CVE-2026-83614

xmldom: Quadratic-time parsing via the malformed-input recovery path — `parseElementStartPart` re-scan and `normalize()` adjacent-text merge

xmldom is a pure JavaScript W3C standard-based (XML DOM Level 2 Core) DOMParser and XMLSerializer module. Prior to @xmldom/xmldom versions 0.8.15 and 0.9.12, and in xmldom versions 0.3.0 through 0.6.0, two independent quadratic paths can cause denial of service. In lib/sax.js, parseElementStartPart repeatedly rescans a malformed tag name to the next > during single-character recovery; in lib/dom.js, normalize() repeatedly removes and appends adjacent text nodes, causing quadratic reindexing and string rebuilding. The first path is reachable through default DOMParser.parseFromString() processing, while the second is also reachable through a direct normalize() call on a programmatically constructed DOM, and endDocument invokes that normalization after parsing. This issue is fixed in @xmldom/xmldom versions 0.8.15 and 0.9.12; no fixed version is available for xmldom.

CVSS 4.0 · 8.7 High EPSS < 1% KEV · Not listed

Vendors

Xmldom

Products

Xmldom

CVE-2026-84305

sqlparse: Reindentation of tuple lists causes near-cap quadratic CPU consumption

sqlparse is a non-validating SQL parser module for Python. Prior to 0.6.0, sqlparse.format(sql, reindent=True) and sqlformat --reindent route attacker-controlled parenthesized tuple lists through ReindentFilter._get_offset() in sqlparse/filters/reindent.py, where _flatten_up_to_token() repeatedly rebuilds and joins the statement prefix. Thousands of offset calculations walk an expanding token tree, producing quadratic CPU consumption for inputs that remain below MAX_GROUPING_TOKENS and causing request delays, reduced throughput, or worker starvation. This issue is fixed in version 0.6.0.

CVSS 4.0 · 5.1 Medium EPSS < 1% KEV · Not listed

Vendors

Andialbrecht

Products

Sqlparse

CVE-2026-72685

Inefficient Algorithmic Complexity in Elasticsearch Leading to Denial of Service

A flaw in Elasticsearch allows a low-privileged authenticated user who can index documents to submit a single small document containing a crafted user-supplied input. Processing one such document occupies a worker thread from a bounded pool for a disproportionate amount of time, degrading the availability of indexing operations on the affected node.

CVSS 3.1 · 4.3 Medium EPSS < 1% KEV · Not listed

Vendors

Elastic

Products

Elasticsearch

CVE-2026-81722

nltk PorterStemmer before 3.10.3 Quadratic-time DoS

nltk PorterStemmer in versions <= 3.10.2 (fixed in 3.10.3) contains an inefficient-algorithmic-complexity denial of service in PorterStemmer.stem(). The _is_consonant() helper walks backward over the entire run of trailing 'y' characters on every call, and _measure() invokes it for each stem position, causing O(n^2) behavior. A single ~20-50 KB untrusted token consisting of a long run of the letter 'y' followed by a matching suffix (e.g., 'ness') can pin a CPU core for seconds to minutes, causing availability impact.

CVSS 4.0 · 8.7 High EPSS < 1% KEV · Not listed

Vendors

Nltk

Products

Nltk

CVE-2026-77831

Algorithmic-complexity denial of service in AshPaperTrail full-diff list tracking

Inefficient Algorithmic Complexity vulnerability in ash-project ash_paper_trail allows a user who can submit a large array attribute to a paper-trailed create or update action to cause a denial of service through excessive CPU and memory use. With full-diff change tracking, AshPaperTrail.ChangeBuilders.FullDiff.ListChange pairs each prior array element against the new list by rebuilding the remaining-elements accumulator with acc ++ [tuple] on every step, copying the growing list each time, so the pairing scales cubically in the array length. Nothing bounds the length and the value comes straight from action input, so one request carrying a large accepted {:array, _} attribute forces tens of seconds of CPU and multi-gigabyte allocations. This issue affects ash_paper_trail: from 0.1.1 before 0.7.0.

CVSS 4.0 · 2.1 Low EPSS < 1% KEV · Not listed

Vendors

Ash-project

Products

Ash Paper Trail

CVE-2026-75005

Apache APISIX: Unauthenticated CPU-exhaustion DoS

Inefficient Algorithmic Complexity vulnerability in Apache APISIX. A single small request can pin a gateway worker at 100% CPU for an extended period in graphql-limit-count routes. This issue affects Apache APISIX: 3.17.0. Users are recommended to upgrade to version 3.18.0, which fixes the issue.

