CVE-2026-121996 (GCVE-0-2026-121996)
Vulnerability from cvelistv5 – Published: 2026-11-05 16:08 – Updated: 2026-11-06 19:55
VLAI
EPSS
VEX
Title
Gdb: gdbserver: heap disclosure and wild pointer in gdb_parse_agent_expr via untrusted agent-expression length
Summary
A length validation flaw in gdbserver's agent-expression parser allows an unauthenticated remote attacker to read uninitialized heap memory from the gdbserver process and cause a denial of service. Disclosed heap content includes addresses suitable for defeating ASLR in further exploitation.
Severity
8.2 (High)
SSVC
Exploitation: none
Automatable: yes
Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-11-05 18:52 UTC
CWE
- CWE-822 - Untrusted Pointer Dereference
Assigner
redhat
CNA
References
2 references
| URL | Tags |
|---|---|
| https://access.redhat.com/security/cve/CVE-2026-121996 | vdb-entryx_refsource_REDHAT |
| https://bugzilla.redhat.com/show_bug.cgi?id=2565678 | issue-trackingx_refsource_REDHAT |
Impacted products
6 products
| Vendor | Product | Version | |
|---|---|---|---|
| Red Hat | Red Hat Enterprise Linux 10 |
cpe:/a:redhat:enterprise_linux:10
|
|
| Red Hat | Red Hat Enterprise Linux 6 |
cpe:/o:redhat:rhel_els:6
|
|
| Red Hat | Red Hat Enterprise Linux 7 |
cpe:/o:redhat:rhel_els:7
|
|
| Red Hat | Red Hat Enterprise Linux 8 |
cpe:/a:redhat:enterprise_linux:8
|
|
| Red Hat | Red Hat Enterprise Linux 9 |
cpe:/a:redhat:enterprise_linux:9
|
|
| Red Hat | Red Hat Hardened Images |
cpe:/a:redhat:hummingbird:1
|
Date Public
2026-11-05 14:29
{
"containers": {
"adp": [
{
"metrics": [
{
"other": {
"content": {
"id": "CVE-2026-121996",
"options": [
{
"Exploitation": "none"
},
{
"Automatable": "yes"
},
{
"Technical Impact": "partial"
}
],
"role": "CISA Coordinator",
"timestamp": "2026-11-05T18:52:10.802560Z",
"version": "2.0.3"
},
"type": "ssvc"
}
}
],
"providerMetadata": {
"dateUpdated": "2026-11-05T18:52:23.924Z",
"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"shortName": "CISA-ADP"
},
"title": "CISA ADP Vulnrichment"
}
],
"cna": {
"affected": [
{
"collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
"cpes": [
"cpe:/a:redhat:enterprise_linux:10"
],
"defaultStatus": "unaffected",
"packageName": "crash",
"product": "Red Hat Enterprise Linux 10",
"vendor": "Red Hat"
},
{
"collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
"cpes": [
"cpe:/a:redhat:enterprise_linux:10"
],
"defaultStatus": "affected",
"packageName": "gdb",
"product": "Red Hat Enterprise Linux 10",
"vendor": "Red Hat"
},
{
"collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
"cpes": [
"cpe:/o:redhat:rhel_els:6"
],
"defaultStatus": "affected",
"packageName": "gdb",
"product": "Red Hat Enterprise Linux 6",
"vendor": "Red Hat"
},
{
"collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
"cpes": [
"cpe:/o:redhat:rhel_els:7"
],
"defaultStatus": "affected",
"packageName": "gdb",
"product": "Red Hat Enterprise Linux 7",
"vendor": "Red Hat"
},
{
"collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
"cpes": [
"cpe:/a:redhat:enterprise_linux:8"
],
"defaultStatus": "unaffected",
"packageName": "crash",
"product": "Red Hat Enterprise Linux 8",
"vendor": "Red Hat"
},
{
"collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
"cpes": [
"cpe:/a:redhat:enterprise_linux:8"
],
"defaultStatus": "affected",
"packageName": "gcc-toolset-14-gdb",
"product": "Red Hat Enterprise Linux 8",
"vendor": "Red Hat"
},
{
"collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
"cpes": [
"cpe:/a:redhat:enterprise_linux:8"
],
"defaultStatus": "affected",
"packageName": "gcc-toolset-15-gdb",
"product": "Red Hat Enterprise Linux 8",
"vendor": "Red Hat"
},
{
"collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
"cpes": [
"cpe:/a:redhat:enterprise_linux:8"
],
"defaultStatus": "affected",
"packageName": "gdb",
"product": "Red Hat Enterprise Linux 8",
"vendor": "Red Hat"
},
{
"collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
"cpes": [
"cpe:/a:redhat:enterprise_linux:9"
],
"defaultStatus": "unaffected",
"packageName": "crash",
"product": "Red Hat Enterprise Linux 9",
"vendor": "Red Hat"
},
{
"collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
"cpes": [
"cpe:/a:redhat:enterprise_linux:9"
],
"defaultStatus": "affected",
"packageName": "gdb",
"product": "Red Hat Enterprise Linux 9",
"vendor": "Red Hat"
},
{
"collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
"cpes": [
"cpe:/a:redhat:hummingbird:1"
],
"defaultStatus": "affected",
"packageName": "gdb",
"product": "Red Hat Hardened Images",
"vendor": "Red Hat"
}
],
"credits": [
{
"lang": "en",
"value": "Red Hat would like to thank Pulkit Singh Singaria for reporting this issue."
