CVE-2024-6409: OpenSSH · Signal Handler Race Condition
Affects OpenSSHSource GCVE Database
Not known to be exploited · 27% EPSS · CVSS 7.0 High.
Data as of 3 Nov 2026, 22:57 UTC
Thin evidence
One scorer or none| CNA (redhat) | CVSS 3.1 | 7.0 |
|---|
- EPSS
- 27.9% chance of exploitation in 30 days – higher than 98% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:HExploitation evidence
Disclosed: evidence found.
CVE published 8 Jul 2024
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 3 Nov 2026.
Description
A race condition vulnerability was discovered in how signals are handled by OpenSSH's server (sshd). If a remote attacker does not authenticate within a set time period, then sshd's SIGALRM handler is called asynchronously. However, this signal handler calls various functions that are not async-signal-safe, for example, syslog(). As a consequence of a successful attack, in the worst case scenario, an attacker may be able to perform a remote code execution (RCE) as an unprivileged user running the sshd server.
References
- access.redhat.com/errata/RHSA-2024:4457 (opens in a new tab)
- access.redhat.com/errata/RHSA-2024:4613 (opens in a new tab)
- access.redhat.com/errata/RHSA-2024:4716 (opens in a new tab)
- access.redhat.com/errata/RHSA-2024:4910 (opens in a new tab)
- access.redhat.com/errata/RHSA-2024:4955 (opens in a new tab)
- access.redhat.com/errata/RHSA-2024:4960 (opens in a new tab)
- access.redhat.com/errata/RHSA-2024:5444 (opens in a new tab)
- access.redhat.com/security/cve/CVE-2024-6409 (opens in a new tab)
- bugzilla.redhat.com/show_bug.cgi?id=2295085 (opens in a new tab)
- openwall.com/lists/oss-security/2024/07/08/2 (opens in a new tab)
- openwall.com/lists/oss-security/2024/07/09/2 (opens in a new tab)
- openwall.com/lists/oss-security/2024/07/09/5 (opens in a new tab)
- openwall.com/lists/oss-security/2024/07/10/1 (opens in a new tab)
- openwall.com/lists/oss-security/2024/07/10/2 (opens in a new tab)
- almalinux.org/blog/2024-07-09-cve-2024-6409/ (opens in a new tab)
- bugzilla.suse.com/show_bug.cgi?id=1227217 (opens in a new tab)
- explore.alas.aws.amazon.com/CVE-2024-6409.html (opens in a new tab)
- github.com/openela-main/openssh/commit/c00da7741d42029e49047dd89e266d91dcfbffa0 (opens in a new tab)
- security-tracker.debian.org/tracker/CVE-2024-6409 (opens in a new tab)
- security.netapp.com/advisory/ntap-20240712-0003/ (opens in a new tab)
- sig-security.rocky.page/issues/CVE-2024-6409/ (opens in a new tab)
- ubuntu.com/security/CVE-2024-6409 (opens in a new tab)
- suse.com/security/cve/CVE-2024-6409.html (opens in a new tab)
- cert-portal.siemens.com/productcert/html/ssa-398330.html (opens in a new tab)