Forgejo 13.0.0 through 16.0.4, when "[federation] ENABLED = true" is set, has a spoofing issue that affects identity integrity but does not allow account takeover or content modification. It does not verify that the HTTP Signature on an incoming ActivityPub activity was produced by the key belonging to the actor named in the activity body. The signature verification in routers/api/v1/activitypub/reqsignature.go validates the request signature, but the inbox activity handlers subsequently read the acting identity from the attacker-controlled JSON body without binding it to the verified signing key. Additionally, the signed Digest header is not recomputed against the received request body. A remote attacker who hosts a single valid ActivityPub actor and keypair can therefore submit signature-valid activities attributed to any actor identity they name.

Forgejo before 16.0.4 allows use of restricted API tokens for unintended access to the "allow maintainer edit" feature.

node-forge through 1.4.0 fails to validate element count in nested DigestAlgorithm sequences during RSA PKCS#1 v1.5 signature verification. Attackers can embed garbage bytes inside the DigestAlgorithm sequence to forge valid signatures for arbitrary messages using low-exponent RSA keys. This is an incomplete fix for CVE-2026-33894.

A vulnerability was found in Forgejo up to 15.0.4. This issue affects the function net.LookupIP of the file services/migrations/allowlist/is_migrate_allowed.go of the component Repository Migration Handler. Performing a manipulation results in server-side request forgery. The attack can be initiated remotely. The exploit has been made public and could be used. The patch is named b313bb83f5ff22bcc0378e0e0ca7bbd58303f168. It is recommended to apply a patch to fix this issue. The project maintainer explains: "I don't intend to backport this to v15 or v16 as it is a breaking change."

Forgejo before 15.0.3 contains a stored cross-site scripting vulnerability that allows authenticated attackers to execute arbitrary JavaScript in other users' browsers by setting a full name containing an HTML payload and triggering an Actions run. When the DEFAULT_SHOW_FULL_NAME option is enabled, the run description is assembled server-side with the user's display name interpolated into an HTML string via a translation function that does not escape its arguments, and the frontend renders the result using a Vue v-html binding, causing script execution for any user who views the affected Actions run page.