{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-121996","assignerOrgId":"53f830b8-0a3f-465b-8143-3b8a9948e749","state":"PUBLISHED","assignerShortName":"redhat","dateReserved":"2026-11-04T13:28:12.839Z","datePublished":"2026-11-05T16:08:52.127Z","dateUpdated":"2026-11-06T19:55:34.343Z"},"containers":{"cna":{"title":"Gdb: gdbserver: heap disclosure and wild pointer in gdb_parse_agent_expr via untrusted agent-expression length","metrics":[{"other":{"content":{"value":"Important","namespace":"https://access.redhat.com/security/updates/classification/"},"type":"Red Hat severity rating"}},{"cvssV3_1":{"attackComplexity":"LOW","attackVector":"NETWORK","availabilityImpact":"HIGH","baseScore":8.2,"baseSeverity":"HIGH","confidentialityImpact":"LOW","integrityImpact":"NONE","privilegesRequired":"NONE","scope":"UNCHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H","version":"3.1"},"format":"CVSS"}],"descriptions":[{"lang":"en","value":"A length validation flaw in gdbserver's agent-expression parser allows an unauthenticated remote attacker to read uninitialized heap memory from the gdbserver process and cause a denial of service. Disclosed heap content includes addresses suitable for defeating ASLR in further exploitation."}],"affected":[{"vendor":"Red Hat","product":"Red Hat Enterprise Linux 10","collectionURL":"https://access.redhat.com/downloads/content/package-browser/","packageName":"crash","defaultStatus":"unaffected","cpes":["cpe:/a:redhat:enterprise_linux:10"]},{"vendor":"Red Hat","product":"Red Hat Enterprise Linux 10","collectionURL":"https://access.redhat.com/downloads/content/package-browser/","packageName":"gdb","defaultStatus":"affected","cpes":["cpe:/a:redhat:enterprise_linux:10"]},{"vendor":"Red Hat","product":"Red Hat Enterprise Linux 6","collectionURL":"https://access.redhat.com/downloads/content/package-browser/","packageName":"gdb","defaultStatus":"affected","cpes":["cpe:/o:redhat:rhel_els:6"]},{"vendor":"Red Hat","product":"Red Hat Enterprise Linux 7","collectionURL":"https://access.redhat.com/downloads/content/package-browser/","packageName":"gdb","defaultStatus":"affected","cpes":["cpe:/o:redhat:rhel_els:7"]},{"vendor":"Red Hat","product":"Red Hat Enterprise Linux 8","collectionURL":"https://access.redhat.com/downloads/content/package-browser/","packageName":"crash","defaultStatus":"unaffected","cpes":["cpe:/a:redhat:enterprise_linux:8"]},{"vendor":"Red Hat","product":"Red Hat Enterprise Linux 8","collectionURL":"https://access.redhat.com/downloads/content/package-browser/","packageName":"gcc-toolset-14-gdb","defaultStatus":"affected","cpes":["cpe:/a:redhat:enterprise_linux:8"]},{"vendor":"Red Hat","product":"Red Hat Enterprise Linux 8","collectionURL":"https://access.redhat.com/downloads/content/package-browser/","packageName":"gcc-toolset-15-gdb","defaultStatus":"affected","cpes":["cpe:/a:redhat:enterprise_linux:8"]},{"vendor":"Red Hat","product":"Red Hat Enterprise Linux 8","collectionURL":"https://access.redhat.com/downloads/content/package-browser/","packageName":"gdb","defaultStatus":"affected","cpes":["cpe:/a:redhat:enterprise_linux:8"]},{"vendor":"Red Hat","product":"Red Hat Enterprise Linux 9","collectionURL":"https://access.redhat.com/downloads/content/package-browser/","packageName":"crash","defaultStatus":"unaffected","cpes":["cpe:/a:redhat:enterprise_linux:9"]},{"vendor":"Red Hat","product":"Red Hat Enterprise Linux 9","collectionURL":"https://access.redhat.com/downloads/content/package-browser/","packageName":"gdb","defaultStatus":"affected","cpes":["cpe:/a:redhat:enterprise_linux:9"]},{"vendor":"Red Hat","product":"Red Hat Hardened Images","collectionURL":"https://access.redhat.com/downloads/content/package-browser/","packageName":"gdb","defaultStatus":"affected","cpes":["cpe:/a:redhat:hummingbird:1"]}],"references":[{"url":"https://access.redhat.com/security/cve/CVE-2026-121996","tags":["vdb-entry","x_refsource_REDHAT"]},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2565678","name":"RHBZ#2565678","tags":["issue-tracking","x_refsource_REDHAT"]}],"datePublic":"2026-11-05T14:29:20.355Z","problemTypes":[{"descriptions":[{"cweId":"CWE-822","description":"Untrusted Pointer Dereference","lang":"en","type":"CWE"}]}],"x_redhatCweChain":"CWE-822: Untrusted Pointer Dereference","workarounds":[{"lang":"en","value":"There is no mitigation for this vulnerability. gdbserver has no authentication mechanism; exposure is limited only by network access to the gdbserver port.\n\n--- CME Mitigation Guidance (2026-11-06) ---\nDisclaimer: The following mitigation solutions are provided as a courtesy, pending the application of an official patch. This content was generated utilizing AI tools in conjunction with data from https://cmetaxonomy.org. Customers are advised to independently evaluate and test these temporary mitigations within their own infrastructure.\n\nThe highest-value action is to restrict network access to exposed gdbserver listening ports and eliminate untrusted agent-expression length handling in gdbserver: upgrade to the corresponding fixed Red Hat builds, which apply the documented input check, closing crafted agent-expression packet with declared length exceeding actual payload data. Until patched, this is a concern on Linux systems hosting gdbserver with an exposed listening port, so Restrict network access to the gdbserver listening port using host or network firewalls, limiting connectivity to trusted debugging clients only. As a compensating measure, Maintain SELinux in enforcing mode to confine the gdbserver process domain and limit host impact if heap disclosures are used to stage subsequent code execution. These controls limit blast radius and contain exploitation, but they do not fix the underlying length validation defect — apply the upstream patch to fully remediate.\n\nHighest-impact CME: CME-301 SELinux (Enforcing Mode) (medium)"}],"timeline":[{"lang":"en","time":"2026-10-21T08:41:10.000Z","value":"Reported to Red Hat."},{"lang":"en","time":"2026-11-05T14:29:20.355Z","value":"Made public."}],"credits":[{"lang":"en","value":"Red Hat would like to thank Pulkit Singh Singaria for reporting this issue."}],"providerMetadata":{"orgId":"53f830b8-0a3f-465b-8143-3b8a9948e749","shortName":"redhat","dateUpdated":"2026-11-06T19:55:34.343Z"},"x_generator":{"engine":"cvelib 1.8.0"}},"adp":[{"metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-11-05T18:52:10.802560Z","id":"CVE-2026-121996","options":[{"Exploitation":"none"},{"Automatable":"yes"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"title":"CISA ADP Vulnrichment","providerMetadata":{"orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","shortName":"CISA-ADP","dateUpdated":"2026-11-05T18:52:23.924Z"}}]}}