}
],
"datePublic": "2026-11-05T14:29:20.355Z",
"descriptions": [
{
"lang": "en",
"value": "A length validation flaw in gdbserver\u0027s agent-expression parser allows an unauthenticated remote attacker to read uninitialized heap memory from the gdbserver process and cause a denial of service. Disclosed heap content includes addresses suitable for defeating ASLR in further exploitation."
}
],
"metrics": [
{
"other": {
"content": {
"namespace": "https://access.redhat.com/security/updates/classification/",
"value": "Important"
},
"type": "Red Hat severity rating"
}
},
{
"cvssV3_1": {
"attackComplexity": "LOW",
"attackVector": "NETWORK",
"availabilityImpact": "HIGH",
"baseScore": 8.2,
"baseSeverity": "HIGH",
"confidentialityImpact": "LOW",
"integrityImpact": "NONE",
"privilegesRequired": "NONE",
"scope": "UNCHANGED",
"userInteraction": "NONE",
"vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H",
"version": "3.1"
},
"format": "CVSS"
}
],
"problemTypes": [
{
"descriptions": [
{
"cweId": "CWE-822",
"description": "Untrusted Pointer Dereference",
"lang": "en",
"type": "CWE"
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-11-06T19:55:34.343Z",
"orgId": "53f830b8-0a3f-465b-8143-3b8a9948e749",
"shortName": "redhat"
},
"references": [
{
"tags": [
"vdb-entry",
"x_refsource_REDHAT"
],
"url": "https://access.redhat.com/security/cve/CVE-2026-121996"
},
{
"name": "RHBZ#2565678",
"tags": [
"issue-tracking",
"x_refsource_REDHAT"
],
"url": "https://bugzilla.redhat.com/show_bug.cgi?id=2565678"
}
],
"timeline": [
{
"lang": "en",
"time": "2026-10-21T08:41:10.000Z",
"value": "Reported to Red Hat."
},
{
"lang": "en",
"time": "2026-11-05T14:29:20.355Z",
"value": "Made public."
}
],
"title": "Gdb: gdbserver: heap disclosure and wild pointer in gdb_parse_agent_expr via untrusted agent-expression length",
"workarounds": [
{
"lang": "en",
"value": "There is no mitigation for this vulnerability. gdbserver has no authentication mechanism; exposure is limited only by network access to the gdbserver port.\n\n--- CME Mitigation Guidance (2026-11-06) ---\nDisclaimer: The following mitigation solutions are provided as a courtesy, pending the application of an official patch. This content was generated utilizing AI tools in conjunction with data from https://cmetaxonomy.org. Customers are advised to independently evaluate and test these temporary mitigations within their own infrastructure.\n\nThe highest-value action is to restrict network access to exposed gdbserver listening ports and eliminate untrusted agent-expression length handling in gdbserver: upgrade to the corresponding fixed Red Hat builds, which apply the documented input check, closing crafted agent-expression packet with declared length exceeding actual payload data. Until patched, this is a concern on Linux systems hosting gdbserver with an exposed listening port, so Restrict network access to the gdbserver listening port using host or network firewalls, limiting connectivity to trusted debugging clients only. As a compensating measure, Maintain SELinux in enforcing mode to confine the gdbserver process domain and limit host impact if heap disclosures are used to stage subsequent code execution. These controls limit blast radius and contain exploitation, but they do not fix the underlying length validation defect \u2014 apply the upstream patch to fully remediate.\n\nHighest-impact CME: CME-301 SELinux (Enforcing Mode) (medium)"
}
],
"x_generator": {
"engine": "cvelib 1.8.0"
},
"x_redhatCweChain": "CWE-822: Untrusted Pointer Dereference"
}
},
"cveMetadata": {
"assignerOrgId": "53f830b8-0a3f-465b-8143-3b8a9948e749",
"assignerShortName": "redhat",
"cveId": "CVE-2026-121996",
"datePublished": "2026-11-05T16:08:52.127Z",
