{"id":"GHSA-6xh2-93p9-vqh4","summary":"oban_web: Unbounded range expansion in cron describe causes memory exhaustion","details":"### Summary\n\n`oban_web` 2.12.0 introduced a cron expression parser that expands `-`-separated ranges without validating the endpoints. An attacker with access to schedule cron jobs can submit a malicious expression; when any user with dashboard access views the cron job list, `Oban.Web.CronExpr.describe/1` is called to render it, triggering allocation of gigabytes of memory and stalling or crashing the BEAM node.\n\n### Details\n\n**1. Scheduling:** The attacker submits a cron job with a malicious expression such as `\"0 0 1-100000000 * *\"`. No special privilege is required beyond the ability to schedule cron jobs.\n\n**2. Parsing:** When the cron list is rendered in the dashboard, `describe/1` calls `parse_range/1` in `lib/oban/web/cron_expr.ex`, which calls `Integer.parse/1` on both endpoints of the range with no bounds check, returning `{:range, start_val, end_val}` for any integers.\n\n**3. Eager expansion:** `expand_dom_parts/1` and `expand_dow_parts/1` materialise the range via `Enum.to_list(start_val..end_val)`. The input above produces ~100 million integers (~2.4 GB). A sibling helper `extract_dom_values` already validates range bounds, but the expansion helpers do not.\n\n### PoC\n\n1. Schedule a cron job with expression `\"0 0 1-100000000 * *\"` (or any expression with an out-of-domain range).\n2. Have any user with Oban.Web dashboard access navigate to the cron job list.\n3. The dashboard calls `describe/1` to render the expression, exhausting BEAM memory and crashing the node.\n\n### Impact\n\nCVSS 4.0 score 5.9 (Medium). Affects `oban_web` \u003e= 2.12.0. Requires the ability to schedule a cron job and a dashboard user to view the cron list; no further privileges are needed.\n\n### References\n\n* Introduction commit: https://github.com/oban-bg/oban_web/commit/a97c7960bb389b05aaab4cf8042985f02ceddc24\n* Patch commit: https://github.com/oban-bg/oban_web/commit/9998b7e284e02fdd4645dd6231760038e63b584d","aliases":["CVE-2026-48593","EEF-CVE-2026-48593"],"modified":"2026-06-30T18:45:32.157103330Z","published":"2026-06-30T18:32:49Z","database_specific":{"nvd_published_at":"2026-05-26T21:16:41Z","cwe_ids":["CWE-400"],"severity":"MODERATE","github_reviewed":true,"github_reviewed_at":"2026-06-30T18:32:49Z"},"references":[{"type":"WEB","url":"https://github.com/oban-bg/oban_web/security/advisories/GHSA-6xh2-93p9-vqh4"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-48593"},{"type":"WEB","url":"https://github.com/oban-bg/oban_web/commit/9998b7e284e02fdd4645dd6231760038e63b584d"},{"type":"WEB","url":"https://github.com/oban-bg/oban_web/commit/a97c7960bb389b05aaab4cf8042985f02ceddc24"},{"type":"WEB","url":"https://cna.erlef.org/cves/CVE-2026-48593.html"},{"type":"PACKAGE","url":"https://github.com/oban-bg/oban_web"},{"type":"WEB","url":"https://osv.dev/vulnerability/EEF-CVE-2026-48593"}],"affected":[{"package":{"name":"oban_web","ecosystem":"Hex","purl":"pkg:hex/oban_web"},"ranges":[{"type":"SEMVER","events":[{"introduced":"2.12.0"},{"fixed":"2.12.5"}]}],"versions":["2.12.0","2.12.1","2.12.2","2.12.3","2.12.4"],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/06/GHSA-6xh2-93p9-vqh4/GHSA-6xh2-93p9-vqh4.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V4","score":"CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N"}]}