How severe is CVE-2021-29416?

CVE-2021-29416 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is high, integrity none, and availability none.

Is CVE-2021-29416 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (63rd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-29416?

CVE-2021-29416 primarily affects Portswigger Burp Suite. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2021-29416?

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

When was CVE-2021-29416 published?

CVE-2021-29416 was published on 2021-03-29 and last updated on 2026-06-17.

CVE-2021-29416

CVE-2021-29416 is a medium-severity vulnerability in Portswigger Burp Suite with a CVSS 3.x base score of 6.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low.

Key facts

Severity: Medium (CVSS 3.x base score 6.5)
CVSS v2: 4.3
EPSS exploit prediction: 1% (63rd percentile)
Actively exploited: Not listed in CISA KEV
Affected product: Portswigger Burp Suite
Published: 2021-03-29
Last modified: 2026-06-17

Description

An issue was discovered in PortSwigger Burp Suite before 2021.2. During viewing of a malicious request, it can be manipulated into issuing a request that does not respect its upstream proxy configuration. This could leak NetNTLM hashes on Windows systems that fail to block outbound SMB.

Frequently asked questions

What is CVE-2021-29416?: An issue was discovered in PortSwigger Burp Suite before 2021.2. During viewing of a malicious request, it can be manipulated into issuing a request that does not respect its upstream proxy configuration. This could leak NetNTLM hashes on Windows systems that fail to block outbound SMB.
How severe is CVE-2021-29416?: CVE-2021-29416 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is high, integrity none, and availability none.
Is CVE-2021-29416 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (63rd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-29416?: CVE-2021-29416 primarily affects Portswigger Burp Suite. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-29416?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2021-29416 published?: CVE-2021-29416 was published on 2021-03-29 and last updated on 2026-06-17.

References

Affected products (2)

cpe:2.3:a:portswigger:burp_suite:*:*:*:*:community:*:*:*
cpe:2.3:a:portswigger:burp_suite:*:*:*:*:professional:*:*:*

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