"dateReserved": "2026-11-04T13:28:12.839Z",
"dateUpdated": "2026-11-06T19:55:34.343Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2",
"vulnerability-lookup:meta": {
"vulnrichment": {
"containers": {
"adp": [
{
"metrics": [
{
"other": {
"content": {
"id": "CVE-2026-121996",
"options": [
{
"Exploitation": "none"
},
{
"Automatable": "yes"
},
{
"Technical Impact": "partial"
}
],
"role": "CISA Coordinator",
"timestamp": "2026-11-05T18:52:10.802560Z",
"version": "2.0.3"
},
"type": "ssvc"
}
}
],
"providerMetadata": {
"dateUpdated": "2026-11-05T18:52:14.813Z",
"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"shortName": "CISA-ADP"
},
"title": "CISA ADP Vulnrichment"
}
],
"cna": {
"affected": [
{
"collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
"cpes": [
"cpe:/a:redhat:enterprise_linux:10"
],
"defaultStatus": "unaffected",
"packageName": "crash",
"product": "Red Hat Enterprise Linux 10",
"vendor": "Red Hat"
},
{
"collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
"cpes": [
"cpe:/a:redhat:enterprise_linux:10"
],
"defaultStatus": "affected",
"packageName": "gdb",
"product": "Red Hat Enterprise Linux 10",
"vendor": "Red Hat"
},
{
"collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
"cpes": [
"cpe:/o:redhat:rhel_els:6"
],
"defaultStatus": "affected",
"packageName": "gdb",
"product": "Red Hat Enterprise Linux 6",
"vendor": "Red Hat"
},
{
"collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
"cpes": [
"cpe:/o:redhat:rhel_els:7"
],
"defaultStatus": "affected",
"packageName": "gdb",
"product": "Red Hat Enterprise Linux 7",
"vendor": "Red Hat"
},
{
"collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
"cpes": [
"cpe:/a:redhat:enterprise_linux:8"
],
"defaultStatus": "unaffected",
"packageName": "crash",
"product": "Red Hat Enterprise Linux 8",
"vendor": "Red Hat"
},
{
"collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
"cpes": [
"cpe:/a:redhat:enterprise_linux:8"
],
"defaultStatus": "affected",
"packageName": "gcc-toolset-14-gdb",
"product": "Red Hat Enterprise Linux 8",
"vendor": "Red Hat"
},
{
"collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
"cpes": [
"cpe:/a:redhat:enterprise_linux:8"
],
"defaultStatus": "affected",
"packageName": "gcc-toolset-15-gdb",
"product": "Red Hat Enterprise Linux 8",
"vendor": "Red Hat"
},
{
"collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
"cpes": [
"cpe:/a:redhat:enterprise_linux:8"
],
"defaultStatus": "affected",
"packageName": "gdb",
"product": "Red Hat Enterprise Linux 8",
"vendor": "Red Hat"
},
{
"collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
"cpes": [
"cpe:/a:redhat:enterprise_linux:9"
],
"defaultStatus": "unaffected",
"packageName": "crash",
"product": "Red Hat Enterprise Linux 9",
"vendor": "Red Hat"
},
{
"collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
"cpes": [
"cpe:/a:redhat:enterprise_linux:9"
],
"defaultStatus": "affected",
"packageName": "gdb",
"product": "Red Hat Enterprise Linux 9",
"vendor": "Red Hat"
},
{
"collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
"cpes": [
"cpe:/a:redhat:hummingbird:1"
],
"defaultStatus": "affected",
"packageName": "gdb",
"product": "Red Hat Hardened Images",
"vendor": "Red Hat"
}
],
"credits": [
{
"lang": "en",
"value": "Red Hat would like to thank Pulkit Singh Singaria for reporting this issue."
}
],
"datePublic": "2026-11-05T14:29:20.355Z",
"descriptions": [
{
"lang": "en",
"value": "A length validation flaw in gdbserver\u0027s agent-expression parser allows an unauthenticated remote attacker to read uninitialized heap memory from the gdbserver process and cause a denial of service. Disclosed heap content includes addresses suitable for defeating ASLR in further exploitation."