CVSS 4.0 · 8.7 High EPSS < 1% KEV · Not listed

Vendors

Apache

Products

Apisix

CVE-2026-55099

icalendar: Algorithmic Complexity in Equality

icalendar is an RFC 5545 compatible parser and generator of iCalendar files for Python. From 7.1.0 until 7.1.3, the Component equality method in src/icalendar/cal/component.py compares nested subcomponents with two membership loops, and each membership test invokes the same method on child components, causing O(2^n) work relative to nesting depth. Component.from_ical accepts arbitrarily nested BEGIN:VEVENT blocks without a depth limit, so an attacker can submit a sub-kilobyte .ics file containing equal nested subtrees and trigger the cost when an application performs equality, inequality, membership, deduplication, test-assertion, round-trip, or normalization comparisons. Parsing alone does not trigger the issue, and comparisons that differ early short-circuit, but a few hundred bytes can pin a CPU core for minutes or indefinitely, causing denial of service in calendar sync or import endpoints, invite processing, and other comparison paths. This issue is fixed in version 7.1.3.

CVSS 3.1 · 7.5 High EPSS < 1% KEV · Not listed

Vendors

Collective

Products

Icalendar

CVE-2026-49851

Mistune: Potential DoS via quadratic-time parsing in parse_link_text

Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.3.0, Mistune is vulnerable to a CPU exhaustion DoS due to superlinear (approximately O(n²)) behavior in parse_link_text. When parsing Markdown containing many consecutive [ characters, parse_link_text repeatedly scans the input using a regex search inside a loop. Each iteration re-scans a large portion of the remaining string, resulting in quadratic-time behavior. An attacker-controlled Markdown input can therefore trigger excessive CPU usage with a very small payload. This vulnerability is fixed in 3.3.0.

CVSS 4.0 · 8.7 High EPSS < 1% KEV · Not listed

Vendors

Lepture

Products

Mistune

CVE-2026-58436

ParseAcceptLanguage quadratic-time DoS via Locale middleware on unauthenticated requests

ParseAcceptLanguage quadratic-time DoS via Locale middleware on unauthenticated requests

CVSS 3.1 · 7.5 High EPSS < 1% KEV · Not listed

Vendors

Gitea

Products

Gitea Open Source Git Server

CVE-2026-59887

linkify-it: Quadratic-complexity DoS via the `mailto:` validator scan-loop on attacker text

linkify-it is a links recognition library with full Unicode support. Prior to 5.0.2, the mailto: schema validator used by .test() and .match() can be invoked at every mailto: occurrence and scan the remaining input through src_email_name in lib/re.mjs, causing O(n^2) CPU consumption on crafted user text. This issue is fixed in version 5.0.2.

CVSS 3.1 · 7.5 High EPSS < 1% KEV · Not listed

Vendors

Markdown-it

Products

Linkify-it

CVE-2026-76401

Regular Expression Denial of Service (DoS) through the REST API in Splunk Connect for Kafka

In Splunk Connect for Kafka versions below 2.2.7, an unauthenticated user who can reach the Kafka Connect Representational State Transfer (REST) API could configure timestamp extraction with a crafted regular expression and matching event data to block a Kafka Connect worker thread, stopping event delivery for the affected connector. The vulnerability is possible because timestamp extraction evaluates customer-supplied regular expressions without a time limit. For more information see Install Splunk Connect for Kafka (https://help.splunk.com/en/data-management/integrate-data-with-add-ons/splunk-connect-for-kafka/2.2/install/install-splunk-connect-for-kafka) and Data ingestion parameters for Splunk Connect for Kafka (https://help.splunk.com/en/data-management/integrate-data-with-add-ons/splunk-connect-for-kafka/2.2/overview/data-ingestion-parameters-for-splunk-connect-for-kafka) in the Splunk documentation.

CVSS 3.1 · 5.9 Medium EPSS < 1% KEV · Not listed

Vendors

Splunk

Products

Connect For Kafka Splunk Connect For Kafka

CVE-2026-71491

sqlparse: Quadratic O(n²) DoS in group_comments

sqlparse is a non-validating SQL parser module for Python. Prior to 0.6.0, group_comments in sqlparse/engine/grouping.py repeatedly rescans comment-only statements before the MAX_GROUPING_TOKENS guard, causing quadratic CPU consumption through sqlparse.parse() and sqlparse.format(sql, strip_comments=True). This issue is fixed in version 0.6.0.

CVSS 4.0 · 8.7 High EPSS < 1% KEV · Not listed

Vendors

Andialbrecht

Products

Sqlparse

CVE-2026-54284

sqlparse: TokenList.__init__ materializes O(subtree) value per group, causing CPU DoS before depth/token caps trigger

sqlparse is a non-validating SQL parser module for Python. Prior to 0.6.0, TokenList construction and string conversion in sqlparse/sql.py repeatedly flatten nested token subtrees constructed by group_parenthesis and group_case, causing quadratic CPU consumption through sqlparse.parse(), sqlparse.format(), and sqlparse.split() before depth and token limits terminate processing. This issue is fixed in version 0.6.0.

