rabbitmq-c: amqp_decode_bytes size_t integer overflow bypasses bounds check on 32-bit (OOB read)
Affects rabbitmq-c before 0.17.0 on 32-bit platforms, where decoding a BYTES/UTF8 field from an AMQP frame received from the wire can read out of bounds. Fixed in 0.17.0.
Written by anthropic/claude-haiku-5.5 from the sources below. Verify against them.
- Exploited
- Proof of concept public, per CISA
- Fix
- Fixed in 0.17.0
- Who is exposed
- Not reported
Do first: Upgrade to a fixed version: 0.17.0.
- Last modified
- Whether it needs action now or is a reference record, by fixed rules, with why. Last checked is when cve.now last re-read it.What do these mean? →
- Reference
- Last checked
- 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? →
- 39/100 · 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? →
- Unclear
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
- Exploitation: poc
- Automatable: no
- Technical impact: partial
Summary
The rabbitmq-c AMQP client library, used by C programs to talk to RabbitMQ, has a flaw in how it decodes byte fields on 32-bit systems that lets an attacker read up to about 4 GB of process memory outside the intended buffer, which can leak information or crash the client. An attacker can trigger it remotely over the network without logging in, though exploiting it requires a high-complexity setup, and the bug is not exploitable on 64-bit systems.
Read the original description
rabbitmq-c is a C-language AMQP client library for RabbitMQ. Prior to version 0.17.0, the bounds check (*offset = o + len) <= encoded.len overflows when o + len > SIZE_MAX on 32-bit systems. len is a uint32_t read from the AMQP wire as a BYTES/UTF8 field length. The overflow wraps the check to a small value that passes, producing a decoded amqp_bytes_t with a multi-GB .len pointing into a small frame buffer. This results in an out-of-bounds read of up to ~4GB of process memory on 32-bit systems (ARM, MIPS, x86 ILP32, embedded IoT AMQP clients). Enabling information disclosure or denial of service. Not exploitable on 64-bit systems where size_t is 64-bit. This issue has been patched in version 0.17.0.
cve.now Index
- Exploitation15/40CISA rates a proof of concept as public
- Exposure17/25No login or user action needed, reachable over the network without a login · Unknown: Advisories don't say whether default setups are affected
- Reach?/20Unknown. No tracked technology or package matched
- Severity7.4/10CVSS 7.4
- No patch0/5No signal
What would change the score
- Would score about 69 if added to CISA KEV
- Would score about 64 if CISA's SSVC rates exploitation active
- Would score about 44 if advisories confirm default setups are exposed
What to do
Upgrade to a fixed version: 0.17.0.
Check your systems with an agent
Paste this into a coding or ops agent. It checks your systems read-only and reports a table per asset.
Check whether my systems are affected by CVE-2026-59986 (rabbitmq-c: amqp_decode_bytes size_t integer overflow bypasses bounds check on 32-bit (OOB read)), using the cve.now data below. Rules: work read-only. Do not run exploit code, proof-of-concept scripts or scanners that send attack payloads, and do not change any configuration, package, image or deployment. Report findings only. What cve.now has for CVE-2026-59986 (entry last updated 2026-11-10): Affected: - alanxz rabbitmq-c: fixed in 0.17.0 Fixed versions: 0.17.0. Conditions (all must be true for the bug to be hit): - Runs on a 32-bit platform, where size_t is 32-bit (source: https://github.com/alanxz/rabbitmq-c/security/advisories/GHSA-jgjf-7fwf-f3c7) - Client decodes a BYTES/UTF8 field from an AMQP frame received from the wire (source: https://github.com/alanxz/rabbitmq-c/security/advisories/GHSA-jgjf-7fwf-f3c7) Setup: unknown whether the bug needs a non-default feature or setting. Check the advisory. Attacker needs: network access, no login, no user action. CISA KEV: CVE-2026-59986 is not listed as of cve.now's last read. This KEV status is for CVE-2026-59986 only. If you also check another CVE, look up its own KEV status; never assume it from this one. How to check: - Installed software: check what is actually running, not what a repo declares. Read the version from each host, container image and Kubernetes node (the binary's version output, the OS package database, image layers), and check whether the conditions above hold there. Distribution packages may carry a backported fix under an older version number; confirm against the distribution's own advisory. Verify against the linked advisories before concluding, and cite the date you read each one: - https://github.com/alanxz/rabbitmq-c/security/advisories/GHSA-jgjf-7fwf-f3c7 - https://github.com/alanxz/rabbitmq-c/pull/888 - https://github.com/alanxz/rabbitmq-c/releases/tag/v0.17.0 Do not conclude an asset is unaffected unless you checked it and the evidence covers both its version and the conditions above. If you could not check something, mark it unknown and say what is missing. Report a table with one row per asset and these columns: Asset | Version or build | Status (affected, fixed, not applicable, unknown) | Compensating controls | Exposure (internet-facing, internal, none) | Evidence | Next action. Entry: https://cve.now/CVE-2026-59986 For follow-up questions, use the cve.now MCP server at https://mcp.cve.now/mcp (no authentication), for example get_vulnerability with id CVE-2026-59986.
Timeline
- CVE published
- First seen by cve.now
- CISA SSVC assessment
Exploitation: poc · Automatable: no · Technical impact: partial
- Record last updated
Affected versions
- alanxz rabbitmq-c
fixed in 0.17.0
Evidence 5
Vendor advisory · 1
Establishes: Affected and fixed versions.
- Advisory
CVE record · 2
Establishes: The identifier and description.
- Record
- Record
Other links · 2
- Repository
- Repository
Corrections
None so far.
Something wrong on this page? Report an error. Every fix is listed here.
Questions about CVE-2026-59986
Is CVE-2026-59986 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. CISA's SSVC assessment notes a proof of concept exists. No public exploit code is tracked.Source: cve.now feed data
What does this mean?
amqp_decode_bytes checks bounds by adding an offset and a length, but on 32-bit systems that sum can overflow size_t and wrap around, so the check passes when it should fail. The result is an out-of-bounds read of up to about 4 GB of process memory, which can disclose information or crash the process.Source: github.com
Which versions are affected by CVE-2026-59986?
rabbitmq-c: before 0.17.0.Source: cve.now feed data
Am I affected, and how do I check?
Versions of rabbitmq-c before 0.17.0 are affected. The bug only matters on 32-bit platforms, where size_t is 32 bits, and in code that decodes BYTES or UTF8 fields from AMQP frames received over the wire. To check, look at the rabbitmq-c version your build or package manager reports and confirm whether the target platform is 32-bit.Source: github.com
How do I fix CVE-2026-59986?
Upgrade rabbitmq-c to version 0.17.0 or later.Source: github.com