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    CVE-2026-77639

    Tor before 0.4.9.9 was prone to a compression bomb bypass where an attacker could concatenate many gzip or zlib sub-streams, each just under the per-stream detection threshold, to avoid the compression bomb check entirely. This is TROVE-2026-022.

    Published:Aug 20, 2026
    Last Modified:Aug 21, 2026
    EPS:Aug 20, 2026
    EPSS Score:0.00246
    CVSS Score:5.3

    Affected Products

    Vendor
    Torproject
    Product
    Tor

    Exploits

    No exploit reference

    Common Weakness Enumeration

    CWE-420 Unprotected Alternate Channel

    Common Attack Pattern Enumeration and Classification (CAPEC)

    No CAPEC recorded yet

    Related CVEs

    CVE-2026-87724 (CVSS 6.5) — Tor before 0.4.9.12 interprets the CC_RESPONSE extension even when CC_REQUEST was not sent, which allows remot…
    CVE-2026-77642 (CVSS 7.5) — tor before 0.4.9.9 was prone to an out-of-bounds write when parsing a consensus or detached signature with un…
    CVE-2026-77641 (CVSS 6.5) — tor before 0.4.9.9 was prone to a NULL write after free when sending a CONFLUX_SWITCH cell fails. The return v…
    CVE-2026-77640 (CVSS 3.7) — tor before 0.4.9.9 was prone to an infinite loop when decompressing a truncated zlib/gzip stream with done=1.…
    CVE-2026-77638 (CVSS 8.9) — Tor before 0.4.9.11 is prone to a race condition where in just the right circumstances a rendezvous point coul…
    CVE-2026-77587 (CVSS 5.9) — Tor before 0.4.9.11 is prone to a use-after-free (and potential double free) of a conflux object when a recove…
    CVE-2026-77584 (CVSS 7) — Tor before 0.4.9.10 did not reject a CONFLUX_LINK cell that arrives on a circuit which already has attached st…
    CVE-2026-44603 (CVSS 3.7) — Tor before 0.4.9.7 has an out-of-bounds read by one byte via a malformed BEGIN cell, aka TROVE-2026-007.…
    CVE-2026-44602 (CVSS 3.7) — Tor before 0.4.9.7 has a NULL pointer dereference when a CERT cell is received out of order, aka TROVE-2026-00…
    CVE-2026-44601 (CVSS 3.7) — Tor before 0.4.9.7, when circuit queue memory pressure exists, can experience a client crash because of a doub…

    Common Vulnerability Scoring System

    Attack Vector
    Network
    Adjacent
    Local
    Physical
    Privileges Required
    None
    Low
    High
    User Interaction
    None
    Required
    Scope
    Unchanged
    Changed
    Confidentiality
    None
    Low
    High
    Integrity
    None
    Low
    High
    Availability
    None
    Low
    High