VulnerabilityPublished 4 Aug 2025Updated 26 Feb 2026

CVE-2025-21120: Dell Avamar Server · Trusting HTTP Permission Methods on the Server Side

Affects Dell Avamar ServerSource CVE Database V5

Not known to be exploited · CVSS 8.3 High.

Data as of 26 Oct 2026, 14:05 UTC

CVSS 3.1 base score

8.3High

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.3% chance of exploitation in 30 days – higher than 24% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:L

Attack Vector: Network
Attack Complexity: Low
Privileges Required: Low
User Interaction: None
Scope: Unchanged
Confidentiality: High
Integrity: High
Availability: Low

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: Low: The attacker is authorized with (i.e., requires) privileges that provide basic user capabilities that could normally affect only settings and files owned by a user. Alternatively, an attacker with Low privileges may have the ability to cause an impact only to non-sensitive resources.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: High: There is total loss of confidentiality, resulting in all resources within the impacted component being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact.
Integrity: High: There is a total loss of integrity, or a complete loss of protection. For example, the attacker is able to modify any/all files protected by the impacted component. Alternatively, only some files can be modified, but malicious modification would present a direct, serious consequence to the impacted component.
Availability: Low: Performance is reduced or there are interruptions in resource availability. Even if repeated exploitation of the vulnerability is possible, the attacker does not have the ability to completely deny service to legitimate users. The resources in the impacted component are either partially available all of the time, or fully available only some of the time, but overall there is no direct, serious consequence to the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 4 Aug 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 or the CVSS exploit maturity 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

Affected software

Product	Affected	Fixed in
Dell Avamar Server	Affected >=19.8 <=19.10	Fixed in–

AI-suggested

To mitigate CVE-2025-21120, organizations should immediately apply the official patch 338904 provided by Dell for Avamar Server versions 19.8 through 19.10. Until patching is complete, implement strict network segmentation and firewall rules to restrict access to Avamar Server management interfaces to trusted administrative networks only. Employ strong authentication and authorization controls to limit low-privileged user access. Monitor network traffic for unusual HTTP methods or anomalous access patterns targeting Avamar servers. Conduct regular audits of server configurations to ensure HTTP methods are validated server-side and not blindly trusted. Additionally, consider deploying Web Application Firewalls (WAFs) with custom rules to block suspicious HTTP methods or malformed requests. Educate IT and security teams about this vulnerability to ensure rapid detection and response. Finally, maintain up-to-date backups and incident response plans to minimize impact if exploitation occurs.

Description

Dell Avamar, versions prior to 19.10 SP1 with patch 338904, contains a Trusting HTTP Permission Methods on the Server-Side vulnerability in Security. A low privileged attacker with remote access could potentially exploit this vulnerability, leading to Information exposure.

Impact

The exploitation of CVE-2025-21120 can lead to unauthorized disclosure of sensitive information stored or processed by Dell Avamar Server. This can compromise the confidentiality and integrity of backup data, potentially exposing critical business information, intellectual property, or personal data. Since Avamar is widely used for enterprise backup and recovery, attackers gaining access to this information could leverage it for further attacks, including ransomware or data theft campaigns. The low complexity and remote exploitability increase the likelihood of attacks, especially in environments where network access controls are insufficient. Although availability impact is low, the breach of confidentiality and integrity can have severe operational and reputational consequences. Organizations in sectors such as finance, healthcare, government, and large enterprises that rely heavily on Avamar for data protection are particularly vulnerable. The lack of known exploits in the wild currently reduces immediate risk but does not eliminate the threat, as attackers may develop exploits rapidly once details are public.

CWE-650Trusting HTTP Permission Methods on the Server Side (opens in a new tab)
Variant weaknessLikelihood of exploit: HighOWASP Top 10 A04:2021: Insecure Design (opens in a new tab)
The server contains a protection mechanism that assumes that any URI that is accessed using HTTP GET will not cause a state change to the associated resource. This might allow attackers to bypass intended access restrictions and conduct resource modification and deletion attacks, since some applications allow GET to modify state.
System Configuration
Configure ACLs on the server side to ensure that proper level of access control is defined for each accessible resource representation.
OWASP Cheat Sheets
REST Assessment (opens in a new tab)
REST Security (opens in a new tab)
Cross-Site Request Forgery Prevention (opens in a new tab)
OWASP ASVS 4.0.3
V13.2.1 (opens in a new tab)
V13.2.5 (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

dell.com/support/kbdoc/en-us/000347698/dsa-2025-271-security-update-for-dell-avamar-and-dell-avamar-virtual-edition-multiple-vulnerabilities (opens in a new tab)

Community reviews

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 27 Feb 2026, 00:45 UTC

WeaknessesCWE-650

Technical details

References

Community reviews

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