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TI-2026-84261 Aliases CVE-2026-121506GHSA-28fm-m2x6-h5pf

Out-of-bounds write in NTPsec NTS extension field parsing

Priority LOW 33CWE-787Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
High
Impact type
—
Confidentiality · integrity · availability
None · High · High
Fix status
Fixed

Attack profile from CVSS 3.1 · CNA. Fix status from CNA.

Summary

NTPsec from 1.1.4 before 1.2.5 contains an out-of-bounds write (CWE-787) in NTS client extension field parsing. A remote attacker who can send NTP server-mode replies to an NTS client can corrupt heap memory and crash ntpd. Combined with an out-of-bounds read in NTS-KE client code fixed in 1.2.4, the attacker can bypass NTS authentication and set the client's time.

Written with Claude Haiku 5.5 from the sources below · 2026-11-04

Description from the CNA

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.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00449 39th percentileScored 2026-11-07
Fix Fixed NTPsec (NTPsec): 1.2.5

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
No
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
NTPsecNTPsec1.1.4 to before 1.2.51.2.5Patch availableCNA
  • NTPsec VendorNTPsec Affected 1.1.4 to before 1.2.5 Fixed in 1.2.5 Patch available CNA

Remediation

Update NTPsec to version 1.2.5, which fixes this issue.

Written with Claude Haiku 5.5 from the sources below · 2026-11-04

  • Fix · CNA NTPsec (NTPsec) Fixed in 1.2.5

Vendor assessments

Red Hat

Red Hat's page for this CVE →

Not affected: 1 product
  • Red Hat

Timeline

  1. 2026-11-03 Threatist record created from CVE-2026-121506
  2. 2026-11-03 CISA SSVC decision points changed
  3. 2026-11-03 Priority changed: MEDIUM → LOW
  4. 2026-11-03 Alias added: GHSA-28fm-m2x6-h5pf
  5. 2026-11-04 Affected versions changed · Red Hat
  6. 2026-11-04 CVSS score added · Red Hat

References

Other 2

  • TI-2019-04513 An issue was discovered in NTPsec before 1.1.3. CVSS 3.0CRITICAL 9.1
  • TI-2019-04514 An issue was discovered in NTPsec before 1.1.3. CVSS 3.0CRITICAL 9.1
  • TI-2026-42067 gpsd gpsprof Command Injection via gnuplot plot title subtype field CVSS 4.0HIGH 8.4
  • TI-2019-04515 An issue was discovered in NTPsec before 1.1.3. CVSS 3.0MEDIUM 6.5
  • TI-2019-04512 An issue was discovered in NTPsec before 1.1.3. CVSS 3.0MEDIUM 6.5
  • TI-2026-78850 Out-of-bounds read in NTPsec ntpd NTS extension field parsing CVSS 3.1HIGH 7.5
See all 14 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences