CVE-2026-29181

ADVISORY - github

Summary

multi-value baggage: header extraction parses each header field-value independently and aggregates members across values. this allows an attacker to amplify cpu and allocations by sending many baggage: header lines, even when each individual value is within the 8192-byte per-value parse limit.

severity

HIGH (availability / remote request amplification)

relevant links

repository: https://github.com/open-telemetry/opentelemetry-go
pinned callsite: https://github.com/open-telemetry/opentelemetry-go/blob/1ee4a4126dbdd1bc79e9fae072fa488beffac52a/propagation/baggage.go#L58

vulnerability details

pins: open-telemetry/opentelemetry-go@1ee4a4126dbdd1bc79e9fae072fa488beffac52a as-of: 2026-02-04 policy: direct (no program scope provided)

callsite: propagation/baggage.go:58 (extractMultiBaggage) attacker control: inbound HTTP request headers (many baggage field-values) → propagation.HeaderCarrier.Values("baggage") → repeated baggage.Parse + member aggregation

root cause

extractMultiBaggage iterates over all baggage header field-values and parses each one independently, then appends members into a shared slice. the 8192-byte parsing cap applies per header value, but the multi-value path repeats that work once per header line (bounded only by the server/proxy header byte limit).

impact

in a default net/http configuration (max header bytes 1mb), a single request with many baggage: header field-values can cause large per-request allocations and increased latency.

example from the attached PoC harness (darwin/arm64; 80 values; 40 requests):

canonical: per_req_alloc_bytes=10315458 and p95_ms=7
control: per_req_alloc_bytes=133429 and p95_ms=0

proof of concept

canonical:

mkdir -p poc
unzip poc.zip -d poc
cd poc
make test

output (excerpt):

[CALLSITE_HIT]: propagation/baggage.go:58 extractMultiBaggage
[PROOF_MARKER]: baggage_multi_value_amplification p95_ms=7 per_req_alloc_bytes=10315458 per_req_allocs=16165

control:

cd poc
make control

control output (excerpt):

[NC_MARKER]: baggage_single_value_baseline p95_ms=0 per_req_alloc_bytes=133429 per_req_allocs=480

expected: multiple baggage header field-values should be semantically equivalent to a single comma-joined baggage value and should not multiply parsing/alloc work within the effective header byte budget. actual: multiple baggage header field-values trigger repeated parsing and member aggregation, causing high per-request allocations and increased latency even when each individual value is within 8192 bytes.

fix recommendation

avoid repeated parsing across multi-values by enforcing a global budget and/or normalizing multi-values into a single value before parsing. one mitigation approach is to treat multi-values as a single comma-joined string and cap total parsed bytes (for example 8192 bytes total).

fix accepted when: under the default PoC harness settings, canonical stays within 2x of control for per_req_alloc_bytes and per_req_allocs, and p95_ms stays below 2ms.

poc.zip PR_DESCRIPTION.md

EPSS Score⁠: 0.00572 (0.445)

Common Weakness Enumeration (CWE)

ADVISORY - nist

CWE-770⁠

Allocation of Resources Without Limits or Throttling

ADVISORY - github

CWE-400⁠

Uncontrolled Resource Consumption

CWE-770⁠

Allocation of Resources Without Limits or Throttling

Impacted images

Advisories

GitHub

CREATED

4 months ago

UPDATED

4 months ago

ADVISORY IDGHSA-mh2q-q3fh-2475⁠

EXPLOITABILITY SCORE

3.9

EXPLOITS FOUND

COMMON WEAKNESS ENUMERATION (CWE)

CWE-400⁠CWE-770⁠

CVSS SCORE

7.5high

Package	Type	OS Name	OS Version	Affected Ranges	Fix Versions
go.opentelemetry.io/otel	golang	-	-	>=1.36.0,<=1.40.0	1.41.0

CVSS:3 Severity and metrics

The CVSS metrics represent different qualitative aspects of a vulnerability that impact the overall score, as defined by the CVSS Specification⁠.

The vulnerable component is bound to the network stack, but the attack is limited at the protocol level to a logically adjacent topology. This can mean an attack must be launched from the same shared physical (e.g., Bluetooth or IEEE 802.11) or logical (e.g., local IP subnet) network, or from within a secure or otherwise limited administrative domain (e.g., MPLS, secure VPN to an administrative network zone). One example of an Adjacent attack would be an ARP (IPv4) or neighbor discovery (IPv6) flood leading to a denial of service on the local LAN segment (e.g., CVE-2013-6014).

Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success when attacking the vulnerable component.

The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files of the vulnerable system to carry out an attack.

The vulnerable system can be exploited without interaction from any user.

An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.

There is no loss of confidentiality.

There is no loss of trust or accuracy within the impacted component.

There is a total loss of availability, resulting in the attacker being able to fully deny access to resources in the impacted component; this loss is either sustained (while the attacker continues to deliver the attack) or persistent (the condition persists even after the attack has completed). Alternatively, the attacker has the ability to deny some availability, but the loss of availability presents a direct, serious consequence to the impacted component.

NIST

CREATED

4 months ago

CREATED

23 days ago

UPDATED

23 days ago

ADVISORY IDGO-2026-5506⁠

EXPLOITABILITY SCORE

EXPLOITS FOUND

COMMON WEAKNESS ENUMERATION (CWE)-

RATING UNAVAILABLE FROM ADVISORY

Chainguard

CREATED

20 hours ago

UPDATED

20 hours ago

ADVISORY ID

CGA-82cw-rccf-76r2

EXPLOITABILITY SCORE

EXPLOITS FOUND

COMMON WEAKNESS ENUMERATION (CWE)-

RATING UNAVAILABLE FROM ADVISORY

Photon

CREATED

CREATED

4 months ago

UPDATED

4 months ago

ADVISORY ID

MINI-xxr2-2j66-xw53

EXPLOITABILITY SCORE

EXPLOITS FOUND

COMMON WEAKNESS ENUMERATION (CWE)-

RATING UNAVAILABLE FROM ADVISORY

CVE-2026-29181

Summary

severity

relevant links

vulnerability details

root cause

impact

proof of concept

fix recommendation

Common Weakness Enumeration (CWE)

CWE-770⁠

CWE-400⁠

CWE-770⁠

Advisories

GitHub

CVSS SCORE

Attack Vector (AV)Network

Attack Complexity (AC)Low

Privileges Required (PR)None

User Interaction (UI)None

Scope (S)Unchanged

Confidentiality (C)None

Integrity (I)None

Availability (A)High

NIST

CVSS SCORE

Debian

CVSS SCORE

Ubuntu

CVSS SCORE

GoLang

Chainguard

Photon

CVSS SCORE

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