Inefficient Regular Expression Complexity (CWE-1333) in Elasticsearch can lead to denial of service via Regular Expression Exponential Blowup (CAPEC-492). The ES|QL CHUNK function's recursive chunking strategy accepts a list of user-supplied regular expressions used as text-splitting separators, without validating their computational complexity or bounding their execution time. An authenticated user with read access to any text-based index can submit a specially crafted regular expression that triggers catastrophic backtracking, consuming excessive CPU on Elasticsearch worker threads and degrading query throughput for other tenants on the affected node. The cluster does not crash as a result of this issue.
{
"cna_assigner": "elastic",
"cwe_ids": [
"CWE-1333"
],
"osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/102xxx/CVE-2026-102408.json",
"unresolved_ranges": [
{
"extracted_events": [
{
"range": [
{
"introduced": "8.19.0"
},
{
"last_affected": "8.19.21"
},
{
"introduced": "9.1.0"
},
{
"last_affected": "9.3.8"
},
{
"introduced": "9.4.0"
},
{
"last_affected": "9.4.7"
},
{
"introduced": "9.5.0"
},
{
"last_affected": "9.5.4"
}
],
"source": "AFFECTED_FIELD",
"strategy": "StandardRange"
}
]
}
]
}{
"extracted_events": [
{
"cpe": "cpe:2.3:a:elastic:elasticsearch:*:*:*:*:*:*:*:*",
"range": [
{
"introduced": "8.19.0"
},
{
"fixed": "8.19.22"
}
],
"source": "CPE_RANGE"
},
{
"cpe": "cpe:2.3:a:elastic:elasticsearch:*:*:*:*:*:*:*:*",
"range": [
{
"introduced": "9.1.0"
},
{
"fixed": "9.4.8"
}
],
"source": "CPE_RANGE"
},
{
"cpe": "cpe:2.3:a:elastic:elasticsearch:*:*:*:*:*:*:*:*",
"range": [
{
"introduced": "9.5.0"
},
{
"fixed": "9.5.5"
}
],
"source": "CPE_RANGE"
}
]
}
"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-102408.json"
[
{
"deprecated": false,
"digest": {
"line_hashes": [
"196795326833912774001160856107963653990",
"38118015694161648612726926093733984960",
"244889608847896122430447055695918303345",
"257344421705922307385881243254891741182",
"137363185453583447603574814007296199056",
"293305666452695760163829550541004355849",
"197353426610396809599568304775146892166",
"144755885865340705515879378218993276926",
"53917711841626796700495571597708014933",
"167396584241779245902981123042493582178"
],
"threshold": 0.9
},
"id": "CVE-2026-102408-8a40a35f",
"signature_type": "Line",
"signature_version": "v1",
"source": "https://github.com/elastic/elasticsearch/commit/3b2a41103de35e0af4064d647974032fcc1bcde9",
"target": {
"file": "x-pack/plugin/security/src/test/java/org/elasticsearch/xpack/security/authc/RoleMappingMetadataTests.java"
}
},
{
"deprecated": false,
"digest": {
"line_hashes": [
"90954522904478845627767809963626966632",
"312202333282412865980452074165561988045",
"201502984854532540743675824692178650491",
"133021856339520246587832744823698128960",
"118567998432359533306447586005283286049",
"321063442713962830327798090638255728923",
"116674126915488887653231158661015327407",
"340129969494685833618437681997224425313",
"135673196400076405753847860598907169645",
"122311869659862480733078545751265298438",
"252396072946849092724372221039036583896",
"135357956602451340512845621008925333259",
"91393826567900247708322597243985039115",
"257536988596658647353060035863545299747",
"635876167132524114432519423301563958",
"211976191649846492472867523364748761608",
"301472925400710851361978247629893735954",
"178249879224873702898662621420154824388",
"203141962289939396495271583042215390544"
],
"threshold": 0.9
},
"id": "CVE-2026-102408-903e63cd",
"signature_type": "Line",
