CVE-2021-28041 — ssh-agent in OpenSSH before 8.5 has a double free that may be relevant in a few less-common...

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.

Remediation

Fixes and mitigations documented by the sources — linked to the original advisory.

• Documented patch — github.com (NIST National Vulnerability Database)
• Documented patch — www.openwall.com (NIST National Vulnerability Database)

First 24 hours

Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.

1. Identify exposed assets running the affected vendor/product/version combinations (Fedoraproject Fedora, Netapp Cloud Backup, Netapp Hci Compute Node Firmware…).
2. Apply the fixed version or the patch documented under Remediation.
3. Exploitation requires user interaction: tighten email/web filtering and warn affected users.
4. Search available logs for exploit probes matching the vulnerability class (memory corruption), errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

Attack characteristics

The CVSS vector, decoded. It describes the attack, not your exposure to it.

Every base score collected

Sources score independently and may disagree; each row says who scored it and under which version.

Weakness MITRE

Weakness class according to MITRE’s CWE catalog.

CWE-415 · Double Free

Other CVEs with this weakness →

EPSS over time FIRST

Oct 13, 2026 → Oct 14, 2026 · 2 reading(s) · max 3.42%

Detection

Read off the CVSS vector and the weakness class. Starting points, not tested rules.

• Prioritize edge telemetry for the network-reachable component (proxy, WAF, IDS/IPS).
• Correlate service crashes/restarts with inbound traffic; repeated crashes may indicate attempts.

Timeline

What happened to this CVE, newest first.

• 2026
• Record published
  Oct 14, 2026
• Fix documented
  Oct 14, 2026 · NIST National Vulnerability Database
• Affected products added · openbsd/openssh, fedoraproject/fedora, netapp/cloud backup, netapp/hci management node, netapp/solidfire, netapp/hci com
  Oct 14, 2026 · NIST National Vulnerability Database
• CVSS changed · 7.1
  Oct 14, 2026 · NIST National Vulnerability Database
• Source status changed · → Modified
  Oct 14, 2026 · NIST National Vulnerability Database
• Record created in this database
  Oct 14, 2026 · Alertas do Telegram
• 2021
• CVE published
  Mar 5, 2021 · mitre

Source activity

Repeated readings are counted rather than listed.

• 2× References added · Oct 14, 2026 – Oct 14, 2026
• 1× Official description updated · Oct 14, 2026 – Oct 14, 2026

References

14 on the record

• www.openssh.com/security.html
  Not Applicable, Vendor Advisory, x_refsource_MISC, NIST National Vulnerability Database
• www.openssh.com/txt/release-8.5
  Release Notes, Vendor Advisory, x_refsource_MISC, NIST National Vulnerability Database
• www.openwall.com/lists/oss-security/2021/03/03/1
  Mailing List, Patch, Third Party Advisory, x_refsource_MISC, NIST National Vulnerability Database
• github.com/openssh/openssh-portable/commit/e04fd6dde16de1cdc5a4d9946397ff60d9656
  Patch, Third Party Advisory, x_refsource_MISC, NIST National Vulnerability Database
• www.oracle.com//security-alerts/cpujul2021.html
  Third Party Advisory, x_refsource_MISC, NIST National Vulnerability Database
• security.gentoo.org/glsa/202105-35
  Third Party Advisory, vendor-advisory, x_refsource_GENTOO, NIST National Vulnerability Database
• lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/TXST
  vendor-advisory, x_refsource_FEDORA, NIST National Vulnerability Database
• lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/KQWGII
  GitHub Security Advisories
• lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/TXST2C
  GitHub Security Advisories
• cert-portal.siemens.com/productcert/html/ssa-398330.html
  NIST National Vulnerability Database
• github.com/advisories/GHSA-gp5m-rxrx-pfrj
  GitHub Security Advisories
• lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/KQWG
  vendor-advisory, x_refsource_FEDORA, NIST National Vulnerability Database
• security.netapp.com/advisory/ntap-20210416-0002/
  Third Party Advisory, x_refsource_CONFIRM, NIST National Vulnerability Database
• nvd.nist.gov/vuln/detail/CVE-2021-28041
  GitHub Security Advisories

Elsewhere on this site

Related CVEs (same products)

• High CVE-2026-106583 In ssh in OpenSSH before 10.6, a $ or \ character can occur in a command-line username, leading... 8d
• Low CVE-2026-106587 Type Confusion in Openbsd Openssh 8d
• Low CVE-2026-106589 In sshd in OpenSSH through 10.6, in certain environments such as QNX 6 and SCO… 8d
• Low CVE-2026-106588 In sshd in OpenSSH through 10.6, use of the macOS 27 (or later) SDK has the side effect… 8d
• Medium CVE-2026-106586 Always-Incorrect Control Flow Implementation in Openbsd Openssh 9d
• Medium CVE-2026-106585 In sshd and ssh in OpenSSH before 10.6, there is no check for whether the maximum packet length... 9d

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

• No CISA SSVC assessment.
• No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
• No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
• No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record

Text assembled only from the fields above — no additional claims.

What should defenders know first?

CVE-2021-28041 is "ssh-agent in OpenSSH before 8.5 has a double free that may be relevant in a few less-common...", rated High. It affects Fedora (Fedoraproject); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 7.1 describes technical severity. EPSS 3.42% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.

Comments

Moderated technical discussion. Read the community guidelines.

No comments yet.

Sign in or create an account to comment and suggest corrections.