{"id":14993,"date":"2026-09-04T19:02:21","date_gmt":"2026-09-04T11:02:21","guid":{"rendered":"https:\/\/www.54iter.cn\/?vuln=cve-2026-63984"},"modified":"2026-09-04T19:02:21","modified_gmt":"2026-09-04T11:02:21","slug":"cve-2026-63984","status":"publish","type":"vuln","link":"https:\/\/www.54iter.cn\/?vuln=cve-2026-63984","title":{"rendered":"CVE-2026-63984 [CRITICAL] &#8211; In the Linux kernel, the following vulnerability has been resolved:\n\nipv6: rpl: fix hdrlen"},"content":{"rendered":"<p>In the Linux kernel, the following vulnerability has been resolved:<\/p>\n<p>ipv6: rpl: fix hdrlen overflow in ipv6_rpl_srh_decompress()<\/p>\n<p>ipv6_rpl_srh_decompress() computes:<\/p>\n<p>    outhdr-&gt;hdrlen = (((n + 1) * sizeof(struct in6_addr)) &gt;&gt; 3);<\/p>\n<p>hdrlen is __u8. For n &gt;= 127 the result exceeds 255 and silently<br \/>\ntruncates. With n=127 (cmpri=15, cmpre=15, pad=0, hdrlen=16):<\/p>\n<p>    (128 * 16) &gt;&gt; 3 = 256, truncated to 0 as __u8<\/p>\n<p>The caller in ipv6_rpl_srh_rcv() then places the compressed header<br \/>\nat buf + ((ohdr-&gt;hdrlen + 1) &lt; 255, which<br \/>\nprevents n+1 from overflowing unsigned char (the segments_left<br \/>\nfield), but does not prevent the computed hdrlen from overflowing<br \/>\n__u8. n=127 passes because 128  127. This caps n at 126, giving<br \/>\nhdrlen = (127 * 16) &gt;&gt; 3 = 254, which fits in __u8. The compressed<br \/>\nheader then lands at buf + ((254 + 1) &lt;&lt; 3) = buf + 2040, exactly<br \/>\npast the decompressed region (buf[0..2039]). No overlap. 127<br \/>\nsegments is well beyond any realistic RPL deployment.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>In the Linux kernel, the following vulnerability has been resolved:<\/p>\n<p>ipv6: rpl: fix hdrlen overflow in ipv6_rpl_srh_decompress()<\/p>\n<p>ipv6_rpl_srh_decompress() computes:<\/p>\n<p>    outhdr-&gt;hdrlen = (((n + 1) * <\/p>\n","protected":false},"template":"","meta":[],"categories":[],"tags":[],"class_list":["post-14993","vuln","type-vuln","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=\/wp\/v2\/vuln\/14993","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=\/wp\/v2\/vuln"}],"about":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=\/wp\/v2\/types\/vuln"}],"wp:attachment":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=14993"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=14993"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=14993"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}