VulnerabilityPublished 8 Nov 2026

CVE-2026-123598: hickory-dns · Insufficient Session Expiration

Affects hickory-dnsSource CVE Database V5

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Not known to be exploited · CVSS 6.3 Medium : upgrade to 0.26.2 when convenient.

Data as of 8 Nov 2026, 01:51 UTC

CVSS 4.0 base score

6.3Medium

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

Thin evidence

One scorer or none

CVSS scores by source
CNA (VulnCheck)	CVSS 4.0	6.3
CNA (VulnCheck)	CVSS 3.1	3.7

Patch: Available – fixed in 0.26.2

CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N

Attack Vector: Network
Attack Complexity: Low
Attack Requirements: Present
Privileges Required: None
User Interaction: None
Vulnerable system confidentiality: None
Vulnerable system integrity: None
Vulnerable system availability: Low
Subsequent system confidentiality: None
Subsequent system integrity: None
Subsequent system availability: None

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

Attack Vector: Network: The vulnerable system is bound to the network stack and the set of possible attackers extends beyond the other options listed below, 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: The attacker must take no measurable action to exploit the vulnerability. The attack requires no target-specific circumvention to exploit the vulnerability. An attacker can expect repeatable success against the vulnerable system.
Attack Requirements: Present: The successful attack depends on the presence of specific deployment and execution conditions of the vulnerable system that enable the attack. These include: a race condition must be won to successfully exploit the vulnerability (the successfulness of the attack is conditioned on execution conditions that are not under full control of the attacker, or the attack may need to be launched multiple times against a single target before being successful); the attacker must inject themselves into the logical network path between the target and the resource requested by the victim (e.g. vulnerabilities requiring an on-path attacker).
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files of the vulnerable system to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without interaction from any human user, other than the attacker.
Vulnerable system confidentiality: None: There is no loss of confidentiality within the Vulnerable System.
Vulnerable system integrity: None: There is no loss of integrity within the Vulnerable System.
Vulnerable system 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 Vulnerable System 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 Vulnerable System.
Subsequent system confidentiality: None: There is no loss of confidentiality within the Subsequent System or all confidentiality impact is constrained to the Vulnerable System.
Subsequent system integrity: None: There is no loss of integrity within the Subsequent System or all integrity impact is constrained to the Vulnerable System.
Subsequent system availability: None: There is no impact to availability within the Subsequent System or all availability impact is constrained to the Vulnerable System.

Definitions: FIRST CVSS v4.0 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 8 Nov 2026
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 7 Nov 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.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), 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

Upgrade hickory-dns to 0.26.2.

Affected software

Product	Affected	Fixed in
hickory-dnshickory-dns	Affected >=0.25.0 <=0.26.0-alpha.1	Fixed in–
hickory-dnshickory-dns	Affected >=0.26.0-alpha.1 <0.26.2	Fixed in 0.26.2
hickory-dnshickory-dns	Affected >=0.26.0-beta.1 <0.26.2	Fixed in 0.26.2
crates.iohickory-dns`pkg:cargo/hickory-dns`Other threats	Affected >=0.25.0 <=0.26.0-alpha.1 >=0.26.0-alpha.1 <0.26.2 >=0.26.0-beta.1 <0.26.2	Fixed in 0.26.2

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

AI-suggested

Upgrade affected Hickory DNS components to version 0.26.2 or later, where the caching behavior for DNSSEC-bogus answers has been corrected to use a short validation-failure TTL instead of the attacker-supplied TTL. No other mitigation is indicated.

Description

CVE-2026-123598 is a vulnerability in Hickory DNS validating recursor components where DNSSEC-bogus answers are cached using the attacker-supplied TTL, allowing a remote attacker to keep invalid DNS responses cached for up to 24 hours. This affects versions from 0.25.0 through 0.26.0-alpha.1, 0.26.0-alpha.1 before 0.26.2, and 0.26.0-beta.1 before 0.26.2. The issue is fixed in version 0.26.2.

Impact

An attacker can cause the DNS resolver to cache invalid DNSSEC responses for up to 24 hours, potentially leading to denial of service or incorrect DNS resolution during that period. The vulnerability does not require privileges or user interaction and can be exploited remotely. The CVSS 4.0 score is 6.3 (medium severity), reflecting network attack vector, low complexity, no privileges required, no user interaction, and limited impact on availability.

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 8 Nov 2026, 01:51 UTC

Technical details

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