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No exploitation reportedFix available

CVE-2021-37843

No exploitation reported by the sources we read.

  • Published2021-08-02
  • Fixed in5.0.5 · 4.0.12 · 3.6.6.1 · 3.6.6 · 3.5.6 · 2.5.9
  • WeaknessCWE-306

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

Description

The resolution SAML SSO apps for Atlassian products allow a remote attacker to login to a user account when only the username is known (i.e., no other authentication is provided). The fixed versions are for Jira: 3.6.6.1, 4.0.12, 5.0.5; for Confluence 3.6.6, 4.0.12, 5.0.5; for Bitbucket 2.5.9, 3.6.6, 4.0.12, 5.0.5; for Bamboo 2.5.9, 3.6.6, 4.0.12, 5.0.5; and for Fisheye 2.5.9.

Timeline

dates in UTC
  1. 2021-08-0219:15CVE publishedNVD

Observed activity

isMalicious corpus · updated 2026-10-23 18:48 UTC
Indicators tagged with this CVE, per day0 indicators over 7 days
Block these indicators
  • Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2021-37843?format=txt
  • CSV export: https://api.ismalicious.com/edl/cve/CVE-2021-37843?format=csv
  • TAXII collection of exploited CVEs
  • The EDL and CSV take an API key on the Pro plan.

Versions per branch

NVD
Atlassian saml single sign on
BranchAffectedFixed in
5.0≥ 5.0.0, < 5.0.55.0.5
4.0≥ 4.0.0, < 4.0.124.0.12
3.6< 3.6.6.13.6.6.1
3.6≥ 3.6.0, < 3.6.6.13.6.6.1
3.x≥ 3.0.0, < 3.6.63.6.6
3.5< 3.5.63.5.6
2.5< 2.5.92.5.9

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Fix

  1. Update Atlassian saml single sign on to 5.0.5 · 4.0.12 · 3.6.6.1 · 3.6.6 · 3.5.6 · 2.5.9

Detection

Nuclei template
none so far
ProjectDiscovery
Exploit-DB
no entry
Exploit-DB
Proof-of-concept repositories
none listed
PoC-in-GitHub

Sources

  • CNACVSS 3.19.8read 2026-10-23
  • NVDCVSS 3.19.8read 2026-10-23
  • NVDCVSS 2.07.5read 2026-10-23
  • NVDweakness (CWE)CWE-306read 2026-10-23
  • FIRST EPSSEPSS score1.5 %2026-10-22

Technical details

CVSS v3 Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Published
2021-08-02
Last Modified
2026-06-17
NVD status
Modified

Frequently asked questions

What is CVE-2021-37843?

The resolution SAML SSO apps for Atlassian products allow a remote attacker to login to a user account when only the username is known (i.e., no other authentication is provided). The fixed versions are for Jira: 3.6.6.1, 4.0.12, 5.0.5; for Confluence 3.6.6, 4.0.12, 5.0.5; for Bitbucket 2.5.9, 3.6.6, 4.0.12, 5.0.5; for Bamboo 2.5.9, 3.6.6, 4.0.12, 5.0.5; and for Fisheye 2.5.9.

Is CVE-2021-37843 actively exploited?

Active exploitation of CVE-2021-37843 has not been confirmed. Its EPSS score was 1.5% on 2026-10-22, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2021-37843?

CVE-2021-37843 has a CVSS v3 base score of 9.8 (CRITICAL severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

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