How severe is CVE-2021-43611?

CVE-2021-43611 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2021-43611 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (64th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-43611?

CVE-2021-43611 affects Linphone Belle-sip. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-43611?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2021-43611 published?

CVE-2021-43611 was published on 2021-11-12 and last updated on 2026-06-17.

CVE-2021-43611

CVE-2021-43611 is a high-severity vulnerability in Linphone Belle-sip with a CVSS 3.x base score of 7.5. 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-404.

Key facts

Severity: High (CVSS 3.x base score 7.5)
CVSS v2: 5.0
EPSS exploit prediction: 1% (64th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-404
Affected product: Linphone Belle-sip
Published: 2021-11-12
Last modified: 2026-06-17

Description

Belledonne Belle-sip before 5.0.20 can crash applications such as Linphone via " \ " in the display name of a From header.

Frequently asked questions

What is CVE-2021-43611?: Belledonne Belle-sip before 5.0.20 can crash applications such as Linphone via " \ " in the display name of a From header.
How severe is CVE-2021-43611?: CVE-2021-43611 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2021-43611 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (64th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-43611?: CVE-2021-43611 affects Linphone Belle-sip. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-43611?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2021-43611 published?: CVE-2021-43611 was published on 2021-11-12 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:linphone:belle-sip:*:*:*:*:*:*:*:*

More vulnerabilities in Linphone Belle-sip

CVE-2021-43610 — High (CVSS 7.5): Belledonne Belle-sip before 5.0.20 can crash applications such as Linphone via an invalid From header (request URI…
CVE-2021-33056 — High (CVSS 7.5): Belledonne Belle-sip before 4.5.20, as used in Linphone and other products, can crash via an invalid From header in a…

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