CVE-2026-107708

MIT krb5 through 1.22.2 contains a NULL pointer dereference vulnerability in the KDC's get_pac_princ_with_realm() that returns success while leaving the client principal NULL on malformed names. A malicious or compromised cross-realm trusted KDC can send an S4U2Proxy request with a PAC carrying a malformed client name to crash krb5kdc and deny authentication.

CVSS v3 4.9 MEDIUM

4.9^/10

CVSS v3 : MEDIUM

Vector :

Exploitability : 1.2 / Impact : 3.6

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required HIGH

User Interaction NONE

Confidentiality Impact NONE

Integrity Impact NONE

Availability Impact HIGH

Scope UNCHANGED

References

Link	Resource
https://github.com/krb5/krb5
https://github.com/krb5/krb5/blob/krb5-1.22.2-final/src/kdc/kdc_util.c#L639-L676
https://github.com/krb5/krb5/commit/a88a18cafa1040a0c4f9c8d08288fc98831ec86d
https://github.com/krb5/krb5/commit/f6e2c397ceda6467ebbaab8ed66d4895c9f1d6a7
https://github.com/krb5/krb5/pull/1510
https://www.vulncheck.com/advisories/mit-krb5-through-1.22.2-kdc-null-pointer-dereference-via-s4u2proxy-pac

Configurations

No configuration.

History

08 Oct 2026, 21:17

Type	Values Removed	Values Added
New CVE

Information

Published : 2026-10-08 21:17

Updated : 2026-10-14 02:16

NVD link : CVE-2026-107708

Mitre link : CVE-2026-107708

CVE.ORG link : CVE-2026-107708

JSON object : View

Products Affected

No product.

CWE

CWE-476

NULL Pointer Dereference

{"id": "CVE-2026-107708", "cveTags": [], "metrics": {"ssvcV203": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": {"id": "CVE-2026-107708", "role": "CISA Coordinator", "options": [{"exploitation": "none"}, {"automatable": "no"}, {"technicalImpact": "partial"}], "version": "2.0.3", "timestamp": "2026-10-14T01:18:41.034364Z"}}], "cvssMetricV31": [{"type": "Secondary", "source": "disclosure@vulncheck.com", "cvssData": {"scope": "UNCHANGED", "version": "3.1", "baseScore": 4.9, "attackVector": "NETWORK", "baseSeverity": "MEDIUM", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H", "integrityImpact": "NONE", "userInteraction": "NONE", "attackComplexity": "LOW", "availabilityImpact": "HIGH", "privilegesRequired": "HIGH", "confidentialityImpact": "NONE"}, "impactScore": 3.6, "exploitabilityScore": 1.2}], "cvssMetricV40": [{"type": "Secondary", "source": "disclosure@vulncheck.com", "cvssData": {"Safety": "NOT_DEFINED", "version": "4.0", "Recovery": "NOT_DEFINED", "baseScore": 6.9, "Automatable": "NOT_DEFINED", "attackVector": "NETWORK", "baseSeverity": "MEDIUM", "valueDensity": "NOT_DEFINED", "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X", "exploitMaturity": "NOT_DEFINED", "providerUrgency": "NOT_DEFINED", "userInteraction": "NONE", "attackComplexity": "LOW", "attackRequirements": "NONE", "privilegesRequired": "HIGH", "subIntegrityImpact": "NONE", "vulnIntegrityImpact": "NONE", "integrityRequirement": "NOT_DEFINED", "modifiedAttackVector": "NOT_DEFINED", "subAvailabilityImpact": "NONE", "vulnAvailabilityImpact": "HIGH", "availabilityRequirement": "NOT_DEFINED", "modifiedUserInteraction": "NOT_DEFINED", "modifiedAttackComplexity": "NOT_DEFINED", "subConfidentialityImpact": "NONE", "vulnConfidentialityImpact": "NONE", "confidentialityRequirement": "NOT_DEFINED", "modifiedAttackRequirements": "NOT_DEFINED", "modifiedPrivilegesRequired": "NOT_DEFINED", "modifiedSubIntegrityImpact": "NOT_DEFINED", "modifiedVulnIntegrityImpact": "NOT_DEFINED", "vulnerabilityResponseEffort": "NOT_DEFINED", "modifiedSubAvailabilityImpact": "NOT_DEFINED", "modifiedVulnAvailabilityImpact": "NOT_DEFINED", "modifiedSubConfidentialityImpact": "NOT_DEFINED", "modifiedVulnConfidentialityImpact": "NOT_DEFINED"}}]}, "affected": [{"source": "disclosure@vulncheck.com", "affectedData": [{"repo": "https://github.com/krb5/krb5", "vendor": "MIT", "product": "krb5", "versions": [{"status": "affected", "version": "0", "versionType": "custom", "lessThanOrEqual": "1.22.2"}], "packageURL": "pkg:github/krb5/krb5", "collectionURL": "https://github.com/krb5/krb5", "defaultStatus": "unaffected"}]}], "published": "2026-10-08T21:17:52.223", "references": [{"url": "https://github.com/krb5/krb5", "source": "disclosure@vulncheck.com"}, {"url": "https://github.com/krb5/krb5/blob/krb5-1.22.2-final/src/kdc/kdc_util.c#L639-L676", "source": "disclosure@vulncheck.com"}, {"url": "https://github.com/krb5/krb5/commit/a88a18cafa1040a0c4f9c8d08288fc98831ec86d", "source": "disclosure@vulncheck.com"}, {"url": "https://github.com/krb5/krb5/commit/f6e2c397ceda6467ebbaab8ed66d4895c9f1d6a7", "source": "disclosure@vulncheck.com"}, {"url": "https://github.com/krb5/krb5/pull/1510", "source": "disclosure@vulncheck.com"}, {"url": "https://www.vulncheck.com/advisories/mit-krb5-through-1.22.2-kdc-null-pointer-dereference-via-s4u2proxy-pac", "source": "disclosure@vulncheck.com"}], "vulnStatus": "Awaiting Analysis", "weaknesses": [{"type": "Secondary", "source": "disclosure@vulncheck.com", "description": [{"lang": "en", "value": "CWE-476"}]}], "descriptions": [{"lang": "en", "value": "MIT krb5 through 1.22.2 contains a NULL pointer dereference vulnerability in the KDC's get_pac_princ_with_realm() that returns success while leaving the client principal NULL on malformed names. A malicious or compromised cross-realm trusted KDC can send an S4U2Proxy request with a PAC carrying a malformed client name to crash krb5kdc and deny authentication."}], "lastModified": "2026-10-14T02:16:57.580", "sourceIdentifier": "disclosure@vulncheck.com"}