{"id":81933,"date":"2026-07-13T20:46:48","date_gmt":"2026-07-13T17:16:48","guid":{"rendered":"https:\/\/afaghhosting.net\/blog\/cve-2026-13221-perl-versions-through-5-43-9-produce-silently-incorrect-regular-expression-matches-when-an-alternation-of-more-than-65535-fixed-string-branches-is-compiled-into-a-trie-in-perl_study_c\/"},"modified":"2026-07-13T20:46:48","modified_gmt":"2026-07-13T17:16:48","slug":"cve-2026-13221-perl-versions-through-5-43-9-produce-silently-incorrect-regular-expression-matches-when-an-alternation-of-more-than-65535-fixed-string-branches-is-compiled-into-a-trie-in-perl_study_c","status":"publish","type":"post","link":"https:\/\/afaghhosting.net\/blog\/cve-2026-13221-perl-versions-through-5-43-9-produce-silently-incorrect-regular-expression-matches-when-an-alternation-of-more-than-65535-fixed-string-branches-is-compiled-into-a-trie-in-perl_study_c\/","title":{"rendered":"CVE-2026-13221 &#8211; Perl versions through 5.43.9 produce silently incorrect regular expression matches when an alternation of more than 65535 fixed string branches is compiled into a trie in Perl_study_chunk"},"content":{"rendered":"<p>CVE ID :CVE-2026-13221<\/p>\n<p>  Published : July 13, 2026, 5:16 p.m. | 13\u00a0minutes ago<\/p>\n<p>  Description :Perl versions through 5.43.9 produce silently incorrect regular expression matches when an alternation of more than 65535 fixed string branches is compiled into a trie in Perl_study_chunk.<\/p>\n<p>When such branches are combined into a trie, the delta between the first branch and the shared tail is stored in a 16-bit field. A branch count above 65535 overflows the field, and the trie&#8217;s match decision table is truncated with no warning or error.<\/p>\n<p>A pattern of this shape produces false positive matches (matching strings it should not) and false negative matches (failing to match strings it should). When such a pattern gates an access or filtering decision, the result is wrong.<\/p>\n<p>  Severity: 0.0 | NA<\/p>\n<p>  Visit the link for more details, such as CVSS details, affected products, timeline, and more&#8230;\u00a0<\/p>\n","protected":false},"excerpt":{"rendered":"<p>CVE ID :CVE-2026-13221 Published : July 13, 2026, 5:16 p.m. | 13\u00a0minutes ago Description :Perl versions through 5.43.9 produce silently incorrect regular expression matches when an alternation of more than 65535 fixed string branches is compiled into a trie in Perl_study_chunk. When such branches are combined into a trie, the delta between the first branch &hellip;<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[26],"tags":[],"class_list":["post-81933","post","type-post","status-publish","format-standard","hentry","category-vulnerability"],"_links":{"self":[{"href":"https:\/\/afaghhosting.net\/blog\/wp-json\/wp\/v2\/posts\/81933","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/afaghhosting.net\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/afaghhosting.net\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/afaghhosting.net\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/afaghhosting.net\/blog\/wp-json\/wp\/v2\/comments?post=81933"}],"version-history":[{"count":0,"href":"https:\/\/afaghhosting.net\/blog\/wp-json\/wp\/v2\/posts\/81933\/revisions"}],"wp:attachment":[{"href":"https:\/\/afaghhosting.net\/blog\/wp-json\/wp\/v2\/media?parent=81933"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/afaghhosting.net\/blog\/wp-json\/wp\/v2\/categories?post=81933"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/afaghhosting.net\/blog\/wp-json\/wp\/v2\/tags?post=81933"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}