How severe is CVE-2021-32921?

CVE-2021-32921 has a CVSS 3.x base score of 5.9, rated medium severity. It is exploitable over network with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity none, and availability none.

Is CVE-2021-32921 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-2021-32921?

CVE-2021-32921 primarily affects Prosody. In total, 5 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2021-32921?

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

When was CVE-2021-32921 published?

CVE-2021-32921 was published on 2021-05-13 and last updated on 2026-06-17.

CVE-2021-32921

CVE-2021-32921 is a medium-severity vulnerability in Prosody with a CVSS 3.x base score of 5.9. 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-362.

Key facts

Severity: Medium (CVSS 3.x base score 5.9)
CVSS v2: 4.3
EPSS exploit prediction: 2% (73rd percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-362
Affected product: Prosody
Published: 2021-05-13
Last modified: 2026-06-17

Description

An issue was discovered in Prosody before 0.11.9. It does not use a constant-time algorithm for comparing certain secret strings when running under Lua 5.2 or later. This can potentially be used in a timing attack to reveal the contents of secret strings to an attacker.

Frequently asked questions

What is CVE-2021-32921?: An issue was discovered in Prosody before 0.11.9. It does not use a constant-time algorithm for comparing certain secret strings when running under Lua 5.2 or later. This can potentially be used in a timing attack to reveal the contents of secret strings to an attacker.
How severe is CVE-2021-32921?: CVE-2021-32921 has a CVSS 3.x base score of 5.9, rated medium severity. It is exploitable over network with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity none, and availability none.
Is CVE-2021-32921 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-2021-32921?: CVE-2021-32921 primarily affects Prosody. In total, 5 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-32921?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2021-32921 published?: CVE-2021-32921 was published on 2021-05-13 and last updated on 2026-06-17.

References

Affected products (5)

cpe:2.3:a:prosody:prosody:*:*:*:*:*:*:*:*
cpe:2.3:o:fedoraproject:fedora:32:*:*:*:*:*:*:*
cpe:2.3:o:fedoraproject:fedora:33:*:*:*:*:*:*:*
cpe:2.3:o:fedoraproject:fedora:34:*:*:*:*:*:*:*
cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*

More vulnerabilities in Prosody

CVE-2014-2745 — High (CVSS 7.8): Prosody before 0.9.4 does not properly restrict the processing of compressed XML elements, which allows remote…
CVE-2014-2744 — High (CVSS 7.8): plugins/mod_compression.lua in (1) Prosody before 0.9.4 and (2) Lightwitch Metronome through 3.4 negotiates stream…
CVE-2022-0217 — High (CVSS 7.5): It was discovered that an internal Prosody library to load XML based on libexpat does not properly restrict the XML…
CVE-2021-37601 — High (CVSS 7.5): muc.lib.lua in Prosody 0.11.0 through 0.11.9 allows remote attackers to obtain sensitive information (list of admins,…
CVE-2021-32920 — High (CVSS 7.5): Prosody before 0.11.9 allows Uncontrolled CPU Consumption via a flood of SSL/TLS renegotiation requests.
CVE-2021-32919 — High (CVSS 7.5): An issue was discovered in Prosody before 0.11.9. The undocumented dialback_without_dialback option in mod_dialback…

All CVEs affecting Prosody →

Other CWE-362 (Race Condition) vulnerabilities

CVE-2022-27626 — Critical (CVSS 10.0): A vulnerability regarding concurrent execution using shared resource with improper synchronization ('Race Condition')…
CVE-2015-8556 — Critical (CVSS 10.0): Local privilege escalation vulnerability in the Gentoo QEMU package before 2.5.0-r1.
CVE-2014-0703 — Critical (CVSS 10.0): Cisco Wireless LAN Controller (WLC) devices 7.4 before 7.4.110.0 distribute Aironet IOS software with a race condition…
CVE-2010-1228 — Critical (CVSS 10.0): Multiple race conditions in the sandbox infrastructure in Google Chrome before 4.1.249.1036 have unspecified impact and…
CVE-2008-6598 — Critical (CVSS 10.0): Multiple race conditions in WANPIPE before 3.3.6 have unknown impact and attack vectors related to "bri restart logic."
CVE-2026-46137 — Critical (CVSS 9.8): In the Linux kernel, the following vulnerability has been resolved: mptcp: pm: ADD_ADDR rtx: fix potential…

Browse all CWE-362 (Race Condition) vulnerabilities →