CVSS 4.0 · 8.7 High EPSS < 1% KEV · Not listed

Vendors

Andialbrecht

Products

Sqlparse

CVE-2026-68750

Quadratic sibling re-flattening in the html_sanitize_ex traversal engine allows CPU-exhaustion denial of service

Inefficient Algorithmic Complexity vulnerability in the traversal engine in rrrene html_sanitize_ex allows an unauthenticated remote attacker to exhaust server CPU and memory via a flat run of sibling elements in sanitized HTML. The list clause of HtmlSanitizeEx.Traverser.traverse/2 recurses on the tail of a sibling list and then evaluates List.flatten([head] ++ tail) over the already flattened result, so every one of n siblings copies and re-walks the entire remaining tail. The flattening is only needed for the rare case where scrub returns several replacement nodes for one node, but the cost is paid across the whole tail at every step, making traversal quadratic in sibling count. The traverser sits on every public entry point, so no particular scrubber or configuration is required and the payload needs only allowed tags. A 160 KB body of 20,000 sibling elements occupies a scheduler for roughly 1.7 seconds, and the cost grows faster than the body does. This issue affects html_sanitize_ex: from 0.3.1 before 1.4.5 and from 1.5.0-rc.0 before 1.5.3.

CVSS 4.0 · 8.2 High EPSS < 1% KEV · Not listed

Vendors

Rrrene

Products

Html Sanitize Ex Htmlsanitizeex

CVE-2026-41292

Long list of incoming EDNS options degrades performance

NLnet Labs Unbound up to and including version 1.25.0 is vulnerable to a degradation of service attack related to parsing long lists of incoming EDNS options. An adversary sending queries with too many EDNS options can hold Unbound threads hostage while they are parsing and creating internal data structures for the options. Coordinated attacks can result in degradation and/or denial of service. Unbound 1.25.1 contains a patch with a fix to limit acceptable incoming EDNS options (100).

CVSS 4.0 · 6.6 Medium EPSS < 1% KEV · Not listed

Vendors

Nlnetlabs

Products

Unbound

CVE-2026-56860

Avoid quadratic complexity in resolvePath in net/url

Previously, resolving relative paths containing parent directory ('..') segments performed string conversions and buffer rewrites on each step, resulting in quadratic time complexity and high memory allocation overhead. Now, path resolution operates on a byte buffer using index-based backtracking for '..' segments, eliminating the quadratic time complexity and significantly reducing memory allocations.

CVSS 3.1 · 5.9 Medium EPSS < 1% KEV · Not listed

Vendors

Go Standard Library

Products

Net/url

CVE-2026-70453

rsync < 3.5.0 Algorithmic Complexity DoS via hash_search()

rsync before 3.5.0 contains an algorithmic complexity vulnerability in the hash_search() function that allows a remote attacker to cause a denial of service by delivering a carefully constructed file list. A sender can exploit the quadratic-time worst-case behavior in hash lookups to exhaust receiver CPU resources with a modest number of crafted entries, causing a sustained denial of service.

CVSS 4.0 · 8.7 High EPSS < 1% KEV · Not listed

Vendors

Rsync Project Samba

Products

Rsync Rsync

CVE-2026-73413

Shescape: Quadratic-time denial of service in flag-protection

Shescape is a simple shell escape library for JavaScript. From 2.1.11 until 2.1.14 and 3.0.1, the flag-protection loop in compose in src/internal/compose.js repeatedly joins and slices flag fragments when flagProtection is enabled, which is the default, making processing quadratic in input size across the escape, escapeAll, quote, and quoteAll APIs. An attacker who can supply a large untrusted input containing many flag fragments can consume CPU and cause denial of service. This issue is fixed in versions 2.1.14 and 3.0.1.

CVSS 4.0 · 8.7 High EPSS < 1% KEV · Not listed

Vendors

Ericcornelissen

Products

Shescape

CVE-2026-6879

Quadratic Behavior in xml.etree.ElementPath Index Predicates

`Element.findall()` and fully-consumed `Element.iterfind()` exhibit `O(n^2)` time complexity when using XPath index predicates (e.g. `[1]`, `[last()]`, `[last()-N]`) on XML documents with many same-tag siblings. `Element.find()` is only affected when the first match is near the end  of the sibling list, such as with `[last()]` or `[last()-N]`;  `.//item[1]` short-circuits after the first match.

CVSS 4.0 · 2 Low EPSS < 1% KEV · Not listed

Vendors

Python Redhat

Products

Cpython Hummingbird

CVE-2026-71848

Hono: Algorithmic Complexity DoS in Language Middleware

Hono is a Web application framework that provides support for any JavaScript runtime. From 4.12.0 to 4.12.33, the languageDetector middleware is vulnerable to algorithmic complexity denial of service when processing a crafted language tag containing a large number of hyphen separated subtags. To implement progressive language tag truncation, normalizeLanguage() repeatedly calls parts.slice(0, i).join('-') for every possible prefix, so the total amount of string processing grows quadratically with the number of subtags. Language values may come from a query parameter, cookie, Accept-Language header, or URL path, depending on the detector configuration, and the default detector order enables query string, cookie, and header detection, so applications using languageDetector() may expose this processing to unauthenticated requests. An attacker may repeatedly send requests containing long, hyphen separated language tags, causing excessive CPU consumption and preventing unrelated requests from being processed. This issue is fixed in version 4.12.34.

CVSS 3.1 · 5.3 Medium EPSS < 1% KEV · Not listed

Vendors

Hono

Products

Hono