VulnerabilityPublished 27 Sep 2026Updated 30 Sep 2026

CVE-2026-100863: heymrun heym · Server-Side Request Forgery (SSRF)

Affects heymrun heymSource CVE Database V5

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Not known to be exploited · CVSS 5.3 Medium : upgrade to 0.0.91 when convenient.

Data as of 13 Nov 2026, 23:53 UTC

CVSS 4.0 base score

5.3Medium

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

EPSS

0.2% chance of exploitation in 30 days – higher than 15% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

Exploitation: No evidence of active exploitation and no public proof of concept
Automatable: Attackers cannot reliably automate steps 1–4 of the kill chain
Technical impact: Limited control over the software or limited information exposure

CISA SSVC assessment, 2026-09-30.

Patch

Available – fixed in 0.0.91

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

Attack Vector: Network
Attack Complexity: Low
Attack Requirements: None
Privileges Required: Low
User Interaction: None
Vulnerable system confidentiality: None
Vulnerable system integrity: None
Vulnerable system availability: None
Subsequent system confidentiality: Low
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: None: The successful attack does not depend on the deployment and execution conditions of the vulnerable system. The attacker can expect to be able to reach the vulnerability and execute the exploit under all or most instances of the vulnerability.
Privileges Required: Low: The attacker requires privileges that provide basic capabilities that are typically limited to settings and resources owned by a single low-privileged user. Alternatively, an attacker with Low privileges has the ability to access only non-sensitive resources.
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: None: There is no impact to availability within the Vulnerable System.
Subsequent system confidentiality: Low: There is some loss of confidentiality. Access to some restricted information is obtained, but the attacker does not have control over what information is obtained, or the amount or kind of loss is limited. The information disclosure does not cause a direct, serious loss to the Subsequent 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 27 Sep 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 13 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 heymrun heym to 0.0.91.

Affected software

Product	Affected	Fixed in
heymrunheym	Affected <0.0.91	Fixed in 0.0.91

AI-suggested

Upgrade to heym version 0.0.91 or later, which includes fixes that properly validate URLs and IP addresses to prevent SSRF attacks. No additional mitigation is required as the vendor has provided an official fix.

Description

Heym versions 0.0.90 and earlier contain two server-side request forgery (SSRF) vulnerabilities that allow an attacker to make unauthorized HTTP/HTTPS requests to internal or restricted network resources. These issues were fixed in version 0.0.91 by improving URL validation and IP address checks to block access to loopback, RFC1918, and cloud metadata endpoints, including IPv6 transition forms.

Impact

An attacker can exploit these SSRF vulnerabilities to make unauthorized requests to internal network services, including loopback interfaces, private RFC1918 addresses, and cloud metadata endpoints. This could lead to information disclosure or further network reconnaissance. The CVSS 4.0 base score is 5.3 (medium severity), reflecting network attack vector, low attack complexity, no privileges required, and no user interaction needed.

Summary

The vulnerability in heym versions 0.0.90 and earlier involves two SSRF egress gaps. The first gap is in the LLM image-edit input loader (_load_image_bytes), which fetched URLs using a bare httpx.get call with only a scheme check, allowing user-controlled URLs to bypass egress-pinning and access internal network resources. The second gap is in the _is_public_address function, which failed to properly unwrap IPv6 transition addresses such as NAT64, deprecated IPv4-compatible, and 6to4 addresses, allowing requests to bypass IP validation and access restricted IPv4 destinations. Version 0.0.91 addresses these issues by routing image loading through guarded HTTP clients, evaluating IPv6 transition addresses correctly, and outright refusing certain IPv6 prefixes associated with tunneling protocols.

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What to do

Affected software

Description

AI analysisMachine-generated, updated 3 Nov 2026, 05:28 UTC

Technical details

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