}
],
"metrics": [
{
"other": {
"content": {
"namespace": "https://access.redhat.com/security/updates/classification/",
"value": "Important"
},
"type": "Red Hat severity rating"
}
},
{
"cvssV3_1": {
"attackComplexity": "LOW",
"attackVector": "NETWORK",
"availabilityImpact": "HIGH",
"baseScore": 8.2,
"baseSeverity": "HIGH",
"confidentialityImpact": "LOW",
"integrityImpact": "NONE",
"privilegesRequired": "NONE",
"scope": "UNCHANGED",
"userInteraction": "NONE",
"vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H",
"version": "3.1"
},
"format": "CVSS"
}
],
"problemTypes": [
{
"descriptions": [
{
"cweId": "CWE-822",
"description": "Untrusted Pointer Dereference",
"lang": "en",
"type": "CWE"
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-11-06T19:55:34.343Z",
"orgId": "53f830b8-0a3f-465b-8143-3b8a9948e749",
"shortName": "redhat"
},
"references": [
{
"tags": [
"vdb-entry",
"x_refsource_REDHAT"
],
"url": "https://access.redhat.com/security/cve/CVE-2026-121996"
},
{
"name": "RHBZ#2565678",
"tags": [
"issue-tracking",
"x_refsource_REDHAT"
],
"url": "https://bugzilla.redhat.com/show_bug.cgi?id=2565678"
}
],
"timeline": [
{
"lang": "en",
"time": "2026-10-21T08:41:10.000Z",
"value": "Reported to Red Hat."
},
{
"lang": "en",
"time": "2026-11-05T14:29:20.355Z",
"value": "Made public."
}
],
"title": "Gdb: gdbserver: heap disclosure and wild pointer in gdb_parse_agent_expr via untrusted agent-expression length",
"workarounds": [
{
"lang": "en",
"value": "There is no mitigation for this vulnerability. gdbserver has no authentication mechanism; exposure is limited only by network access to the gdbserver port.\n\n--- CME Mitigation Guidance (2026-11-06) ---\nDisclaimer: The following mitigation solutions are provided as a courtesy, pending the application of an official patch. This content was generated utilizing AI tools in conjunction with data from https://cmetaxonomy.org. Customers are advised to independently evaluate and test these temporary mitigations within their own infrastructure.\n\nThe highest-value action is to restrict network access to exposed gdbserver listening ports and eliminate untrusted agent-expression length handling in gdbserver: upgrade to the corresponding fixed Red Hat builds, which apply the documented input check, closing crafted agent-expression packet with declared length exceeding actual payload data. Until patched, this is a concern on Linux systems hosting gdbserver with an exposed listening port, so Restrict network access to the gdbserver listening port using host or network firewalls, limiting connectivity to trusted debugging clients only. As a compensating measure, Maintain SELinux in enforcing mode to confine the gdbserver process domain and limit host impact if heap disclosures are used to stage subsequent code execution. These controls limit blast radius and contain exploitation, but they do not fix the underlying length validation defect \u2014 apply the upstream patch to fully remediate.\n\nHighest-impact CME: CME-301 SELinux (Enforcing Mode) (medium)"
}
],
"x_generator": {
"engine": "cvelib 1.8.0"
},
"x_redhatCweChain": "CWE-822: Untrusted Pointer Dereference"
}
},
"cveMetadata": {
"assignerOrgId": "53f830b8-0a3f-465b-8143-3b8a9948e749",
"assignerShortName": "redhat",
"cveId": "CVE-2026-121996",
"datePublished": "2026-11-05T16:08:52.127Z",
"dateReserved": "2026-11-04T13:28:12.839Z",
"dateUpdated": "2026-11-06T19:55:34.343Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2"
}
}
}
Loading…
Loading…
Drag nodes to arrange them. Double-click a related vulnerability to open it, or a source to visit its link. The Physics button on the left tunes the layout and the simulation; the legend at the bottom left hides or shows nodes by kind and by sighting type.
Experimental. This forecast is provided for visualization only and may change without notice. Do not use it for operational decisions.
Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
Vulnerability timeline
Sightings and recorded dates, grouped by day · UTC
Loading timeline…
Loading…
Loading…
The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the
vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base
model, served locally by ML-Gateway.
They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
Loading…
Related by attack behaviour
Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.