How severe is CVE-2009-4409?

CVE-2009-4409 has a CVSS 2.0 base score of 2.6, rated low severity.

Is CVE-2009-4409 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (68th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2009-4409?

CVE-2009-4409 primarily affects Iij Seil/b1. In total, 11 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2009-4409?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2009-4409 published?

CVE-2009-4409 was published on 2009-12-23 and last updated on 2026-06-16.

CVE-2009-4409

CVE-2009-4409 is a low-severity vulnerability in Iij Seil/b1 with a CVSS 2.0 base score of 2.6. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-287.

Key facts

Severity: Low (CVSS 2.0 base score 2.6)
EPSS exploit prediction: 1% (68th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-287
Affected product: Iij Seil/b1
Published: 2009-12-23
Last modified: 2026-06-16

Description

The (1) CHAP and (2) MS-CHAP-V2 authentication capabilities in the PPP Access Concentrator (PPPAC) function in Internet Initiative Japan SEIL/B1 firmware 1.00 through 2.52 use the same challenge for each authentication attempt, which allows remote attackers to bypass authentication via a replay attack.

Frequently asked questions

What is CVE-2009-4409?: The (1) CHAP and (2) MS-CHAP-V2 authentication capabilities in the PPP Access Concentrator (PPPAC) function in Internet Initiative Japan SEIL/B1 firmware 1.00 through 2.52 use the same challenge for each authentication attempt, which allows remote attackers to bypass authentication via a replay attack.
How severe is CVE-2009-4409?: CVE-2009-4409 has a CVSS 2.0 base score of 2.6, rated low severity.
Is CVE-2009-4409 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (68th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2009-4409?: CVE-2009-4409 primarily affects Iij Seil/b1. In total, 11 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2009-4409?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2009-4409 published?: CVE-2009-4409 was published on 2009-12-23 and last updated on 2026-06-16.

References

Affected products (11)

cpe:2.3:h:iij:seil\/b1:1.00:*:*:*:*:*:*:*
cpe:2.3:h:iij:seil\/b1:2.01:*:*:*:*:*:*:*
cpe:2.3:h:iij:seil\/b1:2.10:*:*:*:*:*:*:*
cpe:2.3:h:iij:seil\/b1:2.20:*:*:*:*:*:*:*
cpe:2.3:h:iij:seil\/b1:2.30:*:*:*:*:*:*:*
cpe:2.3:h:iij:seil\/b1:2.40:*:*:*:*:*:*:*
cpe:2.3:h:iij:seil\/b1:2.41:*:*:*:*:*:*:*
cpe:2.3:h:iij:seil\/b1:2.42:*:*:*:*:*:*:*
cpe:2.3:h:iij:seil\/b1:2.50:*:*:*:*:*:*:*
cpe:2.3:h:iij:seil\/b1:2.51:*:*:*:*:*:*:*
cpe:2.3:h:iij:seil\/b1:2.52:*:*:*:*:*:*:*

More vulnerabilities in Iij Seil/b1

CVE-2009-4292 — Critical (CVSS 9.3): Buffer overflow in the URL filtering function in Internet Initiative Japan SEIL/X1, SEIL/X2, and SEIL/B1 firmware 2.40…
CVE-2011-0454 — High (CVSS 8.3): Buffer overflow in the PPP Access Concentrator (PPPAC) on the SEIL/x86 with firmware 1.00 through 1.61, SEIL/B1 with…
CVE-2015-0887 — High (CVSS 7.1): npppd in the PPP Access Concentrator (PPPAC) on SEIL SEIL/x86 Fuji routers 1.00 through 3.30, SEIL/X1 routers 3.50…
CVE-2009-4293 — High (CVSS 7.1): Internet Initiative Japan SEIL/X1, SEIL/X2, and SEIL/B1 firmware 2.30 through 2.51, when NAT is enabled, allows remote…
CVE-2013-4709 — Medium (CVSS 6.8): Buffer overflow in the PPP Access Concentrator (PPPAC) on the SEIL/x86 with firmware before 2.82, SEIL/X1 with firmware…
CVE-2014-2004 — Medium (CVSS 5.0): The PPP Access Concentrator (PPPAC) on SEIL SEIL/x86 routers 1.00 through 3.10, SEIL/X1 routers 1.00 through 4.50,…

All CVEs affecting Iij Seil/b1 →

Other CWE-287 (Improper Authentication) vulnerabilities

CVE-2026-45480 — Critical (CVSS 10.0): Improper authentication in Azure Active Directory allows an unauthorized attacker to elevate privileges over a network.
CVE-2026-46389 — Critical (CVSS 10.0): UDS Identity Config builds the Keycloak configuration image (realm, plugins, theme, truststore, JARs) consumed by UDS…
CVE-2026-10611 — Critical (CVSS 10.0): An authentication bypass vulnerability exists in MISP when LDAP mixed authentication is enabled with OTP enforcement.…
CVE-2026-47280 — Critical (CVSS 10.0): Improper authentication in Azure Resource Manager (ARM) allows an unauthorized attacker to elevate privileges over a…
CVE-2026-42822 — Critical (CVSS 10.0): Improper authentication in Azure Local Disconnected Operations allows an unauthorized attacker to elevate privileges…
CVE-2026-20182 — Critical (CVSS 10.0): May 2026: This security advisory provides the details and fix information for a vulnerability that was discovered and…

Browse all CWE-287 (Improper Authentication) vulnerabilities →