How severe is CVE-2021-35525?

CVE-2021-35525 has a CVSS 3.x base score of 5.3, rated medium 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 low.

Is CVE-2021-35525 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (73rd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-35525?

CVE-2021-35525 affects Postsrsd Project Postsrsd. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-35525?

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

When was CVE-2021-35525 published?

CVE-2021-35525 was published on 2021-06-28 and last updated on 2026-06-17.

CVE-2021-35525

CVE-2021-35525 is a medium-severity vulnerability in Postsrsd Project Postsrsd with a CVSS 3.x base score of 5.3. 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 5.3)
CVSS v2: 5.0
EPSS exploit prediction: 2% (73rd percentile)
Actively exploited: Not listed in CISA KEV
Affected product: Postsrsd Project Postsrsd
Published: 2021-06-28
Last modified: 2026-06-17

Description

PostSRSd before 1.11 allows a denial of service (subprocess hang) if Postfix sends certain long data fields such as multiple concatenated email addresses. NOTE: the PostSRSd maintainer acknowledges "theoretically, this error should never occur ... I'm not sure if there's a reliable way to trigger this condition by an external attacker, but it is a security bug in PostSRSd nevertheless."

Frequently asked questions

What is CVE-2021-35525?: PostSRSd before 1.11 allows a denial of service (subprocess hang) if Postfix sends certain long data fields such as multiple concatenated email addresses. NOTE: the PostSRSd maintainer acknowledges "theoretically, this error should never occur ... I'm not sure if there's a reliable way to trigger this condition by an external attacker, but it is a security bug in PostSRSd nevertheless."
How severe is CVE-2021-35525?: CVE-2021-35525 has a CVSS 3.x base score of 5.3, rated medium 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 low.
Is CVE-2021-35525 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (73rd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-35525?: CVE-2021-35525 affects Postsrsd Project Postsrsd. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-35525?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2021-35525 published?: CVE-2021-35525 was published on 2021-06-28 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:postsrsd_project:postsrsd:*:*:*:*:*:*:*:*