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CVE-2021-35525

PostSRSd before 1.11 allows a denial of service (subprocess hang) if Postfix sends certain long...

5.3 MediumFix available

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."

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
Low
Privileges needed
None
User interaction
None

What an attacker can affect

Confidentiality
None
Integrity
None
Availability
Low

Exploit likelihood

1.65%Up 0.6 points since Jun 29, 2021
90%50%10%1%

What each source reports

NVD Score used 5.3

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."

Record
CVE-2021-35525
CVSS 3.1
5.3 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
CVSS 2.0
5.0 MediumAV:N/AC:L/Au:N/C:N/I:N/A:P
Updated
2026-11-02
CVE List No score

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."

Record
CVE-2021-35525
Updated
2026-11-02
EUVDEUVD-2021-22161 No score

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."

Record
EUVD-2021-22161
Updated
2026-11-03
GitHub AdvisoriesGHSA-w799-rf9r-4rqc No score

PostSRSd before 1.11 allows a denial of service (subprocess hang) if Postfix sends certain long...

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."

Record
GHSA-w799-rf9r-4rqc
Updated
2026-11-02
OSV 5.3

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."

Record
CVE-2021-35525
CVSS 3.1
5.3 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
Updated
2026-11-02
OSVDEBIAN-CVE-2021-35525 5.3

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."

Record
DEBIAN-CVE-2021-35525
CVSS 3.1
5.3 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
Updated
2026-11-02
OSVUBUNTU-CVE-2021-35525 5.3

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."

Record
UBUNTU-CVE-2021-35525
CVSS 3.1
5.3 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
postsrsd
Debian:12
 before 1.10-2
1.10-2
postsrsd
Debian:13
 before 1.10-2
1.10-2
postsrsd
Debian:14
 before 1.10-2
1.10-2
postsrsd
Ubuntu:16.04:LTS
 All versions, plus listed versions
1.2-1
 None known
postsrsd
Ubuntu:18.04:LTS
 All versions, plus listed versions
1.4-11.4-1ubuntu0.1
 None known
postsrsd
Ubuntu:20.04:LTS
 All versions, plus listed versions
1.5-2
 None known
postsrsd
Ubuntu:22.04:LTS
 All versions, plus listed versions
1.10-2
 None known
postsrsd
Ubuntu:24.04:LTS
 All versions, plus listed versions
1.10-21.10-2.1build1
 None known
postsrsd
Ubuntu:25.10
 All versions, plus listed versions
1.10-2.2
 None known
postsrsd
Ubuntu:26.04:LTS
 All versions, plus listed versions
1.10-2.22.0.11-1
 None known

History

History
RecordedChangedSources
aliasesEUVD
first indexedCVE List, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2021-35525 is a medium vulnerability (CVSS 5.3) in Postsrsd Project Postsrsd, published June 28, 2021. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 1.65%, the 76th percentile. Fixed in postsrsd 1.10-2.

References

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