# CVE-2026-49478: Fulcio has OIDC Discovery Redirect Following Allows SSRF and JWKS Substitution for Meta-Issuer Paths, with Kubernetes Service-Account Token Leakage > A malicious OIDC issuer can trigger SSRF and leak Kubernetes ServiceAccount tokens by exploiting improper redirect handling in Fulcio. - **Severity:** High 8.7 (`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:N`) - **Exploited in the wild:** Not known - **Login needed:** Not needed - **Attackable:** Over the internet - **Victim action needed:** Not needed - **Fix available:** Yes - **Published:** 13 Aug 2026 - **Updated:** 15 Aug 2026 - **Also known as:** CLEANSTART-2026-IH01456, DEBIAN-CVE-2026-49478, GHSA-f5mr-q85p-6hh6, GO-2026-5853, MINI-28x7-4j7x-cppv, MINI-439j-4486-x5fp, MINI-4xjc-3568-mmcg, MINI-52mv-fwp9-55r8, MINI-58pj-485r-65jh, MINI-5998-hh26-r6v6, MINI-5gpm-jcpc-mx6g, MINI-5v8x-5fmm-jc4g, MINI-65qv-qr7f-wgwh, MINI-6hfm-r574-gxrw, MINI-74fc-r4fv-fwh8, MINI-7g4w-f4g4-8w9x, MINI-866f-hr64-v57g, MINI-86fp-jqgm-rc57, MINI-8fqh-rpc8-f7xc, MINI-92p9-q5gf-ccrq, MINI-9phf-5q8x-8j9c, MINI-f82w-8vrw-h993, MINI-fh7v-6m9f-rxrx, MINI-gg25-89mv-7cr3, MINI-ghvq-cm48-g2xq, MINI-h2w9-h8p9-pm97, MINI-h9v7-g9m8-g8qr, MINI-hfw6-6p2r-f3fp, MINI-hm2g-v4jh-c7ch, MINI-j6xj-wmfg-6ggg, MINI-jmj9-9wpp-mpwm, MINI-m5gq-6r9h-p4g2, MINI-m6x6-jfjv-7c68, MINI-mfpm-hpjh-j9hg, MINI-mh3g-jhx3-h92c, MINI-mhqh-prv3-857r, MINI-mhw8-m424-4gcc, MINI-p8fp-xrg7-3437, MINI-pj5f-chpx-6xx2, MINI-pjjf-6xvw-4vw3, MINI-q89m-gm3m-gmhh, MINI-r39h-52w6-w3x6, MINI-rgf3-qm9h-x3m8, MINI-v7r7-wx8x-v629, MINI-w2xf-vxqp-fg69, MINI-wm33-cfr5-8r8q, MINI-x2f8-638x-98v8, MINI-x7c3-9j46-8v68, MINI-xc4j-w796-4hfg, MINI-xff9-j5w5-6c4f, UBUNTU-CVE-2026-49478 ## What is CVE-2026-49478? CVE-2026-49478 is a high-severity server-side request forgery vulnerability in sigstore fulcio, published on 13 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim. ### Official description Fulcio is a certificate authority for issuing code signing certificates for an OpenID Connect (OIDC) identity. Versions through 1.8.5 improperly follow cross-host redirects and attach Kubernetes ServiceAccount tokens during OIDC discovery, allowing a malicious or compromised issuer to perform blind SSRF, substitute and cache malicious JWKS keys, or disclose ServiceAccount tokens to external hosts. Version 1.8.6 blocks cross-host redirects, restricts token injection, and restricts local token loading. No known workarounds are available. Weakness: CWE-918 (Server-Side Request Forgery) ## Which versions are affected by CVE-2026-49478? 3 open source packages ship an affected version, including github.com/sigstore/fulcio. | Package | Ecosystem | Affected | Fixed in | | --- | --- | --- | --- | | `github.com/sigstore/fulcio` | Go | All versions | 1.8.6 | | `github.com/sigstore/fulcio` | Go | All versions | 1.8.6 | | `github.com/sigstore/fulcio` | Go | All versions | 1.8.6 | ## How do I fix CVE-2026-49478? Upgrade github.com/sigstore/fulcio to 1.8.6 or later. ## Is CVE-2026-49478 being exploited? There is no known exploitation of CVE-2026-49478 in the wild and no public exploit code. ## Fix prompt for AI coding agents ```text Check this codebase for CVE-2026-49478 and fix it if it is affected. What it is: CVE-2026-49478 is a high-severity server-side request forgery vulnerability in sigstore fulcio, published on 13 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim. Exploitation: There is no known exploitation of CVE-2026-49478 in the wild and no public exploit code. Affected packages and fixed versions: - github.com/sigstore/fulcio (Go): affected all versions; fixed in 1.8.6 - github.com/sigstore/fulcio (Go): affected all versions; fixed in 1.8.6 - github.com/sigstore/fulcio (Go): affected all versions; fixed in 1.8.6 Task: 1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies. 2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it. 3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead. 4. Run the tests and summarise what changed and why. 5. If nothing in the project is affected, say so and change nothing. Reference: https://insights.sbomify.com/CVE-2026-49478/ (Markdown: https://insights.sbomify.com/CVE-2026-49478/index.md) ``` ## Sources - CVE record: https://www.cve.org/CVERecord?id=CVE-2026-49478 - NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-49478 - OSV: https://osv.dev/vulnerability/CVE-2026-49478 --- From sbomify Insights: https://insights.sbomify.com/CVE-2026-49478/ Summaries are generated and may contain mistakes; the official description above is the record.