CVE-2025-21764VulnerabilityPublished 16 Jun 2025Updated 30 Jul 2026

Red Hat Security Advisory: kernel security update

Affects Red HatSource GCVE Database

Mentioned vulnerabilities

Not known to be exploited : upgrade the Red Hat redhat/kernel package to 10.2.0 soon.

Data as of 26 Oct 2026, 08:30 UTC

Severity

High

Rated by Threat Radar · No CVSS score from NVD or the CNA

EPSS: 0.2% chance of exploitation in 30 days – higher than 19% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 10.2.0

Exploitation evidence

Disclosed: evidence found.
CVE published 16 Jun 2025
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: 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 26 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade the Red Hat redhat/kernel package to 10.2.0.

Affected software

Product	Affected	Fixed in
Red Hatredhat/kernel`pkg:rpm/redhat/kernel`Other threats	Affected =10.0 <10.2.0	Fixed in 10.2.0

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

Red Hat has released updated kernel packages that fix these vulnerabilities. Users should apply the security update for Red Hat Enterprise Linux 10 as provided in advisory RHSA-2025:9079 and reboot their systems to ensure the fixes take effect. No additional mitigation steps are indicated beyond applying the official update and rebooting.

Description

The kernel packages contain the Linux kernel, the core of any Linux operating system. Security Fix(es): * kernel: ndisc: use RCU protection in ndisc_alloc_skb() (CVE-2025-21764) * kernel: ovl: fix UAF in ovl_dentry_update_reval by moving dput() in ovl_link_up (CVE-2025-21887) * kernel: keys: Fix UAF in key_put() (CVE-2025-21893) * kernel: cifs: Fix integer overflow while processing closetimeo mount option (CVE-2025-21962) * kernel: Bluetooth: L2CAP: Fix slab-use-after-free Read in l2cap_send_cmd (CVE-2025-21969) * kernel: cifs: Fix integer overflow while processing acdirmax mount option (CVE-2025-21963) * kernel: wifi: cfg80211: cancel wiphy_work before freeing wiphy (CVE-2025-21979) * kernel: smb: client: fix UAF in decryption with multichannel (CVE-2025-37750) For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

Impact

The vulnerabilities involve use-after-free conditions and integer overflows in critical kernel components, which could potentially lead to system crashes, memory corruption, or privilege escalation. The advisory rates the overall impact as Important (high severity). There are no known exploits in the wild at the time of this advisory.

Summary

The advisory covers eight distinct security fixes in the Linux kernel for Red Hat Enterprise Linux 10. These include CVE-2025-21764 (RCU protection in ndisc_alloc_skb), CVE-2025-21887 (UAF in overlayfs dentry update), CVE-2025-21893 (UAF in key_put), CVE-2025-21962 and CVE-2025-21963 (integer overflows in CIFS mount options), CVE-2025-21969 (use-after-free in Bluetooth L2CAP), CVE-2025-21979 (race condition in wifi cfg80211), and CVE-2025-37750 (UAF in SMB client decryption). These vulnerabilities affect core kernel components and could lead to memory corruption or denial of service if exploited. Red Hat has released updated kernel packages to address these issues, and a reboot is required to activate the patches.

CWE-416Use After Free (opens in a new tab)
Variant weaknessLikelihood of exploit: HighCWE Top 25 (2025): #7
The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory "belongs" to the code that operates on the new pointer.
Architecture and Design · Language Selection
Choose a language that provides automatic memory management.
Implementation · Attack Surface Reduction
When freeing pointers, be sure to set them to NULL once they are freed. However, the utilization of multiple or complex data structures may lower the usefulness of this strategy.
OWASP Cheat Sheets
XML Security (opens in a new tab)
Mass Assignment (opens in a new tab)
OWASP ASVS 4.0.3
V13.3.1 (opens in a new tab)
V5.1.4 (opens in a new tab)
V5.1.3 (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).
CWE-190Integer Overflow or Wraparound (opens in a new tab)
Base weaknessLikelihood of exploit: Medium
The product performs a calculation that can produce an integer overflow or wraparound when the logic assumes that the resulting value will always be larger than the original value. This occurs when an integer value is incremented to a value that is too large to store in the associated representation. When this occurs, the value may become a very small or negative number.
Requirements
Ensure that all protocols are strictly defined, such that all out-of-bounds behavior can be identified simply, and require strict conformance to the protocol.
Requirements · Language Selection
Use a language that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.
Architecture and Design · Libraries or Frameworks
Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.
OWASP Cheat Sheets
XML Security (opens in a new tab)
Mass Assignment (opens in a new tab)
OWASP ASVS 4.0.3
V5.4.3 (opens in a new tab)
V13.3.1 (opens in a new tab)
V5.1.4 (opens in a new tab)
Attack patterns
Forced Integer Overflow (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

Community reviews

Loading reviews…

Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 25 Jun 2026, 22:07 UTC

WeaknessesCWE-416, CWE-190

Technical details

References

Community reviews

Related threats