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Fencer Vulns
medium 5.0

CVE-2009-0021 json

NTP 4.2.4 before 4.2.4p5 and 4.2.5 before 4.2.5p150 does not properly check the return value from the OpenSSL EVP_VerifyFinal function, whi…

published 2009-01-07 17 y ago modified 2026-06-16 4 mo ago also EUVD-2009-0034

cvss
5.0
version 2.0, NVD
cisa kev
Not listed
not in CISA's catalog
epss
3.2%
EPSS 3.2% chance of exploitation in 30 days, percentile 88%
public exploits
0
none known

Summary

NTP 4.2.4 before 4.2.4p5 and 4.2.5 before 4.2.5p150 does not properly check the return value from the OpenSSL EVP_VerifyFinal function, which allows remote attackers to bypass validation of the certificate chain via a malformed SSL/TLS signature for DSA and ECDSA keys, a similar vulnerability to CVE-2008-5077.

Patch / fix

  • ntp Debian 11 1:4.2.4p4+dfsg-8

debian advisories DEBIAN-CVE-2009-0021

  • ntp RHEL 4 4.2.0.a.20040617-8.el4_7.1
  • ntp RHEL 5 4.2.2p1-9.el5_3.1

red hat advisories RHSA-2009:0046

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2009-0021 updated cvss 4.3

ntp incorrectly checks for malformed signatures

  • Red Hat Enterprise Linux (v. 5 server) ntp 4.2.2p1-9.el5_3.1 Red Hat Enterprise Linux AS version 4 ntp 4.2.0.a.20040617-8.el4_7.1 Red Hat Enterprise Linux Desktop (v. 5 client) ntp 4.2.2p1-9.el5_3.1 Red Hat Enterprise Linux Desktop version 4 ntp 4.2.0.a.20040617-8.el4_7.1 Red Hat Enterprise Linux ES version 4 ntp 4.2.0.a.20040617-8.el4_7.1 Red Hat Enterprise Linux WS version 4 ntp 4.2.0.a.20040617-8.el4_7.1
    fixed: vendor fix RHSA-2009:0046

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

3.22% chance of exploitation in the next 30 days, higher than 88% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
NVD 2.0 5.0 AV:N/AC:L/Au:N/C:P/I:N/A:N

Classification

Weakness

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.