CVE-2008-3903: Asterisk Open Source 1.2.x before 1.2.32, 1.4.x before 1.4.24.1, and 1.6.0.x before 1.6.0.8; Asterisk Business

Routine

LOW 3.5DOWNGRADEDOWNGRADE

CVE-2008-3903 is a low-severity flaw (CVSS 3.5) affecting p b x, pbx. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Asterisk Open Source 1.2.x before 1.2.32, 1.4.x before 1.4.24.1, and 1.6.0.x before 1.6.0.8; Asterisk Business Edition A.x.x, B.x.x before B.2.5.8, C.1.x.x before C.1.10.5, and C.2.x.x before C.2.3.3; s800i 1.3.x before 1.3.0.2; and Trixbox PBX 2.6.1, when Digest authentication and authalwaysreject are enabled, generates different responses depending on whether a SIP username is valid, which allows remote attackers to enumerate valid usernames.

Why this priority

No elevated risk signals yet

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

Risk facts

CVSS score	3.5 (Low)
EPSS exploit chance	1.9% (top 21%)
CISA exploited list	No
Weakness	CWE-200
Published	2008-09-04
Last modified	2026-06-16

Publisher (CNA): MITRE · Vendor: asterisk · trixbox

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

Am I affected?

Timeline

2008-09-04 19:41 UTCPublished CVE record published
2026-06-16 22:56 UTCUpdated Record last modified

asterisk p b x DOWNGRADE

Affected: 1.2 · 1.2.22 · 1.4.21.1 · 1.6

Fixed in: no fixed release known

Safe to downgrade to: a release before 1.2

1. Check installed version

apt-cache policy p-b-x || rpm -q p-b-x || p-b-x --version

2. No fixed release: DOWNGRADE to a release before 1.2 (Debian / Ubuntu)

apt-cache madison p-b-x sudo apt install p-b-x=<VERSION_BEFORE_1.2> sudo apt-mark hold p-b-x

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

dnf --showduplicates list p-b-x sudo dnf downgrade p-b-x-<VERSION_BEFORE_1.2> sudo dnf versionlock add p-b-x

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.

trixbox pbx DOWNGRADE

Affected: 2.6.1

Fixed in: no fixed release known

Safe to downgrade to: a release before 2.6.1

1. Check installed version

apt-cache policy pbx || rpm -q pbx || pbx --version

2. No fixed release: DOWNGRADE to a release before 2.6.1 (Debian / Ubuntu)

apt-cache madison pbx sudo apt install pbx=<VERSION_BEFORE_2.6.1> sudo apt-mark hold pbx

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

dnf --showduplicates list pbx sudo dnf downgrade pbx-<VERSION_BEFORE_2.6.1> sudo dnf versionlock add pbx

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-2008-3903?

p b x: downgrade or apply the listed mitigation; pbx: downgrade or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2008-3903 being exploited?

CVE-2008-3903 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-2008-3903 affect?

CVE-2008-3903 affects p b x, pbx. Severity is low (CVSS 3.5). Asterisk Open Source 1.2.x before 1.2.32, 1.4.x before 1.4.24.1, and 1.6.0.x before 1.6.0.8; Asterisk Business Edition A.x.x, B.x.x before B.2.5.8, C.1.x.x before C.1.10.5, and C.2.x.x before C.2.3.3; s800i 1.3.x before 1.3.0.2; and Trixbox

How urgent is CVE-2008-3903?

Priority 32/100. No elevated risk signals yet.

References

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