"signature_version": "v1",
"source": "https://github.com/elastic/elasticsearch/commit/48acba663b09e70b115dd879329141506c377890",
"target": {
"file": "server/src/internalClusterTest/java/org/elasticsearch/index/shard/IndexShardIT.java"
}
},
{
"deprecated": false,
"digest": {
"function_hash": "139800561303427826632305893219156980695",
"length": 797
},
"id": "CVE-2026-102408-9f3d66c3",
"signature_type": "Function",
"signature_version": "v1",
"source": "https://github.com/elastic/elasticsearch/commit/48acba663b09e70b115dd879329141506c377890",
"target": {
"file": "server/src/internalClusterTest/java/org/elasticsearch/index/shard/IndexShardIT.java",
"function": "testNodeWriteLoadsArePresent"
}
},
{
"deprecated": false,
"digest": {
"line_hashes": [
"310522140138316022518419935707739395028",
"220506359429938391470231622354596337924",
"219515872514158714194530369631554513551",
"72875614186927229648598956343240896653",
"24931804176326139699093856965312916942",
"278658042864375250898856391712600044029",
"292645850425456433315693329416219707811",
"19099310233446518390734610261039242273"
],
"threshold": 0.9
},
"id": "CVE-2026-102408-a012b938",
"signature_type": "Line",
"signature_version": "v1",
"source": "https://github.com/elastic/elasticsearch/commit/3b2a41103de35e0af4064d647974032fcc1bcde9",
"target": {
"file": "x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/security/authz/RoleMappingMetadata.java"
}
},
{
"deprecated": false,
"digest": {
"line_hashes": [
"90954522904478845627767809963626966632",
"312202333282412865980452074165561988045",
"201502984854532540743675824692178650491",
"133021856339520246587832744823698128960",
"118567998432359533306447586005283286049",
"321063442713962830327798090638255728923",
"116674126915488887653231158661015327407",
"340129969494685833618437681997224425313",
"135673196400076405753847860598907169645",
"122311869659862480733078545751265298438",
"252396072946849092724372221039036583896",
"135357956602451340512845621008925333259",
"91393826567900247708322597243985039115",
"257536988596658647353060035863545299747",
"635876167132524114432519423301563958",
"211976191649846492472867523364748761608",
"301472925400710851361978247629893735954",
"178249879224873702898662621420154824388",
"203141962289939396495271583042215390544"
],
"threshold": 0.9
},
"id": "CVE-2026-102408-a1e3c91c",
"signature_type": "Line",
"signature_version": "v1",
"source": "https://github.com/elastic/elasticsearch/commit/c042abbb0eaaaa61b49beef21d517468861a4db2",
"target": {
"file": "server/src/internalClusterTest/java/org/elasticsearch/index/shard/IndexShardIT.java"
}
},
{
"deprecated": false,
"digest": {
"function_hash": "139800561303427826632305893219156980695",
"length": 797
},
"id": "CVE-2026-102408-a4a25bad",
"signature_type": "Function",
"signature_version": "v1",
"source": "https://github.com/elastic/elasticsearch/commit/c042abbb0eaaaa61b49beef21d517468861a4db2",
"target": {
"file": "server/src/internalClusterTest/java/org/elasticsearch/index/shard/IndexShardIT.java",
"function": "testNodeWriteLoadsArePresent"
}
},
{
"deprecated": false,
"digest": {
"function_hash": "330719214728980570805379930566702990837",
"length": 44
},
"id": "CVE-2026-102408-bde9c9dd",
"signature_type": "Function",
"signature_version": "v1",
"source": "https://github.com/elastic/elasticsearch/commit/3b2a41103de35e0af4064d647974032fcc1bcde9",
"target": {
"file": "x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/security/authz/RoleMappingMetadata.java",
"function": "context"
}
}
]
"2026-10-16T10:05:35Z"