{"id":"CVE-2026-39819","aliases":["GO-2026-4978","BIT-golang-2026-39819"],"title":"Invoking \"go bug\" follows symlinks in predictable temporary filenames in cmd/go","summary":"Invoking \"go bug\" follows symlinks in predictable temporary filenames in cmd/go","severity":"medium","cvss":4.4,"cvssVector":"CVSS:3.1/AV:L/AC:H/PR:L/UI:R/S:U/C:N/I:H/A:N","vendor":"toolchain","product":"toolchain","ecosystem":"go","affected":["toolchain >= 1.26.0-0, < 1.26.3"],"patched":["toolchain 1.26.3"],"published":"2026-05-07","updated":"2026-09-22","sourceUpdated":"2026-09-22T10:41:48.065334746Z","source":"OSV","sourceUrl":"https://osv.dev/vulnerability/GO-2026-4978","references":[{"url":"https://go.dev/issue/78584"},{"url":"https://go.dev/cl/763882"},{"url":"https://groups.google.com/g/golang-announce/c/qcCIEXso47M"},{"url":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-39819.json"},{"url":"https://access.redhat.com/security/cve/CVE-2026-39819"},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2467813"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-39819"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-39819"},{"url":"https://pkg.go.dev/vuln/GO-2026-4978"},{"url":"https://access.redhat.com/errata/RHSA-2026:49702"},{"url":"https://access.redhat.com/errata/RHSA-2026:22120"},{"url":"https://access.redhat.com/errata/RHSA-2026:22112"},{"url":"https://access.redhat.com/errata/RHSA-2026:61253"},{"url":"https://access.redhat.com/errata/RHSA-2026:57649"},{"url":"https://access.redhat.com/errata/RHSA-2026:49712"},{"url":"https://access.redhat.com/errata/RHSA-2026:22121"},{"url":"https://access.redhat.com/errata/RHSA-2026:62391"},{"url":"https://access.redhat.com/errata/RHSA-2026:66561"},{"url":"https://access.redhat.com/errata/RHSA-2026:57194"}],"tags":["osv","go","csaf","vex","red-hat"],"epss":0.00179,"epssPercentile":0.07426,"cvssSource":"vendor","cwe":["CWE-59"],"ingestedAt":"2026-08-26T19:27:02.357Z","slug":"CVE-2026-39819","body":"## Overview\n\nThe \"go bug\" command writes to two files with predictable names in the system temporary directory (for example, \"/tmp\").\n\nAn attacker with access to the temporary directory can create a symlink in one of these names, causing \"go bug\" to overwrite the target of the symlink.\n\n## Affected packages\n\n- `toolchain >= 1.26.0-0, < 1.26.3`\n\n## Remediation\n\nUpgrade to a patched release:\n\n- `toolchain 1.26.3`\n\n## Vendor advisories\n\n- **RHSA-2026:49702** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream EUS (v. 10.0) · released 2026-08-03 · [advisory](https://access.redhat.com/errata/RHSA-2026:49702)\n- **RHSA-2026:22120** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream (v. 10) · released 2026-06-01 · [advisory](https://access.redhat.com/errata/RHSA-2026:22120)\n- **RHSA-2026:22112** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream (v. 8) · released 2026-06-01 · [advisory](https://access.redhat.com/errata/RHSA-2026:22112)\n- **RHSA-2026:61253** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream E4S (v.9.2) · released 2026-08-31 · [advisory](https://access.redhat.com/errata/RHSA-2026:61253)\n- **RHSA-2026:57649** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream E4S (v.9.4) · released 2026-08-20 · [advisory](https://access.redhat.com/errata/RHSA-2026:57649)\n- **RHSA-2026:49712** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream EUS (v.9.6) · released 2026-08-03 · [advisory](https://access.redhat.com/errata/RHSA-2026:49712)\n- **RHSA-2026:22121** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream (v. 9) · released 2026-06-01 · [advisory](https://access.redhat.com/errata/RHSA-2026:22121)\n- **RHSA-2026:62391** · Red Hat · fixed in: Red Hat Hardened Images · released 2026-09-02 · [advisory](https://access.redhat.com/errata/RHSA-2026:62391)\n- **RHSA-2026:66561** · Red Hat · fixed in: Red Hat Hardened Images · released 2026-09-11 · [advisory](https://access.redhat.com/errata/RHSA-2026:66561)\n- **RHSA-2026:57194** · Red Hat · fixed in: multicluster engine for Kubernetes 2.11 · released 2026-08-19 · [advisory](https://access.redhat.com/errata/RHSA-2026:57194)\n- **Red Hat VEX** · Moderate · affected: Red Hat Hardened Images, Multicluster Engine for Kubernetes, OpenShift API for Data Protection, Red Hat Advanced Cluster Management for Kubernetes 2, Red Hat OpenShift Container Platform 4 · no fix planned: Red Hat Hardened Images · updated 2026-09-21 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-39819.json)","depth":"sunlit","depthScore":24,"depthScoreParts":{"impact":24.2,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[{"seq":5148,"id":"CVE-2026-39819","ts":1788887250893,"field":"cvss","old":null,"new":"4.4"},{"seq":5147,"id":"CVE-2026-39819","ts":1788887250893,"field":"severity","old":"none","new":"medium"},{"seq":4031,"id":"CVE-2026-39819","ts":1788886366800,"field":"cvss","old":"4.4","new":null},{"seq":4030,"id":"CVE-2026-39819","ts":1788886366800,"field":"severity","old":"medium","new":"none"},{"seq":3159,"id":"CVE-2026-39819","ts":1788883133132,"field":"cvss","old":null,"new":"4.4"},{"seq":3158,"id":"CVE-2026-39819","ts":1788883133132,"field":"severity","old":"none","new":"medium"}]}