CVE-2026-8933

Published Jul 21, 2026

Last updated 3 months ago

CVSS high 7.8
Ubuntu

Overview

AI description

Automated description summarized from trusted sources.

CVE-2026-8933 is a local privilege escalation vulnerability found in `snap-confine`, a critical component of Canonical's `snapd` that establishes secure execution environments for snap applications. This flaw specifically impacts systems where `snap-confine` is configured with `set-capabilities` rather than the traditional `set-uid-root` mode. An unprivileged local attacker can exploit this vulnerability to bypass the intended sandbox initialization and execute arbitrary code with root privileges. The vulnerability stems from improper handling of privilege boundaries and a race condition during the sandbox setup process. When `snap-confine` creates temporary directories and files, they are initially owned by the unprivileged user. This creates a narrow window during which an attacker can manipulate these files, for instance, by mounting a FUSE filesystem and creating symbolic links to redirect file operations to sensitive system locations, ultimately leading to root access. Default installations of Ubuntu Desktop 24.04, 25.10, and 26.04 are among the affected systems.

Description
A local privilege escalation vulnerability exists in snap-confine, a set-capabilities core component used internally by Canonical snapd to construct the secure execution environment for snap applications. This vulnerability uniquely affects versions of snap-confine configured with set-capabilities (rather than standard set-uid-root installations). Due to a flaw in how privilege boundaries or security sandboxes are initialized when the binary runs under limited ambient capabilities, a local, unprivileged attacker can exploit this behavior to bypass intended restrictions and execute arbitrary code. Successful exploitation allows the local user to elevate their privileges to full root authority.
Source
security@ubuntu.com
NVD status
Awaiting Analysis

Risk scores

CVSS 3.1

Type
Secondary
Base score
7.8
Impact score
5.9
Exploitability score
1.8
Vector string
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Severity
HIGH

Weaknesses

security@ubuntu.com
CWE-250

Social media

Hype score
Not currently trending

  1. lpe-toolkit has been updated with new LPE exploits! New exploits added: - RefluXFS CVE-2026-64600 - CrackArmor CVE-2026-23268 - skb_shift CVE-2026-43503 - GRO Flag Loss CVE-2026-43503 - snap-confine CVE-2026-8933 https://t.co/Uafh1WjbqV

    @portbuster1337

    23 Sept 2026

    6594 Impressions

    19 Retweets

    94 Likes

    53 Bookmarks

    0 Replies

    0 Quotes

  2. 🐧 𝗔𝗟𝗘𝗥𝗧𝗔 𝗟𝗜𝗡𝗨𝗫: 2 fallas críticas de escalamiento de privilegios 🔹 CVE-2026-8933 → Ubuntu Desktop 🔹 CVE-2026-64600 "RefluXFS" → RHEL, CentOS, Rocky, AlmaLinux, Fedora, Amazon Linux Más info 👇👇 https://t.co/9PL0Ewg3GT #Ciberse

    @LeonelM41262107

    24 Jul 2026

    131 Impressions

    2 Retweets

    1 Like

    0 Bookmarks

    0 Replies

    0 Quotes

  3. CVE-2026-8933: a snap-confine flaw gives any local user root on default Ubuntu Desktop 24.04, 25.10 and 26.04. Ironically introduced by a 2025 least-privilege hardening change. Patch shipped Jul 21. https://t.co/4ElHRDxS2Y #cybersecurity #Linux

    @JNitterauer

    23 Jul 2026

    98 Impressions

    0 Retweets

    0 Likes

    0 Bookmarks

    0 Replies

    0 Quotes

  4. A critical flaw in Ubuntu's snap-confine component, CVE-2026-8933, allows local users to gain root access on default installations of Ubuntu Desktop 24.04, 25.10, and 26.04. This vulnerability stems from a race condition introduced during a security hardening change in July 2025.

    @dailytechonx

    23 Jul 2026

    113 Impressions

    1 Retweet

    1 Like

    0 Bookmarks

    0 Replies

    0 Quotes

  5. 🔒💥 ¡ALERTA DE SEGURIDAD EN UBUNTU! Canonical revela 3 vulnerabilidades críticas en snapd que afectan versiones desde Ubuntu 16.04 LTS. CVE-2026-8933 permite escalado de privilegios. CVE-2026-15226 posibilita escape de confinación. CVE-2024-5300 expone contraseñas

    @DiarioBitcoin

    23 Jul 2026

    932 Impressions

    0 Retweets

    1 Like

    0 Bookmarks

    1 Reply

    0 Quotes

  6. 🚨 High-Severity Ubuntu Alert Qualys TRU has disclosed CVE-2026-8933, a local privilege escalation in snap-confine that grants full root access to any unprivileged local user on default Ubuntu Desktop installations. The flaw arises from race conditions in temporary directory h

