CVE-2026-48558
CVE-2026-48558 is a security flaw in SimpleHelp, remote-support software IT providers use to manage their customers’ computers. Attackers can get into SimpleHelp without a valid password. The US Cybersecurity and Infrastructure Security Agency (CISA) added it to its catalog of flaws known to be used in attacks on 29 Jun 2026.[1]
SimpleHelp is business software or equipment. Most families won’t have it, but attackers break into it to get inside companies, and from there to what those companies hold about their customers, patients and staff. Fixed in version 5.5.16 and 6.0 RC2 of SimpleHelp.
Description
CISA calls it an authentication bypass in SimpleHelp SimpleHelp. In its words: “SimpleHelp contains an authentication bypass vulnerability in the OIDC authentication flow. When OIDC authentication is configured, identity tokens submitted during login are accepted without verifying their cryptographic signature. In a vulnerable configuration, a remote, unauthenticated attacker can submit a forged token containing arbitrary identity claims to obtain a fully authenticated technician session. In some configurations, this may also allow bypass of multi-factor authentication.”[1]
The CVE record adds: “SimpleHelp versions 5.5.15 and prior and 6.0 pre-release versions contain an authentication bypass vulnerability in the OIDC authentication flow. When OIDC authentication is configured, identity tokens submitted during login are accepted without verifying their cryptographic signature. In a vulnerable configuration, a remote, unauthenticated attacker can submit a forged token containing arbitrary identity claims to obtain a fully authenticated technician session. In some configurations, this may also allow bypass of multi-factor authentication. No user interaction is required.”[2]
The underlying weakness is CWE-347, in MITRE’s list of common software weaknesses.
It scores 10.0 out of 10 on the Common Vulnerability Scoring System, which rates it critical, scored by the organisation that published the CVE using CVSS 3.1.[2]
Affected versions
NVD’s record lists these fixed versions: in each line, everything before the version shown is affected.[2]
| Product | Fixed in |
|---|---|
| SimpleHelp | 5.5.16 |
| SimpleHelp | 6.0 RC2 |
Most families won’t have SimpleHelp; it’s for whoever looks after IT at work.
Exploitation
CISA added it to its catalog of known exploited vulnerabilities on 29 Jun 2026, 17 days after it was made public. CISA lists a flaw only when it has reliable evidence of it being exploited, and gave US federal agencies until 2 Jul 2026 to fix it.[1]
FIRST’s Exploit Prediction Scoring System, which estimates how likely a flaw is to be used in attacks in the next 30 days from what it sees across the internet, puts it at 78%. That’s in the top 1% of the flaws it scores.[4]
CISA assesses it as automatable: attackers can run it against many targets at once.
CISA doesn’t say who was attacked, or how.
Fix
SimpleHelp has published a fix or advice.[3] CISA’s required action: “Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes).”[1]
- Check whether you use it.SimpleHelp is business software or equipment, so most families won’t have it. If you run a business, or work from home on company equipment, ask whoever looks after your IT.
- Send this page to your IT person.Ask them to confirm it’s fixed (fixed in version 5.5.16 and 6.0 RC2 of SimpleHelp), or not in use. CISA gave US government agencies until 2 Jul 2026 to fix it.
- If it can’t be fixed, take it offline.CISA’s advice when there’s no fix is to stop using the product, or take it off the internet, until there is one.
You can’t fix someone else’s server, but you can watch for what follows a break-in like this: a breach notice, a password reset you didn’t ask for, or a scam message that knows things it shouldn’t. HARD watches for those for you and your family.
Timeline
| Date | Event |
|---|---|
| The flaw is made public in the National Vulnerability Database, with a severity score of 10.0.[2] | |
| CISA adds it to its catalog of flaws known to be used in attacks.[1] | |
| CISA’s deadline for US government agencies to fix it.[1] | |
| FIRST puts the odds of it being used in attacks in the next 30 days at 78%.[4] |
See also
Other SimpleHelp flaws
- CVE-2024-57728: path traversal ·
- CVE-2024-57726: missing authorization ·
- CVE-2024-57727: path traversal ·
Similar flaws
- CVE-2026-5430, WSO2 products: path traversal ·
- CVE-2025-59718, Fortinet products: improper verification of cryptographic signature ·
- CVE-2020-2021, Palo Alto Networks PAN-OS: authentication bypass ·
- CVE-2022-20703, Cisco Small Business RV160, RV260, RV340, and RV345 Series Routers: small business RV series routers stack-based buffer overflow ·
- CVE-2020-1464, Microsoft Windows: spoofing ·
Every SimpleHelp flaw on CISA’s list · Everything added in June 2026
References
- ^ Cybersecurity and Infrastructure Security Agency. “SimpleHelp Authentication Bypass Vulnerability”. Known Exploited Vulnerabilities Catalog, added 29 Jun 2026.
- ^ National Institute of Standards and Technology. “CVE-2026-48558 Detail”. National Vulnerability Database, published 12 Jun 2026.
- ^ SimpleHelp. Advisories and fixes: simple-help.com, simple-help.com.
- ^ FIRST. “Exploit Prediction Scoring System”. EPSS 0.777, percentile 99.6, 31 Oct 2026.
- CVE Program. “CVE-2026-48558”. The official CVE record.
This article is built from CISA’s catalog (version 2026.10.30), NVD’s record and FIRST’s scores, kept in HARD’s database and checked every morning. The plain English is HARD’s.