DaystoPatch

SolarWindsExploited incident

SolarWinds Web Help Desk deserialization RCE and security control bypass (WHD 2026.1)

CVE-2025-40551, CVE-2025-40536Critical, CVSS 9.8In CISA's Known Exploited Vulnerabilities catalog since 3 Feb 2026

FixedFixed for every supported version on the day it became public.

Response

Silence
same day
First public report to first vendor statement
Exposure
same day
First public report to first fix
Follow-through
same day
First public report to a fix for every supported version
  • Vendor silent
  • Vendor statement, no fix
  • Fixed for some versions
  • Fixed when disclosed
  • Date only, no time of day

Timeline and evidence

Open a moment to see its source and archived quote.

  1. First public report

    date only

    SolarWinds Trust Center advisory CVE-2025-40551CuratedQuote verified

    01/28/2026

    Value of the advisory's 'First Published' field. Reported privately by Horizon3.ai; the vendor advisory was the first public signal. Exploitation became public in early Feb 2026 (KEV 2026-02-03; Huntress report Feb 8, 2026; Microsoft report).

    Recorded time
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    Origin
    Curated. Found by a researcher, with a verbatim quote and link.
    Quote check
    Found in the archived copy
    Snapshot
    sha256:5870eb7939c851b3…
    Used in metrics
    Yes
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    5 more sources for this moment
    SolarWinds advisory CVE-2025-40536ClaimedQuote verified28 Jan 2026

    Advisory Details Severity High Advisory ID CVE-2025-40536 First Published 01/28/2026 Fixed Version SolarWinds Web Help Desk 2026.1 CVSS Score CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H Download PDF Send an Email SolarWinds

    The vendor's own disclosure.

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    Claimed. The date the source gives.
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    Found in the archived copy
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    sha256:98b1fd3ceaef0834…
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    CVE.org record CVE-2025-40536ClaimedQuote verified28 Jan 2026, 07:30 UTC

    SolarWinds Web Help Desk was found to be susceptible to a security control bypass vulnerability that if exploited, could allow an unauthenticated attacker to gain access to certain restricted

    CVE record published.

    Recorded time
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    To the minute
    Origin
    Claimed. The date the source gives.
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    Found in the archived copy
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    sha256:9942ca0e3c197805…
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    No, kept for the record
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    Bluesky postClaimedQuote not checked yet28 Jan 2026, 10:01 UTC

    🔴 CVE-2025-40551 - Critical (9.8)

    Earliest third-party post we hold.

    Source
    Bluesky post social
    Recorded time
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    To the minute
    Origin
    Claimed. The date the source gives.
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    Not checked yet
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    No archived snapshot
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    CISA KEV (CVE-2025-40551)ClaimedQuote verified3 Feb 2026

    SolarWinds Web Help Desk Deserialization of Untrusted Data Vulnerability

    Added to CISA's KEV catalog on 2026-02-03.

    Recorded time
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    Claimed. The date the source gives.
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    Found in the archived copy
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    sha256:ef8fffede5c47200…
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    No, kept for the record
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    CISA KEV (CVE-2025-40536)ClaimedQuote verified12 Feb 2026

    SolarWinds Web Help Desk Security Control Bypass Vulnerability

    Added to CISA's KEV catalog on 2026-02-12.

    Recorded time
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    Claimed. The date the source gives.
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    Found in the archived copy
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    sha256:ef8fffede5c47200…
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    No, kept for the record
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  2. Vendor statement

    date onlysame day

    SolarWinds advisory CVE-2025-40536ClaimedQuote verified

    Advisory Details Severity High Advisory ID CVE-2025-40536 First Published 01/28/2026 Fixed Version SolarWinds Web Help Desk 2026.1 CVSS Score CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H Download PDF Send an Email SolarWinds

    Recorded time
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    Date only (no time of day is shown)
    Origin
    Claimed. The date the source gives.
    Quote check
    Found in the archived copy
    Snapshot
    sha256:98b1fd3ceaef0834…
    Used in metrics
    Yes
    Dispute this timestamp
    2 more sources for this moment
    SolarWinds Trust Center advisory CVE-2025-40536CuratedQuote verified28 Jan 2026

    01/28/2026

    'First Published' field of the CVE-2025-40536 advisory.

