Unrated

Replay attack in Apache Tomcat EncryptionInterceptor

IdentifiersCVE-2026-55955CWE-287

CVE-2026-55955 is an improper authentication vulnerability in Apache Tomcat's cluster component. The flaw affects the EncryptionInterceptor (also referred to in the provided context as EncryptInterceptor), which was not adequately protected against replay attacks. As a result, previously captured valid protected cluster traffic can be replayed to a Tomcat node and accepted when it should have been rejected. The issue affects Apache Tomcat 11.0.0-M1 through 11.0.22, 10.1.0-M1 through 10.1.55, 8.5.38 through 8.5.100, and 7.0.100 through 7.0.109. For the 9.0.x branch, the provided content is inconsistent: one location states 9.0.13 through 9.0.18, while the fact extraction indicates 9.0.13 through 9.0.118; the fixed version listed is 9.0.119.

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ANALYST BRIEF

Impact, mitigation & remediation

What it means. What to do now. Patch path, mitigations, and the assume-compromise checklist.

Impact

What an attacker gets, and what they’ve been doing with it.

Successful exploitation allows an attacker to perform a replay attack against Tomcat clustered communications protected by the EncryptionInterceptor. This can undermine the authenticity guarantees expected for cluster messages by causing a node to accept duplicated previously valid traffic. Based on the provided information, the primary impact is bypass of intended authentication/integrity protections for clustered message exchange; more specific downstream impacts are not available in the supplied content.

Mitigation

If you can’t patch tonight, do this now.

If immediate upgrade is not possible, reduce exposure of the Tomcat cluster component by restricting cluster network access to trusted hosts and isolated management/internal networks only, and disable or avoid use of the EncryptionInterceptor/cluster functionality where operationally feasible until patched. No vendor-specific mitigation beyond upgrading is provided in the supplied content.

Remediation

Patch, then assume compromise.

Upgrade Apache Tomcat to a fixed version. The provided content identifies fixes in 11.0.23, 10.1.56, and 9.0.119. The content does not provide fixed versions for the 8.5.x and 7.0.x branches; that information is currently not available in the supplied material. Because the provided content contains an inconsistency for affected 9.0.x versions, operators should verify the exact affected range against the official Apache advisory/CVE record before patch planning.

PUBLIC EXPLOITS

Exploits

No public exploits tracked yet. Mallory keeps watching.

VALID 0 / 0 TOTALView more in app

No public exploit code observed for this vulnerability.

ACTIVITY FEED

Recent activity

9 sources tracked across advisories and community write-ups. News coverage will land here when it surfaces.

9 SOURCESView more in app

No news coverage yet. Advisories and community discussion only.

What this page doesn’t show

The version that knows your environment.

This page is what’s public. Mallory adds the parts that aren’t: which of your assets are affected, which adversaries are exploiting it right now, which detections to deploy, and what to do tonight.

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Exposure mapping

Query your assets running an affected version, and investigate the blast radius.

Threat actor evidence

Every observed campaign linking this CVE to a named adversary.

Associated malware

Malware families riding this exploit, with evidence and IOCs.

Detection signatures

YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.

Vendor-by-vendor mapping

Cross-references every affected SKU, including bundled OEM variants.

Social activity9

Community discussion across Reddit, Mastodon, and other social sources.

EXTERNAL REFERENCES

MITRE CVE

cve.org · CVE-2026-55955

NVD

nvd.nist.gov/vuln/detail/CVE-2026-55955

MITRE CWE · CWE-287

cwe.mitre.org