CVE-2007-3377: Header.pm in Net::DNS before 0.60, a Perl module, (1) generates predictable sequence IDs with a fixed incremen

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MEDIUM 4.3DOWNGRADE

CVE-2007-3377 is a medium-severity flaw (CVSS 4.3) affecting net dns. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Header.pm in Net::DNS before 0.60, a Perl module, (1) generates predictable sequence IDs with a fixed increment and (2) can use the same starting ID for all child processes of a forking server, which allows remote attackers to spoof DNS responses, as originally reported for qpsmtp and spamassassin.

Why this priority

Public exploit reference

No fix is published yet: follow the downgrade or mitigation steps.

Risk facts

CVSS score	4.3 (Medium)
EPSS exploit chance	2.0% (top 19%)
CISA exploited list	No
Published	2007-06-25
Last modified	2026-06-16

Publisher (CNA): Red Hat, Inc. · Vendor: nlnet labs

Last updated 2026-06-16 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2007-06-25 21:30 UTCPublished CVE record published
2026-06-16 22:41 UTCUpdated Record last modified

nlnet labs net dns DOWNGRADE

Affected: 0.14 · 0.20 · 0.21 · 0.22 · 0.23 · 0.24 · 0.25 · 0.26

Fixed in: no fixed release known

Safe to downgrade to: a release before 0.14

1. Check installed version

apt-cache policy net-dns || rpm -q net-dns || net-dns --version

2. No fixed release: DOWNGRADE to a release before 0.14 (Debian / Ubuntu)

apt-cache madison net-dns sudo apt install net-dns=<VERSION_BEFORE_0.14> sudo apt-mark hold net-dns

2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list net-dns sudo dnf downgrade net-dns-<VERSION_BEFORE_0.14> sudo dnf versionlock add net-dns

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2007-3377?

net dns: downgrade or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2007-3377 being exploited?

CVE-2007-3377 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2007-3377 affect?

CVE-2007-3377 affects net dns. Severity is medium (CVSS 4.3). Header.pm in Net::DNS before 0.60, a Perl module, (1) generates predictable sequence IDs with a fixed increment and (2) can use the same starting ID for all child processes of a forking server, which allows remote attackers to spoof DNS res

How urgent is CVE-2007-3377?

Priority 40/100. Public exploit reference

Software pages

Perl vulnerabilities

Related CVEs

CVE-2007-6341 MEDIUM 5.0 DOWNGRADE Net/DNS/RR/A.pm in Net::DNS 0.60 build 654, as used in packages such as SpamAssassin and OTRS, allows remote a
CVE-2006-5521 HIGH 7.5 UPGRADE PHP remote file inclusion vulnerability in DNS/RR.php in Net_DNS 0.03 and earlier allows remote attackers to e

References

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