Bug 2565842 (CVE-2026-121506)

Summary: CVE-2026-121506 ntpsec: ntpsec: Memory corruption via crafted NTS extension field
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
Status: NEW --- QA Contact:
Severity: high Docs Contact:
Priority: high    
Version: unspecifiedKeywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in NTPsec. An out-of-bounds memory read and write issue in the Network Time Security (NTS) client extension field parsing allows a remote attacker capable of sending server responses to trigger heap memory corruption. By supplying a crafted NTS extension field with an excessive nonce length, an attacker can crash the NTP service, leading to a Denial of Service (DoS), or potentially bypass authentication to alter the client's system time.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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Bug Depends On: 2567334, 2567335    
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Description OSIDB Bzimport 2026-11-03 14:52:59 UTC 
An out-of-bounds read and write in NTS client extension field parsing (extens_client_recv) in NTPsec before 1.2.5 allows a remote attacker who can send NTP server-mode replies to an NTS client to corrupt heap memory and crash ntpd, and, combined with the NTS-KE client out-of-bounds read fixed in 1.2.4, to bypass NTS authentication and set the client's time, via an NTS Authenticator and Encrypted Extension Fields field whose nonce length exceeds the field.