendor-confirmed product mapping. Mallory continuously reconciles this list against your asset inventory.

ACTIVITY FEED

Recent activity

4 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.

4 SOURCESView more in app

the hacker newsNews

Feb 16, 2026

Weekly Recap: Outlook Add-Ins Hijack, 0-Day Patches, Wormable Botnet & AI Malware

Unknown (listed as a trending CVE for Fiber v2 without details in the provided content).

cyber security newsNews

Feb 11, 2026

Critical UUID Flaw in Fiber v2 on Go 1.24+ Enables Session Hijacking, CSRF Bypass, and Zero-ID DoS Risk

A critical weakness in Fiber v2’s UUID generation where, on RNG failure, security-critical UUIDs (sessions, CSRF tokens, auth tokens) can silently become a predictable all-zero UUID, enabling session hijacking, security bypass, and potential denial of service via key collisions.

What this page doesn’t show

The version that knows your environment.

This page is what’s public. Mallory adds the parts that aren’t: which of your assets are affected, which adversaries are exploiting it right now, which detections to deploy, and what to do tonight.

Start free trial

Exposure mapping

Query your assets running an affected version, and investigate the blast radius.

Threat actor evidence

Every observed campaign linking this CVE to a named adversary.

Associated malware

Malware families riding this exploit, with evidence and IOCs.

Detection signatures

YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.

Vendor-by-vendor mapping

Cross-references every affected SKU, including bundled OEM variants.

Social activity2