{"schemaVersion":3,"id":"CVE-2026-77680","aliases":["UBUNTU-CVE-2026-77680","DEBIAN-CVE-2026-77680"],"status":"published","duplicateOf":null,"title":null,"description":"An algorithmic complexity flaw exists in libsoup's HTTP Range header processing that persists after the CVE-2025-32907 fix.\n\nCVE-2025-32907 addressed memory amplification when a client repeated the same range many times in a single Range header. Commit 9bb92f7a corrected merge correctness in soup_message_headers_get_ranges_internal() in libsoup/soup-message-headers.c, but the coalescing loop still removes merged ranges using g_array_remove_index() for each coalesced element. Because GArray is contiguous, each mid-array removal performs an O(N) memmove. When many identical satisfiable ranges are supplied (for example bytes=0-0 repeated thousands of times), the loop performs O(N²) work coalescing them into a single range.\n\nThe vulnerable path is reachable server-side from handle_partial_get() in libsoup/server/http1/soup-server-message-io-http1.c when a SoupServer handler returns HTTP 200 with a non-empty body. No authentication is required. The number of ranges is bounded only by the maximum request header size (~100 KiB), allowing roughly 25,000 ranges per request. Reporter measurements on libsoup HEAD containing the CVE-2025-32907 fix show ~90 ms single-core CPU per such request at the wire maximum, blocking the server's event loop for that duration.\n\nThis is a CPU exhaustion / availability issue only. No memory corruption or information disclosure occurs.\n\nAffected: libsoup versions containing the CVE-2025-32907 fix but not merge request !550.\nFixed upstream: MR !550 merged 2026-08-20, replacing per-element removal with O(N) in-place compaction and rejecting Range headers requesting more than 200 ranges.\nUpstream report: https://gitlab.gnome.org/GNOME/libsoup/-/issues/538\nRelated: CVE-2025-32907","dates":{"published":"2026-08-25T20:36:45.808Z","modified":"2026-08-26T12:43:47.896Z","reserved":null,"kevAdded":[],"kevDue":[]},"cvss":{"headline":{"score":5.3,"severity":"medium","version":"3.1","versionLabel":"v3.1","source":"CVE.org","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L","computed":false,"selection":"backend-summary"},"metrics":[{"version":"3.1","versionLabel":"v3.1","source":"CVE.org","score":5.3,"severity":"medium","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L","exploitability":null,"impact":null,"computed":false},{"version":"3.1","versionLabel":"v3.1","source":"OSV · Ubuntu","score":5.3,"severity":"medium","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L","exploitability":10,"impact":2.3,"computed":true},{"version":"3.1","versionLabel":"v3.1","source":"OSV · 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REDHAT"]},{"url":"https://access.redhat.com/security/cve/CVE-2026-77680","label":"access.redhat.com/security/cve/CVE-2026-77680","hostname":"access.redhat.com","tags":["VDB Entry","X Refsource REDHAT"]},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2520892","label":"bugzilla.redhat.com/show_bug.cgi?id=2520892","hostname":"bugzilla.redhat.com","tags":["Issue Tracking","X Refsource REDHAT"]},{"url":"https://gitlab.gnome.org/GNOME/libsoup/-/issues/538","label":"gitlab.gnome.org/GNOME/libsoup/-/issues/538","hostname":"gitlab.gnome.org","tags":["REPORT"]},{"url":"https://gitlab.gnome.org/GNOME/libsoup/-/merge_requests/550","label":"gitlab.gnome.org/GNOME/libsoup/-/merge_requests/550","hostname":"gitlab.gnome.org","tags":["REPORT"]},{"url":"https://ubuntu.com/security/CVE-2026-77680","label":"ubuntu.com/security/CVE-2026-77680","hostname":"ubuntu.com","tags":["REPORT"]},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-77680","label":"www.cve.org/CVERecord?id=CVE-2026-77680","hostname":"www.cve.org","tags":["REPORT"]},{"url":"https://ubuntu.com/security/notices/USN-8890-1","label":"ubuntu.com/security/notices/USN-8890-1","hostname":"ubuntu.com","tags":["Advisory"]},{"url":"https://security-tracker.debian.org/tracker/CVE-2026-77680","label":"security-tracker.debian.org/tracker/CVE-2026-77680","hostname":"security-tracker.debian.org","tags":["Advisory"]}],"lineage":{"upstream":[],"downstream":["OPENSUSE-SU-2026:11860-1","SUSE-SU-2026:4703-1","SUSE-SU-2026:4739-1","USN-8890-1"],"duplicates":[],"related":["OPENSUSE-SU-2026:11860-1","SUSE-SU-2026:4703-1","SUSE-SU-2026:4739-1","USN-8890-1"]},"timeline":[{"kind":"published","date":"2026-08-25T20:36:45.808Z","label":"Published","detail":"Vulnerability 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