APT RCE via hard link reuse
Written by anthropic/claude-haiku-5.5 from the sources below. Verify against them.
- Exploited
- No known exploitation
- Fix
- Fixed in 1.2.36, 1.4.12, 1.6.19, 1.8.2.4, 2.0.12, and 10 more
- Who is exposed
- Specific setups only
Do first: Upgrade to a fixed version: 1.2.36, 1.4.12, 1.6.19, 1.8.2.4, 2.0.12, or one of 10 more.
- Exploitation0/40No signal
- Exposure12/25Specific setups only, reachable over the network without a login
- Reach10/20Shipped in major Linux distributions
- Severity8.7/10CVSS 7.7, total technical impact per CISA
- No patch0/5No signal
What would change the score
- Would score about 81 if added to CISA KEV
- Would score about 76 if CISA's SSVC rates exploitation active
CVE-2026-109518 is not in CISA's Known Exploited Vulnerabilities (KEV) catalog. No public exploit code is tracked. It is rated CVSS 7.7 (high) and affects APT; fixed in 1.2.36, 1.4.12, 1.6.19 and 12 more.
- Last modified
- Where the record stands: published, rejected by its publisher, or superseded by another id.What do these mean? →
- Published
- Whether CISA lists it in its Known Exploited Vulnerabilities catalog: proof that attackers are using it.What do these mean? →
- Not listed in CISA KEV
- A 0-100 score for how much a CVE matters across the industry: exploitation, exposure, how widely the software is used, severity and whether a fix exists.What do these mean? →
- 31/100 · provisional
- How many real-world setups can hit the bug, from the vendor's advisory and CISA data. It does not know your setup.What do these mean? →
- Specific setups only
- Fix
- Fixed in 1.2.36, 1.4.12, 1.6.19, 1.8.2.4, 2.0.12, and 10 more
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- 1 proof of concept on GitHub
- Exploitation: none
- Automatable: no
- Technical impact: total
Summary
APT, the package manager on Debian, Ubuntu, and their derivatives, can be tricked into installing an attacker-controlled, unverified package, giving the attacker remote code execution with root privileges. An attacker on the network path, such as through a malicious mirror or proxy that manipulates HTTP traffic, can reach it remotely without logging in, but it requires a user to run a package install and the client to have download retries enabled.
Read the original description
On Debian, Ubuntu, and derivative Linux distributions, an on-path attacker who can manipulate the HTTP traffic (including a malicious mirror or proxy) between an APT client and an archive server triggered by a package install can trick the client into installing an attacker-controlled unverified package and achieve remote code execution with root privileges. The vulnerability is caused by the reuse of hard links and requires the client to follow redirects and retry the download of package files. It requires the client to have a non-zero Acquire::Retries configuration setting; the value 3 is the default starting with Debian 12 (bookworm) and Ubuntu 22.04 LTS (Jammy Jellyfish), so older releases are unaffected in a default configuration
What to do
Upgrade to a fixed version: 1.2.36, 1.4.12, 1.6.19, 1.8.2.4, 2.0.12, or one of 10 more.
Timeline
- CVE published
- First seen by cve.now
- CISA SSVC assessment
Exploitation: none · Automatable: no · Technical impact: total
1 day - Record last updated
Affected versions
- apt
fixed in 1.2.36; From 1.4.0 · fixed in 1.4.12; From 1.6.0 · fixed in 1.6.19; From 1.8.0 · fixed in 1.8.2.4; From 1.8.3 · through 1.8.5; From 2.0.0 · fixed in 2.0.12; From 2.2.0 · fixed in 2.2.5; From 2.4.0 · fixed in 2.4.15; From 2.6.0 · fixed in 2.6.2; From 2.8.0 · fixed in 2.8.4; From 3.0.0 · fixed in 3.0.4; From 3.2.0 · fixed in 3.2.1; From 3.3.0 · fixed in 3.3.6
- apt
fixed in 1.0.1ubuntu2.24+esm4; From 1.2.0 · fixed in 1.2.36+esm1; From 1.6.0 · fixed in 1.6.19+esm1; From 2.0.0 · fixed in 2.0.12+esm1; From 2.4.0 · fixed in 2.4.15ubuntu0.1; From 2.8.0 · fixed in 2.8.4ubuntu0.1; From 3.2.0 · fixed in 3.2.1ubuntu0.1; From 3.3.0 · fixed in 3.3.3ubuntu0.1
Evidence 5
- Advisory
- Advisory
- Exploit
- Link
- Link
Corrections
None so far.
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Questions about CVE-2026-109518
Is CVE-2026-109518 being exploited?
It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.Source: cve.now feed data
What does this mean?
A man-in-the-middle attacker who sits between APT and its package source can replace a package after APT has verified it. The replaced package then runs arbitrary code with root privileges.Source: lists.debian.org
Which versions are affected by CVE-2026-109518?
apt: before 1.2.36; from 1.4.0 before 1.4.12; from 1.6.0 before 1.6.19; from 1.8.0 before 1.8.2.4; from 1.8.3 through 1.8.5; from 2.0.0 before 2.0.12; from 2.2.0 before 2.2.5; from 2.4.0 before 2.4.15; from 2.6.0 before 2.6.2; from 2.8.0 before 2.8.4; from 3.0.0 before 3.0.4; from 3.2.0 before 3.2.1; from 3.3.0 before 3.3.6. apt: before 1.0.1ubuntu2.24+esm4; from 1.2.0 before 1.2.36+esm1; from 1.6.0 before 1.6.19+esm1; from 2.0.0 before 2.0.12+esm1; from 2.4.0 before 2.4.15ubuntu0.1; from 2.8.0 before 2.8.4ubuntu0.1; from 3.2.0 before 3.2.1ubuntu0.1; from 3.3.0 before 3.3.3ubuntu0.1.Source: cve.now feed data
Am I affected, and how do I check?
The advisory lists Debian APT and Ubuntu APT, each with version ranges that differ by release line. To check a system, run `apt --version` and compare the result against the fixed versions for its distribution.Source: lists.debian.org
How do I fix CVE-2026-109518?
Upgrade APT to the fixed version for your distribution. For Debian stable (trixie), that is 3.0.4.Source: lists.debian.org