    @FriendOfTheInst

    22 Jul 2026

    112 Impressions

    0 Retweets

    1 Like

    0 Bookmarks

    0 Replies

    0 Quotes

Related CVEs

  1. Issue summary: The DTLS retransmission logic does not correctly handle a handshake message write that is suspended part-way through. The retransmitted message can be read past the message buffer and the retransmission overwrites the internal state the suspended write needs to resume correctly. Impact summary: The retransmitted message can disclose a heap memory to the peer as plaintext handshake data or cause a crash and a Denial of Service when the read reaches an unmapped memory region. CWE: CWE-125: Out-of-bounds Read Description: DTLS handshake messages can be written out in multiple fragments, and a write can suspend mid-message (returning WANT_WRITE) if the underlying transport temporarily cannot accept more data. While such a write is suspended, the DTLS retransmission timer may independently fire and ask the retransmission logic to resend an earlier, already-acknowledged-as-sent message from its retransmit queue. The retransmission logic reused the same internal buffer and position tracking as the message that was still being written, without resetting the position back to the start of the message being retransmitted. As a result the retransmission was read starting from wherever the suspended write had left off, producing a mislabelled message whose body was leftover bytes from the other, larger message still in flight - content that was never meant to be sent at that point, and which could run past the end of the allocated buffer. Separately, even when the retransmission is positioned correctly, allowing it to run to completion while another write is suspended overwrites the same shared bookkeeping that the suspended write depends on to resume. When the application later resumes the suspended write (via a subsequent SSL_read(), SSL_write(), SSL_accept(), or SSL_connect() call), it finds that bookkeeping in a state inconsistent with the message and aborts the process in a debugging build. The fix resets the retransmission's read position to the start of the message before resending, and skips retransmission entirely whenever a handshake write is still suspended, deferring to the next call that resumes it instead. FIPS impact: no The affected code is outside the FIPS module boundary.•CVE-2026-84782
  2. ZoneMinder versions 1.37.0 before 1.38.0 contain a path traversal vulnerability in the files view that allows authenticated users to read arbitrary files. The path parameter is not properly validated before being passed to output_file, enabling attackers with Events view permission to access sensitive files like configuration files containing database credentials.•CVE-2024-58386
  3. WordPress Core Remote File Inclusion Vulnerability•CVE-2026-87902
  4. Google Chromium V8 Type Confusion Vulnerability•CVE-2026-85046
  5. In the Linux kernel, the following vulnerability has been resolved: net: gro: properly validate BIG TCP aggregation criteria When GRO attempts to aggregate packets beyond GRO_LEGACY_MAX_SIZE (64KB), BIG TCP should only be permitted for plain IPv4 TCP and plain IPv6 TCP (with sufficient MAC header room to insert the temporary HBH jumbo header). However, commit b1a78b9b9886 ("net: add support for ipv4 big tcp") loosened the check in skb_gro_receive(), leading to several issues: 1. skb_gro_receive() checked skb_headroom(p) instead of the actual space before the MAC header (p->mac_header). Because skb_headroom(p) includes mac_len, crafted frames (e.g. injected via AF_PACKET) can pass the check with p->mac_header < 8 bytes. When ipv6_gro_complete() inserts the temporary HBH jumbo header, the memmove() starts before skb->head, causing an out-of-bounds write and wrapping skb->mac_header. 2. It allowed non-IP protocols such as software VLAN (ETH_P_8021Q / ETH_P_8021AD) to aggregate beyond 64KB because p->protocol != ETH_P_IPV6 was true. 3. It checked p->encapsulation instead of NAPI_GRO_CB(skb)->encap_mark, allowing encapsulated flows (e.g. SIT / IPv6-in-IPv4) to aggregate beyond 64KB. Fix skb_gro_receive() to strictly enforce: - NAPI_GRO_CB(skb)->proto == IPPROTO_TCP - Not encapsulated (!NAPI_GRO_CB(skb)->encap_mark && !p->encapsulation) - Protocol must be either ETH_P_IP or ETH_P_IPV6 - If ETH_P_IPV6, p->mac_header must be at least sizeof(struct hop_jumbo_hdr) Returning -E2BIG from skb_gro_receive() ensures that packets which cannot become BIG TCP are cleanly flushed at <= 64KB and delivered intact without dropping. This issue does not exist in mainline (7.0+) because the subsystem was rewritten in commit 81be30c1f5f2 ("net/ipv6: Drop HBH for BIG TCP on RX side"), making this fix relevant only for older stable branches like 6.18.y.•CVE-2026-80725

References

Sources include official advisories and independent security research.