{"id":"CVE-2026-118593","kind":"vulnerability","aliases":["CVE-2026-118593"],"related":[],"title":"Red Hat Enterprise Linux 9 kernel: SRv6 packet drop path can stall system","description":"A flaw was found in Red Hat Enterprise Linux 9 kernel builds. An incomplete backport of the CVE-2026-46099 fix in RHEL 9.6 through 9.10 left a local_bh imbalance in seg6_input_core(), where the drop path returns with bottom halves still disabled. This can lead to softirq starvation and denial of service on systems with SRv6 tunnels configured. Upstream and RHEL 10 are not affected.","summary":"An incomplete backport of an earlier kernel fix leaves bottom halves disabled when SRv6 packets are dropped in seg6_input_core(). This can starve softirq processing and cause a denial of service on systems with SRv6 tunnels configured.","severity":"medium","cvss":5.9,"epss":null,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["infrastructure","linux-kernel","rhel","self-hosted","srv6"],"not_affected_if":["no-srv6-tunnels","rhel-10","upstream-kernel"],"how_to_check":"- Check the RHEL release with `cat /etc/redhat-release` and confirm whether it is 9.6 through 9.10.\n- Check whether SRv6 tunnels are configured on the host (the sources do not name a specific command or file).","fix":null,"status":"open","published_at":"2026-10-30T07:16:33+00:00","first_seen_at":"2026-10-30T07:29:00+00:00","triaged_at":"2026-10-30T07:30:08+00:00","updated_at":"2026-10-30T07:30:08+00:00","category":"infrastructure","confidence":0.6,"triage":{"at":"2026-10-30T07:30:08Z","model":"claude-haiku-5-5","output":{"fix":"unknown","reach":"local","title":"Red Hat Enterprise Linux 9 kernel: SRv6 packet drop path can stall system","impact":"low","summary":"An incomplete backport of an earlier kernel fix leaves bottom halves disabled when SRv6 packets are dropped in seg6_input_core(). This can starve softirq processing and cause a denial of service on systems with SRv6 tunnels configured.","audience":"businesses","category":"infrastructure","nicknames":[],"who_cares":["rhel","linux-kernel","srv6","self-hosted"],"confidence":0.6,"fix_status":"unknown","needs_auth":"unknown","worst_case":"Denial of service through softirq starvation on the affected host","analyst_note":"Confirm the fixed kernel package version for RHEL 9.6 through 9.10 and whether the trigger is remote or only local, using the Red Hat errata for CVE-2026-118593.","how_to_check":"- Check the RHEL release with `cat /etc/redhat-release` and confirm whether it is 9.6 through 9.10.\n- Check whether SRv6 tunnels are configured on the host (the sources do not name a specific command or file).","plain_action":"","needs_analyst":true,"not_affected_if":["upstream-kernel","rhel-10","no-srv6-tunnels"],"who_is_affected":"Systems running Red Hat Enterprise Linux 9.6 through 9.10 kernel builds that have SRv6 tunnels configured are exposed. Upstream kernels and RHEL 10 are not affected according to the description, so those systems can skip it.","user_interaction":"no","needs_special_setup":"yes","severity_if_unknown":"medium"},"cost_usd":0.000714,"input_tokens":4169,"output_tokens":594,"severity_before":"medium"},"analyst_status":null,"analyst_note":null,"search":"'-118593':16A,19A '-2026':15A,18A,85C '-46099':86C '10':131C '9':5A,76C '9.10':92C '9.6':90C 'affect':134C 'backport':31B,81C 'bh':96C 'bottom':38B,108C 'build':78C 'caus':56B 'configur':66B,127C 'core':49B,101C 'cve':14A,17A,84C 'denial':58B,119C 'disabl':40B,111C 'drop':9A,45B,104C 'earlier':34B 'enterpris':3A,74C 'fix':36B,87C 'flaw':68C 'found':70C 'halv':39B,109C 'hat':2A,73C 'host':27B 'imbal':97C 'incomplet':30B,80C 'infrastructur':20B 'input':48B,100C 'kernel':6A,23B,35B,77C 'lead':114C 'leav':37B 'left':93C 'linux':4A,22B,75C 'linux-kernel':21B 'local':95C 'packet':8A,43B 'path':10A,105C 'process':54B 'red':1A,72C 'return':106C 'rhel':24B,89C,130C 'seg6':47B,99C 'self':26B 'self-host':25B 'servic':60B,121C 'softirq':53B,116C 'srv6':7A,28B,42B,64B,125C 'stall':12A 'starv':52B 'starvat':117C 'still':110C 'system':13A,62B,123C 'tunnel':65B,126C 'upstream':128C","nicknames":[],"mitigations":[],"who_affected":"Systems running Red Hat Enterprise Linux 9.6 through 9.10 kernel builds that have SRv6 tunnels configured are exposed. Upstream kernels and RHEL 10 are not affected according to the description, so those systems can skip it.","tier":"C","verified":{},"analyst_revisit_at":null,"fix_status":"none","audience":"businesses","plain_action":null,"first_public_at":"2026-10-30T07:16:33+00:00","kev":null,"cvss_vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H","cvss_by":"secalert@redhat.com","poc_count":0,"sources":[{"source":"nvd","external_id":"CVE-2026-118593","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-118593","severity":null,"published_at":"2026-10-30T07:16:33+00:00","modified_at":"2026-10-30T07:16:33+00:00","first_seen_at":"2026-10-30T07:29:00+00:00","fetched_at":"2026-10-30T07:29:00+00:00","note":null}],"documents":[],"notice":"Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai"}