WordPress Core: attackers can run their own code
OFFICIAL NAME: WordPress WordPress Core Time-of-check Time-of-use (TOCTOU) Race Condition Vulnerability
WHAT IT IS · WEBSITE OR ONLINE STOREIt runs public websites, online stores or the software behind them.
DO THIS FIRSTAsk whoever runs your website or store to update it. Not sure if you use it? Send this page to your IT provider or security lead and ask.
TECHNICAL SUMMARY WordPress WordPress Core contains a time-of-check time-of-use (TOCTOU) race condition vulnerability that could allow unauthenticated attackers to execute code on the server during the upgrade window. This is due to predictable, web-accessible staging paths used during full-package core upgrades.
WHY THIS VERDICT Attacks are confirmed. The vulnerability is 11 days old, so many systems are likely still unpatched.
WHY IT RANKS HERE Exploitation is confirmed by an authoritative source. The confirmation is 8 days old.
- HIGHEST CONFIRMED RUNG
- EXPLOITED
- CISA KEV
- LISTED
- EXPLOIT CODE
- PROOF OF CONCEPT
How far has it climbed?
01 TALK
■ CONFIRMEDNEWEST EVIDENCE · 4 INDEPENDENT SOURCESCVE-2026-119977 discussed publicly (CIRCL sighting). CVE-2026-119977 discussed publicly (CIRCL sighting).
- SRC: CIRCL Vulnerability-Lookup sightings: CVE-2026-119977 discussed publicly (CIRCL sighting) · NOV 10
- SRC: Security Affairs: U.S. CISA adds WordPress flaw to its Known Exploited Vulnerabilities catalog · NOV 4
- SRC: The Hacker News: CISA Confirms Hackers Exploiting WordPress Core Flaw During Software Upgrades · NOV 3
02 EXPOSED
□ NOT TRACKED YETNO SOURCE FOR THIS STEP YETWe have no source that counts exposed systems yet. Internet scan data needs a partnership we do not have. No evidence here does not mean nothing is exposed.
03 TRIED
■ CONFIRMEDNEWEST EVIDENCE · 3 INDEPENDENT SOURCESAttacks that worked are confirmed (step 4), so attempts count as confirmed too.
- SRC: CIRCL Vulnerability-Lookup sightings: Exploitation of CVE-2026-119977 reported (CIRCL sighting) · NOV 8
- SRC: CISA Known Exploited Vulnerabilities: WordPress WordPress Core Time-of-check Time-of-use (TOCTOU) Race Condition Vulnerability · NOV 2
- SRC: CVE List V5 and CISA Vulnrichment: CISA Vulnrichment marks CVE-2026-119977 as actively exploited · OCT 30
04 EXPLOITED
■ CONFIRMEDNEWEST EVIDENCE · 3 INDEPENDENT SOURCESExploitation of CVE-2026-119977 reported (CIRCL sighting). Exploitation of CVE-2026-119977 reported (CIRCL sighting).
- SRC: CIRCL Vulnerability-Lookup sightings: Exploitation of CVE-2026-119977 reported (CIRCL sighting) · NOV 8
- SRC: CISA Known Exploited Vulnerabilities: WordPress WordPress Core Time-of-check Time-of-use (TOCTOU) Race Condition Vulnerability · NOV 2
- SRC: CVE List V5 and CISA Vulnrichment: CISA Vulnrichment marks CVE-2026-119977 as actively exploited · OCT 30
05 DAMAGE
□ NOT TRACKED YETNO SOURCE FOR THIS STEP YETBreach notices and filings rarely name the flaw that was used, so we cannot link them to this event yet. No evidence here does not mean no harm.
When each thing happened
- DISCLOSED
- EXPLOIT CODE PUBLIC
- FIRST ATTACK REPORT
- CISA KEV LISTING
- US FEDERAL DEADLINE
THE FIX
CISA's instruction: apply the vendor's fix, or stop using the product if no fix exists. The deadline CISA set for US federal agencies, Nov 6, 2026, has passed. It is a US government deadline; use it as a guide.
Questions to ask this week
- Do we run WordPress Core? If yes, is it patched or cut off from the internet?
- Who owns fixing it, and by what date?
- Have we checked for signs of attack since the first report, not just since the patch?
How it unfolded
- Attack activity. OCT 30, 2026CISA Vulnrichment marks CVE-2026-119977 as actively exploited
- Attack activity. NOV 2, 2026WordPress WordPress Core Time-of-check Time-of-use (TOCTOU) Race Condition Vulnerability
- NOV 3, 2026CVE-2026-119977 discussed publicly (CIRCL sighting) (96 reports, latest NOV 10)
- NOV 3, 2026WordPress security advisory (AV26-1117)
- NOV 3, 20261 public GitHub repository claims a proof of concept for CVE-2026-119977
- NOV 3, 2026CISA Confirms Hackers Exploiting WordPress Core Flaw During Software Upgrades
- Attack activity. NOV 3, 2026Exploitation of CVE-2026-119977 reported (CIRCL sighting) (2 reports, latest NOV 8)
- NOV 4, 2026U.S. CISA adds WordPress flaw to its Known Exploited Vulnerabilities catalog
- NOV 4, 2026Public proof of concept for CVE-2026-119977 (CIRCL sighting) (6 reports, latest NOV 10)
SOURCES
- [1] CIRCL Vulnerability-Lookup sightings: CVE-2026-119977 discussed publicly (CIRCL sighting), NOV 10
- [2] CIRCL Vulnerability-Lookup sightings: Public proof of concept for CVE-2026-119977 (CIRCL sighting), NOV 10
- [3] CIRCL Vulnerability-Lookup sightings: Exploitation of CVE-2026-119977 reported (CIRCL sighting), NOV 8
- [4] Security Affairs: U.S. CISA adds WordPress flaw to its Known Exploited Vulnerabilities catalog, NOV 4
- [5] The Hacker News: CISA Confirms Hackers Exploiting WordPress Core Flaw During Software Upgrades, NOV 3
- [6] PoC-in-GitHub: 1 public GitHub repository claims a proof of concept for CVE-2026-119977, NOV 3
- [7] Canadian Centre for Cyber Security: WordPress security advisory (AV26-1117), NOV 3
- [8] CISA Known Exploited Vulnerabilities: WordPress WordPress Core Time-of-check Time-of-use (TOCTOU) Race Condition Vulnerability, NOV 2
- [9] CVE List V5 and CISA Vulnrichment: CISA Vulnrichment marks CVE-2026-119977 as actively exploited, OCT 30
- [10] CIRCL Vulnerability-Lookup sightings: 101 more reports