    Recorded time
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    Date only (no time of day is shown)
    Origin
    Curated. Found by a researcher, with a verbatim quote and link.
    Quote check
    Found in the archived copy
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    sha256:98433c518b07ff09…
    Used in metrics
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    SolarWinds Trust Center advisory CVE-2025-40551CuratedQuote verified28 Jan 2026

    01/28/2026

    'First Published' field; the companion CVE-2025-40536 advisory carries the same First Published date (01/28/2026).

    Recorded time
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    Date only (no time of day is shown)
    Origin
    Curated. Found by a researcher, with a verbatim quote and link.
    Quote check
    Found in the archived copy
    Snapshot
    sha256:5870eb7939c851b3…
    Used in metrics
    No, kept for the record
    Dispute this timestamp

  3. First workaround

    No official mitigation found yet.

  4. First fix

    date onlysame day

    SolarWinds WHD 2026.1 release notesCuratedQuote verified

    Release date: January 28, 2026

    WHD 2026.1 fixes CVE-2025-40536, CVE-2025-40537, CVE-2025-40551, CVE-2025-40552, CVE-2025-40553 and CVE-2025-40554 per its security table.

    Recorded time
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    Origin
    Curated. Found by a researcher, with a verbatim quote and link.
    Quote check
    Found in the archived copy
    Snapshot
    sha256:9085f72afce364b5…
    Used in metrics
    Yes
    Dispute this timestamp
    2 more sources for this moment
    SolarWinds advisory CVE-2025-40536ClaimedQuote verified28 Jan 2026

    First Published 01/28/2026

    advisory published with fixed version: SolarWinds Web Help Desk 2026.1

    Recorded time
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    Claimed. The date the source gives.
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    Found in the archived copy
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    sha256:f34c3a71340e67e3…
    Used in metrics
    No, kept for the record
    Dispute this timestamp
    SolarWinds advisory CVE-2025-40551ClaimedQuote verified28 Jan 2026

    First Published 01/28/2026

    advisory published with fixed version: SolarWinds Web Help Desk 2026.1

    Recorded time
    Precision
    Date only (no time of day is shown)
    Origin
    Claimed. The date the source gives.
    Quote check
    Found in the archived copy
    Snapshot
    sha256:5870eb7939c851b3…
    Used in metrics
    No, kept for the record
    Dispute this timestamp

  5. Fixed for all versions

    date onlysame day

    SolarWinds WHD 2026.1 release notesCuratedQuote verified

    Release date: January 28, 2026

    Single fixed release (2026.1) for all affected versions ('SolarWinds Web Help Desk 12.8.8 HF1 and all previous versions'); WHD has one supported line.

    Recorded time
    Precision
    Date only (no time of day is shown)
    Origin
    Curated. Found by a researcher, with a verbatim quote and link.
    Quote check
    Found in the archived copy
    Snapshot
    sha256:9085f72afce364b5…
    Used in metrics
    Yes
    Dispute this timestamp

Send this to your boss

No brief for this incident yet. We write one for every open incident and every critical bug exploited before a fix.

Affected products

  • SolarWinds Web Help Desk
How we built this timeline

Grouped because both CVEs were fixed in the same release (WHD 2026.1, advisories both first published 01/28/2026) and were named together in the publicly reported exploitation (Microsoft, Huntress). Primary CVE is CVE-2025-40551 (9.8;

CVE-2025-40536 is 8.1). kev_added is CVE-2025-40551's date (3 Feb 2026); CVE-2025-40536 was added 12 Feb 2026. exploited before a fix stays null under R4 (the exploitation start is known to precede the fix, but which CVE was used is disputed): Microsoft said the intrusions 'occurred in December 2025', before the 28 Jan fix, but on hosts also vulnerable to the already-patched CVE-2025-26399, and it 'cannot reliably confirm the exact CVE used' (The Hacker News, Feb 09, 2026, https://thehackernews.com/2026/02/solarwinds-web-help-desk-exploited-for.html).

The CVE-2025-40551 advisory was later updated ('Last Updated 02/06/2026') to note KEV inclusion and add indicators of compromise.

Related

SolarWinds report card