{"id":"CVE-2026-61626","aliases":[],"cve":{"records":[{"id":"CVE-2026-61626","source":"GitHub_M","state":"PUBLISHED","reasons":[],"replacements":[],"disputed":false,"unsupportedWhenAssigned":false,"reserved":"2026-07-10T17:38:57.110Z","published":"2026-10-30T14:52:21.006Z","modified":"2026-10-30T14:52:21.006Z"}],"publishers":[{"name":"GitHub_M","role":"CNA","organizationId":"a0819718-46f1-4df5-94e2-005712e83aaa","modified":"2026-10-30T14:52:21.006Z"}],"references":[{"url":"https://github.com/libass/libass/security/advisories/GHSA-5gf7-wjfm-vmvm","tags":["x_refsource_CONFIRM"],"source":"GitHub_M"},{"url":"https://github.com/libass/libass/commit/23da65a130bb8c5b2cf0c7df0dd7d424607f98f1","tags":["x_refsource_MISC"],"source":"GitHub_M"},{"url":"https://github.com/libass/libass/releases/tag/0.17.5","tags":["x_refsource_MISC"],"source":"GitHub_M"}],"weaknesses":[{"id":"CWE-787","description":"CWE-787: Out-of-bounds Write","source":"GitHub_M"}],"applicability":[],"prioritization":[]},"title":"libass: Out-of-bounds bit clears for negative Matroska ReadOrder values","titleSource":"GitHub_M","descriptionSource":"GitHub_M","description":"libass is a portable subtitle renderer for the ASS/SSA (Advanced Substation Alpha/Substation Alpha) subtitle format. From 0.17.4 until 0.17.5, libass event pruning does not guard negative Matroska `ReadOrder` values, allowing an attacker to clear arbitrarily many bits to zero at attacker-controlled positions near the NULL pointer. Exploitation requires a malicious Matroska stream loaded through `ass_process_chunk`, enabled read-order checking, and later pruning of the malicious events. Read-order checking is enabled by default unless `ass_set_check_readorder` is called with zero; pruning must occur explicitly through `ass_prune_events` or through automatic pruning previously enabled with `ass_configure_prune`. On common systems with arithmetic right shift, 32-bit int values, the upper address region reserved to the kernel, and matching binary/kernel architecture, the expected consequence is denial of service. More extensive exploitation on uncommon systems is theoretical and strongly constrained by the target addresses, bit-clearing-only mutation, and ASLR. This issue is fixed in version 0.17.5.","score":7.3,"severity":"high","published":"2026-10-30T14:52:21.006Z","modified":"2026-10-30T14:52:21.006Z","withdrawn":false,"knownExploited":false,"affected":[],"products":[{"vendor":"libass","name":"libass","platforms":[],"versions":[{"version":">= 0.17.4, < 0.17.5","status":"affected"}],"cpes":[],"source":"GitHub_M","url":"https://www.cve.org/CVERecord?id=CVE-2026-61626"}],"remediation":[],"references":["https://github.com/libass/libass/security/advisories/GHSA-5gf7-wjfm-vmvm","https://github.com/libass/libass/commit/23da65a130bb8c5b2cf0c7df0dd7d424607f98f1","https://github.com/libass/libass/releases/tag/0.17.5"],"sources":[{"name":"CVE","id":"CVE-2026-61626","modified":"2026-10-30T14:52:21.006Z","url":"https://www.cve.org/CVERecord?id=CVE-2026-61626"}],"assessments":[{"source":"GitHub_M","vector":"CVSS:4.0/AV:L/AC:H/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N","score":7.3}],"sourceAffected":[],"observedAt":"2026-10-30T16:30:59.296Z","kev":{"status":"not-listed","checkedAt":"2026-10-31T14:00:31.626Z"},"coverage":[{"source":"NVD","status":"not-checked"},{"source":"GHSA","status":"not-checked"},{"source":"EUVD","status":"not-checked"},{"source":"EPSS","status":"not-checked"}],"evidence":[],"aiSummary":{"text":"libass versions 0.17.4 to 0.17.5 have an out-of-bounds weakness, allowing bit clears near the NULL pointer with a malicious Matroska stream and enabled read-order checking. Exploitation requires attacker-controlled positions and pruning of malicious events. The expected consequence is denial of service.","model":"@cf/meta/llama-3.3-70b-instruct-fp8-fast","generatedAt":"2026-10-31T13:51:11.509Z","sources":[{"name":"CVE","url":"https://www.cve.org/CVERecord?id=CVE-2026-61626"}]}}